Proceedings of the 16th International Symposium on Automotive Lighting Technical University Darmstadt Laboratory of Adaptive Lighting Systems and Visual Processing Published by Prof. Dr.-Ing. Habil. Tran Quoc Khanh Tran Quoc Khanh (Hrsg.) Laboratory of Adaptive Lighting Systems and Visual Processing Technical University Darmstadt Darmstadt, Germany https://doi.org/10.26083/tuprints-00030825 © The Editor(s) (if applicable) and The Author(s) 2025. This book is an open access publication. Open Access This book is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. 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Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 16th International Symposium on Automotive Lighting Steering Board Dr. C. Amsel, ZKW Group GmbH, AT S. Berlitz, AUDI AG, GER Dr. J. Bullough, Icahn School of Medicine, USA Dr. A. Freiding, Hyundai Motor Europe Technical Center, GER Dr. W. Huhn, GTB President & DVN Senior Advisor, GER Prof. T. Q. Khanh, TU Darmstadt, GER Dr. M. Kleinkes, Forvia HELLA, GER M. Komatsu, Koito Manufacturing Co. Ltd, JPN R. Krautscheid, Federal Ministry for Digital and Transport, GER Dr. M. Maier, Mercedes Benz AG, GER K. Matauschek, Valeo, FRA P.-H. Matha, SIA Vision President and DVN CEO, SWE Dr. phil. nat. R. Neumann, GTB, GER Dr. E.-O. Rosenhahn, Marelli Automotive Lighting Reutlingen GmbH, GER P. Röckl, Stellantis N.V., GER D. Vanderhaeghen, Lumileds, GER Foreword It is a pleasure to present the Proceedings of the 16th International Symposium on Automotive Lighting (ISAL), taking place in Darmstadt, Germany, from 22–24 September 2025. Since the first PAL conference in 1995, ISAL has grown into a leading international forum for forward-looking developments in automotive lighting. Over the years, its scope has expanded significantly, now encompassing related fields such as communication systems, sensor integration, and artificial intelligence. The 2025 edition reflects this evolution. Contributions from around 200 authors from industry, academia, research institutes, and regulatory bodies offer deep insight into current research, trends, and future directions in the field. This year’s symposium places particular emphasis on several key areas: the ongoing advancement of high-resolution headlamps and their integration into modern lighting functions, the increasing importance of Car2X communication and adaptive signaling made possible by modern projection technology, and the integration of camera-based lighting into advanced driver assistance systems (ADAS). Another important focus is glare and visual performance, optimizing visibility and minimizing discomfort in night-time driving. Finally, sustainability has emerged as a critical factor in the full lifecycle of lighting systems, from design through to disposal. A significant milestone in 2025 is that all accepted papers and the complete proceedings will be published as open access for the first time in ISAL's history. This will make the research freely accessible to you and the global community. We wish you a productive and inspiring ISAL 2025 in Darmstadt. May these proceedings support your ongoing research and innovation. We look forward to welcoming you again at ISAL 2027. Yours sincerely, Prof. Dr.-Ing. habil. Tran Quoc Khanh i ISAL 2025 – Proceedings Contents I. ADAPTIVE SIGNALING 1 THE EVOLUTION OF SURFACE LIGHT GUIDES IN AUTOMOTIVE SIGNAL-LIGHTING 2 B. Kreipe1, C. Studeny1 1: Volkswagen, Germany AN EFFICIENT PROJECTOR CONCEPT TO MEET THE CHALLENGE OF SIGNAL ROAD PROJECTION AT DAYTIME 12 T. Hornung1 1: odelo GmbH, Hedelfinger Straße 137, 70329 Stuttgart, Germany ADS MARKER LAMPS – RESULTS OF FIELD TESTING AND CUSTOMER STUDIES 22 Daniel Betz1, Alexander Bohn1, Stephan Muecke1, Stephanie Seupke1, Nikolas Sciortino2 1: Mercedes-Benz AG, 71059 Sindelfingen, Germany 2: Mercedes-Benz R&D North America, Inc., Farmington Hills, Michigan 48331, USA II. ADAS AND LIGHTING FOR ADAS 34 POTENTIAL ENERGY SAVINGS OF ADAPTIVE DRIVING BEAM HEADLAMPS USING ADAS SENSORS BY ENVIRONMENTAL AWARE LIGHTING CONTROL 35 Yunji Heo1, Hyeran Kang2, Chan-Su Lee2, Jaebeom Lee1, Gilwon Han1 1: Hyundai Mobis, 17-2 Mabuk-ro 240beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 2: Yeungnam University, 280, Daehak-ro, Gyeongsan-si, Gyeongsangbuk-do EFFECTS OF LUMINOUS INTENSITY AND MODULATION ON NIGHTTIME PERCEPTION OF AUTOMATED DRIVING SYSTEM MARKER LAMPS 45 A. Abe1, Y. Kato1, M. Sekine1, Y. Aoki1 1: National Traffic Safety and Environment Laboratory, 42-27, Jindaiji- Higashimachi 7-chome, Chofu, Tokyo, 182-0012, Japan CONTRAST OPTIMIZATION FOR CAMERA-BASED ADAS TO ENHANCE OBJECT VISIBILITY USING PIXEL LIGHT TECHNOLOGY 56 J. Lerch1, T. Q. Khanh1, M. Hofmann2, A. Guenther2, S. Grötsch2 1: TU Darmstadt, Laboratory of Adaptive Lighting Systems and Visual Processing, Darmstadt, Germany ii ISAL 2025 – Proceedings 2: ams OSRAM Group, Regensburg, Germany DIRECT IMAGING HEADLIGHTING SOLUTIONS – A COMPARISON OF LED ARRAY-BASED SOLUTIONS 67 J. Schug1, R. Bertram1, X. Denis2, M. Schakel2 1: Nichia Automotive Innovation Center GmbH, Germany 2: Nichia Europe GmbH, Germany SMART HEADLIGHTS WITH COAXIAL INTEGRATION OF LIDAR AND RADAR SENSING 77 D. Stefanidi1*, P. Schreiber1, S. Vogel2, K. Täschner3, K. Albert4, M. Schepers5, A. Gillner2 1: Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Straße 7, 07745 Jena, Germany 2: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, 52074 Aachen, Germany 3: Fraunhofer Institute for Electron Beam and Plasma Technology FEP, Winterbergstraße 28, 01277 Dresden, Germany 4: Fraunhofer Institute for Microelectronic Circuits and Systems IMS, Finkenstraße 61, 47057 Duisburg, Germany 5: Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR, Fraunhoferstraße 20, 53343 Wachtberg, Germany HIGH-FREQUENCY LED-HEADLIGHT FOR FASTER PSEUDO IMAGE GENERATION AND OBJECT 87 L.Hänsel1, T. Bertram2 1: L-LAB, Germany 2: University Dortmund, Germany IMPACT OF VEHICLE HEADLIGHT DISTRIBUTION AND STREET LIGHTING ON CAMERA SIGNAL QUALITY IN NIGHTTIME AUTONOMOUS DRIVING: A FIELD STUDY 99 D. Hoffmann1 1: TU Darmstadt – FG ALSVV, Germany III. ADVANCED LIGHTING SYSTEMS 100 ALL PHOTONS ARE NOT CREATED EQUAL: OPTIMIZING INTELLIGENT HEADLIGHTS UNDER ADAPTIVE STREETLIGHTING SYSTEMS 101 J. D. Bullough1 1: Light and Health Research Center, Icahn School of Medicine at Mount Sinai, 150 Broadway, Suite 560, Albany, NY 12180 USA ISAL 2025 – Proceedings iii DIVERSITY OF HEADLAMP AUTO-LEVELING SW FUNCTIONS ACCORDING TO IMU SENSOR PERFORMANCE 109 Sanghwan Seo1, Jaebeom Lee1, Myeongje Kim1, Gilwon Han1 1: Hyundai Mobis, Seoul Korea ADAPTIVE HEADLAMP DESIGN FOR TWO-WHEELERS: ENHANCING NIGHTTIME VISIBILITY AND SAFETY 124 Shanmukha Pradeep K1, Ganapathy Subramanian S1 1: TVS Motor Company, Post Box no 4, Harita, Hosur-635109, India. APPLICATION OF KÖHLER ILLUMINATION IN REAR LAMP FOG DESIGN 137 M. Svettini1, G. Macorini1 1: Marelli, Tolmezzo Italy IV. AI AND MACHINE LEARNING IN AUTOMOTIVE LIGHTING 147 COMPREDICT’S AUTOMATIC VIRTUAL HEADLIGHT LEVELING SENSOR – REPLACING HARDWARE SENSORS BY A PRECISE AND FULLY COMPLIANT SOLUTION 148 G. Desnouvaux1, A.D. Bahrouni1, V. Vijayan1, M. Zeller1 1: COMPREDICT GmbH, Germany EDAG GROUP - EDLIGHT & HOMOGENIUM 162 Jannes Buthmann1, Julian Metzger1, Tibor Giesen1 1: EDAG Group AI-ASSISTED ACCELERATED AND MODULARITY-FOCUSED PRE-DEVELOPMENT OF MODULE LAMPS 167 S. Gane1, S. Daulatabad1, R. Purandare1 1: Mercedes-Benz R&D India Pvt Ltd, ETZ SEZ, Hinjewadi Phase 2, Pune-411057, India SEMANTIC SEGMENTATION OF CONDENSATION IN AUTOMOTIVE HEADLIGHTS USING DEEP LEARNING 176 S. Wichmann1, K. Sedlbauer2, R.Göttig2, C. Bremer1, S. Ecker1 1: BMW Group, Petuelring 130, 80809 München 2: Technische Universität München, Arcisstraße 21, 80333 München V. CAR INTERIOR AND AMBIENT LIGHTING 183 DESIGNING A LIGHT-BASED EXTENSION OF THE VEHICLE ENVIRONMENT FOR MOTION SICKNESS MITIGATION 184 L. Rottmann1, A. Stang1, A. Johannsen1, M. Niedling2 iv ISAL 2025 – Proceedings 1: L-LAB, 2: HELLA GmbH & Co. KGaA, Rixbecker Straße 75 59552 Lippstadt BIOPHILIA MEETS IMMERSIVE INTERIOR LIGHTING: HOW LIGHT ART TRANSFORMS CARS INTO AN EMOTIONAL SPACES. 194 L. Nguyen1 1: feno GmbH, Raiffeisenallee 3, 82041 Oberhaching, Germany HIGH-RESOLUTION REFLECTION MEASUREMENTS MADE EASY, USING THE EXAMPLE OF VEHICLE DISPLAYS 201 I. Rotscholl, A. Voelz, K. Kirchhoff, C. Schwanengel, U. Krueger1 1: TechnoTeam Bildverarbeitung GmbH, Werner-von-Siemens Str. 5, 98693, Ilmenau, Germany VISIBILITY OF INTERIOR PROJECTIONS: EFFECTS OF SURFACE CHARACTERISTICS 212 Dr. Alexander Stuckert1 1: BMW Group, Knorrstr. 148, 80788 Munich, Germany ADVANCED LIGHT SIGNATURE AS COMMUNICATION DEVICE 222 J. Le1 1: STELLANTIS, Bahnhofsplatz, 65423 Rüsselsheim am Main, Germany VI. CAR2X COMMUNICATION 223 HOW PEDESTRIANS LIKE AUTOMATED VEHICLES TO COMMUNICATE VIA LIGHT-BASED EHMIS 224 A. Johannsen1, A. Waldmann1, L. Rottmann1, M. Kaup2 1: L-LAB, Rixbecker Straße 75, 59552 Lippstadt, Germany 2: FORVIA HELLA, Rixbecker Straße 75, 59552 Lippstadt, Germany EFFECT OF EXTERNAL HMIS ON PEDESTRIAN SAFETY AND TRAFFIC FLOW – A MOTION CAPTURE STUDY 234 F. Maier1, R. Leute1, M. Paulokat1, E.-O Rosenhahn1 M. Brunner2, M. Rehmann2, C. Curio2 1: Marelli Germany GmbH, Germany 2: Reutlingen University of Applied Science, Germany THE DISPLAY FORMULA 247 D. Duhme1 1: HELLA GmbH & Co. KGaA Rixbecker Straße 75 59552 Lippstadt, Germany LIGHT-BASED COMMUNICATION WITH OTHER ROAD USERS - AN OVERVIEW 257 M. Baumann1 1: Karlsruhe Institute of Technology, Karlsruhe ISAL 2025 – Proceedings v INTUITIVE COMMUNICATION BETWEEN AUTOMATED VEHICLES AND VULNERABLE ROAD USERS: AN EXPERIMENTAL STUDY USING VIRTUAL REALITY 258 Ru Li1,2, Derrick G. Watson2, Yan Liang1, Tran Quoc Khanh3, Jonas Bix3, Valery Ann Jacobs1 1: ETEC Department & MOBI research center, Vrije Universiteit Brussel, Brussels, Belgium 2: Department of Psychology, University of Warwick, Coventry, UK 3: Laboratory of Adaptive Lighting Systems and Visual Processing, Department of Electrical Engineering and Information Technology, Technical University of Darmstadt, Darmstadt, Germany ON-VEHICLE DISPLAYS AND ON-GROUND PROJECTION FOR AUTOMATED VEHICLE COMMUNICATION - TEST TRACK STUDY RESULTS 268 O. Puscasu1, A. Sahaï2, N. Métayer2 1: VALEO Light, 34 rue Saint-André, 93000 Bobigny, France 2: VEDECOM Institute, 23 bis allée des Marronniers, 78000 Versailles, France VII. DIGITAL LIGHTING AND PROJECTION SYSTEMS 280 DYNAMIC GROUND PROJECTION: TRENDS, PERFORMANCE, DIMENSIONS, SAFETY ASPECTS 281 F. Freytag1, S. Schildmann1, E.-O. Rosenhahn1 1: Marelli Germany GmbH, Ludwig-Erhard-Straße 4, 72760 Reutlingen POLARIZATION MULTIPLEXED META-OPTIC SYMBOL PROJECTION FOR EHMI 289 L. Hiller1, M. Niedling1 1: HELLA GmbH & Co. KGaA, Rixbecker Straße 75, 59552 Lippstadt, Germany MICRO-SEGMENTED LED DIE TECHNOLOGY FOR DYNAMIC SURROUND CAR ILLUMINATION 301 B. Spinger1,N. Lesch1, A. Timming1, A. van der Sijde2, N. Pfeffer2, R. Engelen2, W. Soer2 1: Lumileds Aachen GmbH, Philipsstrasse 8, D-52068 Aachen, Germany 2: Lumileds Netherlands B.V., Beemdstraat 42-46, 5652 AB Eindhoven, Netherlands DIGITAL SOLUTIONS AND NEW FUNCTIONALITIES - INNOVATIONS IN FRONT LIGHTING 310 Gerald Boehm1 1: ZKW, Austria, Rottenhauser Straße 8, 3250 Wieselburg vi ISAL 2025 – Proceedings ENHANCING RESOLUTION IN MICRO-LED PIXEL HEADLAMP PROJECTORS VIA MECHANICAL WOBULATION: A FEASIBILITY STUDY 319 ChangHi Lee1,2, and Jae-Hyeung Park3 * 1: Graduate School of Engineering Practice, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea 2: Hyundai Mobis, Korea, 203, Teheran-ro, Gangnam-gu, Seoul, Republic of Korea 3: Department of Electrical and Computer Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea VIII. GLARE 328 NEW STATISTICS AND MEASUREMENTS ABOUT GLARE CAUSED BY HEADLAMPS 329 E.-O. Rosenhahn, S. Spatzek1 1: Marelli Germany GmbH, Ludwig-Erhard-Str. 4, 72760 Reutlingen, Germany GLARE CONTRIBUTORS - A METASTUDY ON SCIENTIFIC RESEARCH ABOUT DIFFERENT ASPECTS OF GLARE 340 Michael Hamm1 1: TU Darmstadt - Laboratory of Adaptive Lighting Systems and Visual Processing DISCOMFORT GLARE FROM LED LIGHTING: IMPACT OF THE SIZE OF THE GLARE LIGHT SOURCE AND THE BACKGROUND LUMINANCE 351 E. Kemmler1, M. Peier1, Dr. A. Walkling2, Prof. T.Q. Khanh1 1: Technical University of Darmstadt, Hochschulstraße 4a, 64289 Darmstadt 2: Federal Highway and Transport Research Institute, Brüderstraße 53, 51427 Bergisch Gladbach GLARE CAUSES IN NIGHTTIME TRAFFIC - HOW CAN WE MINIMIZE THE RISK OF GLARING HEADLIGHTS TO INCREASE TRAFFIC SAFETY? 360 A. Erkan1, A. Hainzlmaier1, S. Berlitz1 1: Audi AG, Germany ADAC SYMPOSIUM GLARE IN ROAD TRAFFIC 369 Burkhard Böttcher1 1: ADAC e. V., Hansastr. 19, 80686 München FIELD STUDY ON DISCOMFORT GLARE FROM HEADLAMPS WITH SMALL LIGHT-EMITTING AREAS 374 M. Niedling1, J. Locher1, A. Johannsen1 ISAL 2025 – Proceedings vii 1: L-LAB, Rixbecker Straße 75, 59552 Lippstadt, Germany EYETRACKING OF XR-HEADSETS AND ITS POTENTIAL TO ACCESS GLARE VIRTUALLY 384 M. Robra1, H. Hoppen1, F. Tietzsch1, B. Lamontain1 1: Hochschule Magdeburg-Stendal, Magdeburg IX. HEADLAMP SYSTEM DESIGN 394 LIGHTING SOFTWARE DESIGN FOR SOFTWARE DEFINE VEHICLE 395 B. Huvet, A. Lubat, R. Belloc, F. Nigon 1: VALEO, 34 rue Saint André - 93012 - Bobigny - FRANCE DEVELOPMENT OF A DUAL INJECTION SILICONE-BASED SEAMLESS AUTOMOTIVE LAMP FOR EURO NCAP SAFETY 404 Eun-Bi Kwon1, Seok-Ho Jeong1, Jung-Young Kim1 1: HYUNDAI MOBIS, Gyeonggi-do, 16891, Republic of Korea VERTICAL DESIGNS FOR RID SOLUTIONS: CHALLENGES FOR LEGAL REQUIREMENTS AND CONSUMER RATINGS 410 V. Pramhaas1, D. Go1 1: ZKW, Rottenhauser Str. 8, 3259 Wieselburg, Austria ELECTROCHROMIC SYSTEMS FOR ADAPTIVE AUTOMOTIVE LIGHTING 419 S. Tomko1, M. Schott2 1: FORVIA - HELLA AUTOTECHNIK NOVA, s.r.o., Mohelnice, Czech Republic 2: Fraunhofer Institute for Silicate Research ISC, Würzburg, Germany MARELLI'S SOLUTION: LIGHTING WITHIN ZONAL-ARCHITECTURES 426 Wolfgang Ritter1 1: Marelli Germany GmbH, Ludwig-Ehrhard-Straße 4, 72760 Reutlingen FLATLIGHT-TECHNOLOGY – FORVIA HELLAS AND REICHLES EXPERTISE FOR INDIVIDUAL STYLINGS & DIFFERENTIATIONS WITH FEMTO LASERED MICROOPTICS 438 Martin Mügge1, Marco Reichle2, 1: FORVIA HELLA, Rixbecker Str. 75, 59552 Lippstadt, Germany 2: REICHLE Technologiezentrum GmbH, Alte Weberei 6-8, 73266 Bissingen/Teck, Germany X. HIGH DEFINITION HEADLAMPS 448 CHALLENGES OF HD-PIXELATED PROJECTION MODULES IN HEADLAMPS WITH INCREASING DEMANDS ON RESOLUTION 449 Andreas Bieler1, Reza Larimian1 1: ZKW, Rottenhauser Str. 8, 3250 Wieselburg, Austria viii ISAL 2025 – Proceedings HOW TO WIN ALL LIGHTING TROPHIES WORLDWIDE: DIGITAL LIGHTING ON A SINGLE LAMP HARDWARE 459 M. Heidrich, S. Spatzek, K. F. Albrecht, T. Wagner Marelli Germany GmbH, Ludwig-Erhard-Str. 4, 72760 Reutlingen, Germany ETHERNET-BASED SOFTWARE-LESS HEADLAMP ARCHITECTURE FOR NEXT-GENERATION AUTOMOTIVE LIGHTING 470 Jiyoung Jeong1, Sungdu Kwon1, Woongbae Yoon1, Namyong Park1, Byungwoo Jeoung1 1: LG Electronics, 10 Magok jungang 10-ro, 07796, Seoul, Republic of Korea OPTIMIZATION OF ADB SYSTEMS FOR PERCEPTIBILITY WHEN USING HIGH RESOLUTION LIGHT SOURCE MODULES 481 Sinan Yargeldi1, Stephan Finn1 1: Mercedes-Benz AG, Stuttgart, Germany INTEGRATION STUDY OF VEHICLE POSTURE SENSORS FOR DYNAMIC CONTROL OF HD LIGHTING 492 Hyun-Chang Hwang1, Jung-sub Lim 2, Sang-Hwan Seo 3, Jae-beom Lee 4, Gil-won Han 5 1-5: Hyundai Mobis, Hyundai Mobis, 17-12, Mabuk-ro 240beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do, Republic of Korea 3D VIRTUAL REALITY TESTING-TOOL FOR GFHB-ALGORITHM 500 A. Kneib1, S. Ramanan1, S. Poppe1 1: Stellantis N.V. / Opel Automobile GmbH, Bahnhofsplatz, 65423 Rüsselsheim COMPARISON OF DIFFERENT ADAPTIVE LIGHT DISTRIBUTIONS FOR AUTOMATED DRIVING 510 N. Müller1, M. Waldner1, T. Bertram1 1: TU Dortmund University, Institute of Control Theory and Systems Engineering (RST), Dortmund, Germany ZONE-BASED MATRIX HEADLIGHT FEEDBACK CONTROL 521 M. Waldner1*, N. Müller1*, T. Bertram1 1: TU Dortmund University, Institute of Control Theory and Systems Engineering (RST), Dortmund, Germany ENERGY-EFFICIENT PEDESTRIAN MARKER LIGHT BASED ON POSE-PROBABILITY FOR COMPUTER VISION 532 F. Glatzel1, N. Müller1, M. Waldner1, T. Bertram1 ISAL 2025 – Proceedings ix 1: TU Dortmund University, Institute of Control Theory and Systems Engineering (RST), Dortmund, Germany XI. LIGHTSOURCES AND OPTICAL INNOVATIONS 544 INTEGRATED AREA-LIGHT SOURCES IN RCL PAVE THE WAY FOR NEW AUTOMOTIVE SIGNAL LIGHTING APPLICATIONS. 545 Erwin Lang1, Stefan Ludwig1, Manuel Walch1, Daniel Kraus1, Michael Jobst1, Alexander Günther1, Matthias Popp2, Christoph Stuhlinger2 1: ams OSRAM Group, 2: LEONHARD KURZ Stiftung & Co. KG, Germany SMART PIXEL CONFIGURATIONS FOR MOST EFFICIENT FULL HEADIGHTING MATRIX BEAM APPLICATIONS 557 T. Anger1 1: Lumileds Aachen GmbH, Philipsstrasse 8, 52068 Aachen, GERMANY INVESTIGATION OF A NEW BI-LED FRONT LIGHTING CONCEPT MODULE FOR A-B SEGMENT AND LCV VEHICLES AND ITS INTEGRATION INTO STELLANTIS’ ELECTRICAL/ELECTRONIC ARCHITECTURE 558 N. Costa1, F. Garibaldi2 Stellantis Europe S.p.A., Italy ULTRA-EFFICIENT AND HIGHLY SAFE DLED LIGHTING TECHNOLOGY FOR AUTOMOTIVE APPLICATIONS 567 Seok-Ho Jeong1, Eun-Bi Kwon1,Brandon Bang2, Seong-geun Song3 1: Hyundai Mobis, 17-2 Mabuk-ro 240beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 16891, Republic of Korea 2: AMS OSRAM, 39th Floor, FKI Tower, 24 Yeoui-daero, Yeongdeungpo-gu, Seoul 07320, Republic of Korea 3: IL Science, 7F, Units 702–710, 25 Beobwon-ro 11-gil, Songpa-gu, Seoul, Republic of Korea HIGH-EFFICIENCY ADB HEADLAMP MODULE BASED ON MLA TECHNOLOGY 575 Michael Scheuerer1, Stefan Hildebrand1, Sergey Khrushchev1, Dr. Christoph Gärditz1, Dr. Olga Fryckova2, Vladimir Gründling2 1: OPmobility, Im Gewerbepark C25, 93059 Regensburg, Germany 2: Focuslight Switzerland, Rouges-Terres 61, 2068 Hauterive, Switzerland ATHERMALIZATION OF GLASS AND PLASTIC HYBRID LENS WITH LARGE APERTURE 584 Dr. Cheng Jiang1,2, Dr. Jun She2, Prof. Muqing Liu1 1: Fudan University, Shanghai, China x ISAL 2025 – Proceedings 2: Yejia Optical Technology Corporation, Dongguan, Guangdong, China XII. SUSTAINABILITY & SYSTEM APPROACH 594 SERVICE-ORIENTED ARCHITECTURES ENABLING FUTURE VEHICLE LIGHTING 595 F. Muttenthaler1, M. Artmann2 1: ZKW Lichtsysteme GmbH, Samuel-Morse-Straße 18 2700 Wiener Neustadt Austria 2: ZKW Group GmbH, Rottenhauser Straße 8 3250 Wieselburg Austria AUTOMATIC DYNAMIC HEADLAMP LEVELING UTILIZING CAMERA-BASED VEHICLE PITCH DETECTION 605 L. Lottner1, M. Reiter1, B. Herrmann1 1: Ford-Werke GmbH, Henry-Ford-Straße 1 50735 Köln TEMPERATURE BEHAVIOR OF DIFFERENT LIGHT FUNCTIONS: AN ANALYSIS BETWEEN BATTERY ELECTRIC VEHICLES AND INTERNAL COMBUSTION ENGINE VEHICLES 615 T. Schlürscheid1,2, F. Blanc1, T. Khanh2 1: BMW AG, Knorrstraße 147, 80807 Munich 2: TU Darmstadt – Fachgebiet Adaptive Lichttechnische Systeme und Visuelle Verarbeitung, Hochschulstraße 4a, 64289 Darmstadt BUILDING BLOCKS FOR THE SOFTWARE-DEFINED VEHICLE 625 B. Kreipe1, J. Speh 1 1: Volkswagen, Germany MEETING PREMIUM AUTOMOTIVE LIGHTING REQUIREMENTS WITH CIRCULAR POLYMERS: RECYCLING CHALLENGES AND MATERIAL SOLUTIONS IN THE NALYSES PROJECT 635 K. Pupovac1, M. Roppel1, J. Helmig1 1: Covestro Deutschland AG, Kaiser-Wilhelm-Allee 60, 51373 Leverkusen USE OF RECYCLED-BASED LIGHT GUIDES AND THEIR IMPACT ON THE CO₂ FOOTPRINT OF AMBIENT LIGHTING SYSTEMS 645 Bjarne Grunenberg1, Melanie Helmer1, Svenja Wepfer1, Klemens Peschat2, Roland Lachmayer3 1: Mercedes-Benz Group Aktiengesellschaft, Stuttgart 2: Hochschule der Medien, Stuttgart 3: Leibniz Universität Hannover, Hannover JUST IN LIGHT: AN ENERGY-EFFICIENT APPROACH TO AUTOMOTIVE LIGHTING 656 H. El Idrissi1, M. Ait-Messaoud1, A. de Lamberterie1, Yin Guo1 ISAL 2025 – Proceedings xi 1: VALEO Light, 34 rue Saint-André, 93000 Bobigny, France POTENTIAL ANALYSIS OF CAR HEADLIGHT REPAIR THROUGH LENS REPLACEMENT AND ITS IMPLICATIONS FOR THE CO2E FOOTPRINT 667 Michael Muttenthaler1, Eva Schneck1 1: ZKW Group GmbH, Austria EVALUATION OF THE NECESSARY INTENSITY OF DAYTIME RUNNING LIGHTS AT DIFFERENT AMBIENT ILLUMINANCE LEVELS 677 Markus Alexander Peier1, Tran Quoc Khanh1 1: Technische Universität Darmstadt, Fachgebiet Adaptive Lichttechnische Systeme und Visuelle Verarbeitung, Hochschulstraße 4a, 64289 Darmstadt SUSTAINABILITY EVALUATION OF REPAIR AND REMANUFACTURE SOLUTIONS IN A CIRCULAR HEADLAMP ECONOMY* 684 C. Spork1, M. Niedling2, J. Meyer3, A. Trächtler4 1: L-LAB, Germany 2: HELLA GmbH Co. KGaA, Germany 3: University of Applied Science Hamm-Lippstadt, Germany 4: University of Paderborn, Germany DEVELOPMENT OF A HARDWARE-INDEPENDENT ADAPTIVE LIGHTING SOFTWARE PLATFORM FOR INTELLIGENT HEADLAMP SYSTEMS IN SOFTWARE-DEFINED VEHICLES 695 Dongman.J, Jiyeong.J, Kyusang,Y, Hyunjae.J, Byungwoo.J LG Electronics, Seoul, Republic of Korea CIRCULAR ECONOMY APPROACHES IN AUTOMOTIVE LIGHTING – INSIGHTS FROM THE NALYSES PROJECT 705 C. Schmidt1, M. Niedling1 J. Helmig2, S. Forbes3, J. Jardin4, S.Stieren5,,N.Fitkau6,,H.Peitzmeier7 1: FORVIA HELLA, 59552 Lippstadt 2: Covestro Deutschland AG, 51373 Leverkusen 3: Geba, 59320 Eningerloh 4: University of Applied Science Hamm-Lippstadt, 59063 Hamm 5: Fraunhofer IEM, 33102 Paderborn 6: HNI, University of Paderborn, 33098 Paderborn 7: E-LAB, 59552 Lippstadt 1ST APPROACH TO REDUCE CARBON FOOTPRINT IMPACT OF LIGHTING PARTS 716 F. Bedu1, V. Calais1 xii ISAL 2025 – Proceedings 1: RENAULT Group, Technocentre – 1 avenue du Golf – 78280 Guyancourt - FRANCE REGULATORY-COMPLIANT ENERGY-SAVING POTENTIAL FOR THE PASSING BEAM OF MATRIX LED HEADLAMPS 724 N. Fittkau1, L. Bußemas1, K. Malena1, S. Gausemeier1, A. Trächtler1,2 1: Chair of Control Engineering and Mechatronics, Heinz Nixdorf Institute, Paderborn University, Fürstenallee 11, 33102 Paderborn, Germany 2: Fraunhofer Institute for Mechatronics Systems Design IEM, Zukunftsmeile 1, 33102 Paderborn, Germany XIII. VISUAL PERFORMANCE 735 PSYCHOPHYSICAL TESTING OF SAFETY ASPECTS FOR DAYTIME RUNNING LAMPS 736 Yan Liang1, Abdeslam Bayhi1, Nils Mens1, Naoufal Bouchaara1, Arjen Mentens1, Guillaume Dotreppe1, Dylan Michaël V Vandamme1, Ru Li1, Valéry Ann JACOBS1 1: Merlin at MOBI research center, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium ASSESSING THE CORRELATION BETWEEN HEADLIGHT SAFETY PERFORMANCE RATING (HSPR) AND THE VISIBILITY LEVEL FOR VARYING OBJECT REFLECTION COEFFICIENTS 745 N. Kreß1, K. Kunst1, T.Q. Khanh1 1: Technical University Darmstadt, Laboratory of Adaptive Lighting Systems and Visual Processing, Germany PWM FREQUENCIES – FEASIBILITY TO AVOID THEIR NEGATIVE EFFECTS 757 I. Cadenas1 1: Renault Group - Ampere ST, France EFFECT OF REAR LAMP SHAPE AND PWM FREQUENCY ON THE VISIBILITY OF THE PHANTOM ARRAY EFFECT 774 Hyeran Kang1, Shinwon Park2, Chan-Su Lee1 1: Yeungnam University, 280, Daehak-ro, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea. 2: SL corporation, 77, Gongdan 6-ro, Jillyang-eup, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea. A FUNCTIONAL NEUROIMAGING STUDY OF NIGHTTIME PEDESTRIAN VISIBILITY IN AUTOMOBILE DRIVERS. 779 ISAL 2025 – Proceedings xiii S. Oyama1, H. Fujii1, Y. Nagashima2, Y. Shirota3, A. Kasahara4, M. Ueda5, M. Komatsu1 1: KOITO MANUFACTURING CO.,LTD., Japan 2: Biomedical Photonics Laboratory, Division of Translational Biomedical Photonics, Institute of Photonics Medicine, Hamamatsu University School of Medicine, Japan 3: Department of Clinical Laboratory, the University of Tokyo Hospital, Japan 4: Radiology Center, The University of Tokyo Hospital, Japan 5: Department of Neurology, Graduate School of Medicine, the University of Tokyo, Japan A COMPUTATIONAL FEEDBACK MODEL FOR GENERALIZED HOMOGENEITY EVALUATIONS OF LUMINANCE DISTRIBUTIONS 790 K.Schier1, M. Niedling2, C. Schmidt1 1: L-LAB, Rixbeckerstr. 75, 59552 Lippstadt, Germany 2: FORVIA HELLA, Rixbeckerstr. 75, 59552 Lippstadt, Germany DETECTABILITY OF NONUNIFORMITIES IN AUTOMOTIVE EXTERIOR DISPLAYS: A STUDY FOR MODEL VALIDATION 804 Lars Wagner1, Katrin Schier1, Mathias Niedling1, Meike Barfuß2 1: L-LAB, Germany 2: Fachhochschule Südwestfalen, Germany HEADLAMP PERFORMANCE RATINGS: A COMPARATIVE ANALYSIS OF HSPR AND VLPS 815 K. Kunst1*, D. Hoffmann1, Nikolai Kreß1, Dr. M. Hamm1, Prof. Dr. T.Q. Khanh1, 1: Laboratory of Adaptive Lighting Systems and Visual Processing, TU Darmstadt, Darmstadt, Germany NEW METHODOLOGY FOR HOMOGENEITY EVALUATION FROM QUALITATIVE TO QUANTITATIVE 832 CALAIS Valère1, BEDU François1, BENAMIRA Barbara1 1: Renault Group, France 1 ISAL 2025 – Proceedings Adaptive Signaling I. Adaptive Signaling 16. International Symposium on Automotive Lighting Darmstadt, 22. – 24. September 2025 Article DOI: 10.26083/tuprints-00030850 DOI (proceedings): 10.26083/tuprints-00030825 ISAL 2025 – Proceedings 2 This article is licensed under CC BY 4.0. https://creativecommons.org/licenses/by/4.0/ Adaptive Signaling The evolution of surface light guides in automotive signal-lighting B. Kreipe1, C. Studeny1 1: Volkswagen, Germany 1. Abstract Surface light guides based on edge-light materials provide a cost-effective solution for achieving homogeneous OLED-like lighting. These elements can be used as freestanding or staggered design components and are widely implemented in both framed (e.g. VW ID.4, ID.Unyx, T-Cross PA, Arteon, Passat, Tayron, etc.) and frameless vehicle designs (e.g. SEAT/Cupra Tavascan, Formentor). As lamp sizes decrease, packaging constraints become more challenging, creating a need for function integration, such as bifunctional designs. Consequently, high-luminance functions like turn signals and brake lights must also be realised within surface light guide technology. This paper presents two approaches to achieving high luminance in surface light guides. The first solution integrates micro-optics and a white reflector to enable bi-colour tail and turn signal functionality. We discuss challenges related to colour saturation in clear outer lenses, mitigation strategies, and series implementations. The second solution combines surface and classic light guides to enhance luminance through an edge-boost effect, demonstrated via in-house prototypes and series applications. Finally, we provide an outlook on future high-resolution applications, including segmented surface elements and hybrid systems incorporating micro-pixel LEDs. Keywords: Surface light guide, automotive signal lighting, homogeneity, bifunctional design, colour desaturation by ambient lighting, micro optics, edge boost 3 ISAL 2025 – Proceedings Adaptive Signaling 2. Introduction Modern taillights increasingly incorporate both functional and decorative illuminated elements, driving demand for advanced surface illumination technologies. For example, the Volkswagen Tiguan MY2021 features a strip-shaped illuminated area on the side of the taillight, serving a primarily aesthetic purpose (Fig. 1). Similarly, the Volvo S60 MY2014 integrates an illuminated surface between two linear light guides. Powered by the adjacent light pipes, this element serves as decorative lighting and represents an early example of surface light guide technology (Fig. 1). Figure 1: Early examples of surface illumination: Volvo S60 MY2014* with light curtain and VW Tiguan MY2021 with illuminated side area. The concept of surface light guides has long been employed for interior applications to achieve uniform illumination in instrument clusters and backlit displays (Fig. 2). Traditionally, these systems relied on multilayer diffuser foils. Early implementations for exterior lighting followed a similar approach [2], employing a stack of optical films on the front, a central light guide, a reflective layer at the back, and a surrounding frame (Fig. 3). While capable of delivering homogeneous illumination, such foil based concepts presented several drawbacks. Since no foil back moulding is possible, they require additional processing steps and precise alignment of multiple components, which imposes strict mechanical constraints and higher manufacturing costs. To adapt the principle of homogeneous surface illumination for exterior automotive lighting—and to enable greater styling flexibility—new optical concepts and materials were required. ISAL 2025 – Proceedings 4 Adaptive Signaling Figure 2: Scheme of a diffusion film based surface light guide (left) [1] and picture of a surface light guide of an instrument cluster backlight (right). Figure 3: Foil-based surface light guides: mock-up (left) and layer structure (right). Image taken from [2]. Since around 2017, organic light-emitting diode (OLED) technology has set new standards for surface illumination, offering exceptional homogeneity and enabling visually distinctive signature designs [3]. However, the high cost and limited scalability of OLEDs posed a challenge for broad implementation, especially in high-volume vehicle segments. A cost-effective alternative that could achieve a comparable visual effect using more readily available and scalable technologies such as LEDs had to be developed. This effort resulted in the introduction of a novel surface light guide concept in production vehicles such as the Volkswagen Arteon MY2020 and ID.4 MY2021 (Fig. 4). 3. First generation surface light guides Both the Arteon MY2020 and ID.4 MY2021 (Fig. 4) utilize surface light guides without any visible outcoupling structures. These surface light guides are edge-lit by LEDs, typically from at least one end face. For the first time, a specially developed plastic— referred to as LD12 light-diffusing material—was used as the light-guiding medium [4]. This material incorporates nanometre-sized scattering particles, enabling a highly uniform light distribution across extended distances. The designation "LD12" indicates 5 ISAL 2025 – Proceedings Adaptive Signaling its ability to maintain homogeneous illumination over a range of 12 cm when light is coupled from both ends [5]. To enhance optical performance, the surface light guides are enclosed by a frame and a white back wall. This design conceals illuminated edges and further increases perceived uniformity through a back-scattering effect (Fig. 5). Figure 4: Arteon and ID.4 tail lights with surface light guides. Figure 5: Exploded view of an ID.4 surface light guide element. Deep red LEDs provide a high quality light colour when lit on. The red appearance in the unlit (off) state is accomplished by incorporating red pigment directly into the light guide material. Since the light emitted from the surface light guide alone does not meet the required photometric values, additional optical elements such as classic light guides are added to the taillamp to ensure compliance with regulatory standards. A contrasting design approach is demonstrated by the Cupra brand, where surface light guides are implemented without frames or reflective back panels (Fig. 6). In these models, such as the Tavascan and Formentor, intentional overlay effects and glowing edges are used as design features. All in all, surface light guides have been used in a wide range of vehicle projects in both framed and frameless vehicle designs to date. ISAL 2025 – Proceedings 6 Adaptive Signaling Figure 6: Cupra Tavascan (left) and Formentor (right) taillights with frameless surface light guide designs. 4. Challenges of modern lamp designs A prevailing trend in automotive lighting design is the move toward smaller packaging. As available space continues to shrink, the integration of multiple lighting functions within a single element—such as combined tail/stop or tail/turn indicator lights—has become essential. While this approach addresses spatial constraints, it also introduces a number of complex challenges. High-intensity functions such as stop and turn signals demand either increased optical efficiency or a larger light-emitting surface, both of which must maintain a high degree of homogeneity. Additionally, combining heterochromatic light functions within a single element is only feasible using transparent light guides. In earlier designs, red outer lenses typically included dedicated transparent sections for non-red functions such as turn indicators. However, with the rise of large-area illuminated elements, the entire outer lens must now be transparent, regardless of the functions it supports. One of the major challenges with such large, exposed light-emitting surfaces arises from their interaction with ambient light—especially direct sunlight. Because modern transparent lens designs lack the colour-selective filtering properties of red-tinted outer lenses, all reflecting or scattering surfaces within the lamp now interact directly with the full spectrum and intensity of sunlight. This can significantly degrade both the daytime visibility and perceived colour saturation of the lighting function. Some examples for colour desaturation of tail functions are shown in Figure 7. The use of transparent or white filters and diffusors—including surface light guides with white reflectors—for coloured lighting functions (particularly red) results in colour desaturation. This occurs due to the superimposition of the LED’s emission spectrum and the intense ambient light spectrum reflected from the light-emitting surface. This effect is very pronounced in bright daylight and is demonstrated in Figure 8, which shows a simulated shift of the x,y chromaticity coordinates in the CIE colour diagram toward the white point. 7 ISAL 2025 – Proceedings Adaptive Signaling Despite these challenges, both optical as well as conceptual countermeasures can be taken to realise robust multifunctional surface light guide elements. Two of these approaches are discussed in the following chapter. Figure 7: Examples of colour desaturation for sun-exposed light elements: Directly exposed transparent volume elements* (left), white surface elements with micro-optics* (middle) and transparent volume elements* (right) behind transparent outer lens. Figure 8: Illustration of colour desaturation by ambient lighting. Comparison of night (upper) and day/twilight (lower) situation. ISAL 2025 – Proceedings 8 Adaptive Signaling 5. Next generation surface illumination To extend the applicability of surface light guide technology beyond taillight functions to additional signaling applications, a significant increase in light output is required. Furthermore, the integration of multiple functions within a single optical element allows for efficient usage of limited packaging space, while preserving high optical performance and enabling advanced design solutions. This requires tailored and consistent advancement of surface light guides adapted to the requirements for use in automotive signal lighting. The following section describes two successful technical approaches that have been implemented in production vehicles. 5.1 Micro optics and structuring The first approach leverages two key parameters to scale luminous flux: the light emitting area and optical efficiency. For this purpose, the surface light guides were enlarged and equipped with micro-optical structures to enhance light extraction. In order to integrate both the red tail light and the amber turn signal into a single illuminated surface, transparent PMMA in combination with a white background reflector is used (Fig. 9). The technical necessity of a completely colourless taillight incidentally marked the beginning of a brief paradigm shift in Volkswagen’s design language with the launch of the ID.7. Figure 9: ID.7 rear lamp signature. Figure 10 illustrates the structural layout of the ID.7 surface light guide concept. In contrast to first-generation designs, this configuration uses outcoupling optics on the rear side of the surface light guide. These optics are tailored to direct light within the angular range required for both position and turn signal functions, while maintaining a uniform illuminated appearance. The successful concept has since been adopted by several manufacturers [c.f. 6, 7]. The system is further enhanced by a front and rear frame, as well as a structured back reflector. The reflector incorporates light/dark contrast elements that help reduce colour 9 ISAL 2025 – Proceedings Adaptive Signaling desaturation under ambient lighting conditions (as discussed in Section 4) and contributes to additional visual homogenisation. Figure 10: Exploded view of the ID.7 surface light guide. 5.2 Edge-Boost concept The second approach is an evolution of the established LD12 concept (c.f. sec. 3). A homogeneous LD12 surface light guide is combined with an efficient transparent PMMA lightguide in one element. The LD12 element continues to serve as the tail light function, while the second light guide wraps around it, allowing light to be emitted laterally from its surface (Fig. 11, 12). An optional white separator is placed Figure 11: Golf 8 MY2024 rear lamp with tail signature and turn indicator. in between the two light guides to prevent crosstalk and enhance efficiency. The whole stack is housed in a black frame. This dual-guide setup offers multiple advantages. On the one hand, it boosts overall optical efficiency and enables the integration of additional functions, such as a stop light, within the same package. On the other hand, the transparent light guide allows the emission of different light colours from its edge—most PCB with LEDs Front frame Transparent surface light guide including micro-optics Rear frame and structured back wall ISAL 2025 – Proceedings 10 Adaptive Signaling notably amber—making it suitable for turn signal functionality. Despite this functional versatility, the distinct red appearance characteristic of rear lighting during the day is preserved through the red tinted LD12 element. Furthermore, the design is inherently immune to colour desaturation under ambient lighting conditions, since scattering surfaces are only made of red material and thus spectrally selective and transparent surfaces show a very low cross-section for backscattering of ambient lighting. Design wise, the elements can be used in the same manner as their monochromatic counterparts as freely positionable elements to create three-dimensional signatures (c.f. Fig. 4, 5 and 11). Figure 12: Exploded view of the Golf 8 edge-boost surface light guide. 6. Summary and Outlook For the first time, bi-functions for automotive signal lighting could be demonstrated in series using surface light guide technology. A combination of taillight and turn indicator was implemented by using different approaches. On the one hand, by scaling the surface area and efficiency using micro-optics. On the other hand, embedding surface light guides into a highly efficient light guide frame. Both optical concepts are robust against colour desaturation caused by ambient lighting, which can occur on exposed surfaces behind transparent outer lenses. This is achieved through various measures to reduce white light scattering. The concepts can be directly transferred to the front of the vehicle to implement position light and turn indicator combinations. A trend in automotive lighting is the increasing pixelation of light signatures [8,9]. In addition to segmentation of surface light guides, the combination of surface light guides with mini- or micro-LEDs is the next logical step. Meanwhile, several technologies for flat micro-LED panels are available on the market or currently in development, c.f. [10]. 11 ISAL 2025 – Proceedings Adaptive Signaling 8. References [1] C. Li et al., “Prism-pattern design of an LCD light guide plate using a neural- network optical model”, Optik - International Journal for Light and Electron Optics, 121, 2245-2249, 2010. [2] T. Gloss et al., “SurfaceLED”, ISAL Proceedings 2017, volume 17, utzverlag GmbH, 2017. [3] M. Kruppa et al., “DIGITAL OLED for Taillighting – Most Efficient, Homogeneous, and Flexible Display Technology”, ISAL Proceedings 2019, volume 18, utzverlag GmbH, 2019. [4] PLEXIGLAS Edgelight polymers: https://www.plexiglas- polymers.com/en/plexiglas-edgelight [5] PLEXIGLAS Edgelight 8N LD12 datasheet [6] T. Gloss et al., “Micro Surface-LED | Evolution of the S-LED Concept”, ISAL Proceedings 2019, volume 18, utzverlag GmbH, 2019. [7] M. Vollmer et al., “FlatLight-Technologies enabling new stylings for automotive signal lighting”, ISAL Proceedings 2021, volume 19, utzverlag GmbH, 2021. [8] C. Studeny, “New Trends and Functionalities in Signal Lighting”, ISAL Proceedings 2019, volume 18, utzverlag GmbH, 2019. [9] M. Vollmer, D. Duhme, “Beyond Lighting – How Exterior Displays Enhance Visual Communication on the Road”, Proceedings of the 15th International Symposium on Automotive Lighting, WBG Publishing Services, 2023. [10] E. Lang, U. Hiller et al., “Adaptive signal lighting – Breakthrough technology in LED area lighting and energy saving aspects.”, Proceedings of the 15th International Symposium on Automotive Lighting, WBG Publishing Services, 2023. [*] Image source: https://www.netcarshow.com/ 16. International Symposium on Automotive Lighting Darmstadt, 22. – 24. September 2025 Article DOI: 10.26083/tuprints-00030870 DOI (proceedings): 10.26083/tuprints-00030825 ISAL 2025 – Proceedings 12 This article is licensed under CC BY 4.0. https://creativecommons.org/licenses/by/4.0/ Adaptive Signaling An Efficient Projector Concept to Meet the Challenge of Signal Road Projection at Daytime T. Hornung1 1: odelo GmbH, Hedelfinger Straße 137, 70329 Stuttgart, Germany 1. Abstract The projection of a reversing symbol or a turn indicator symbol onto the road has been demonstrated to increase the visibility of the signal to other road users, thereby potentially mitigating the occurrence of accidents. However, for the projected symbol to be clearly visible and effectively capture the attention of other road users, it must stand out against the background illumination with high contrast. This task is readily achievable during nighttime hours when ambient illumination is minimal. However, it becomes increasingly challenging during daytime hours when the surrounding natural light exceeds 10 000 lx. odelo has developed a highly efficient signal projector capable of generating a road projection with luminous intensity values reaching the legal maximum stipulated in proposed regulations. The turn indicator signal projected by the device has a luminous intensity of 2 500 lx o 3 000 lx, ensuring visibility even during daylight hours, particularly in overcast conditions or shaded areas on sunny days. The device's compact design allows for integration into headlamps or rear combination lamps. The system's high efficiency reduces power consumption to levels that enable passive cooling, a crucial requirement for integrating it into tail lamps. Keywords: Signal Road Projection, SRP, Near Field Projection, Imaging Optics, Signal Lighting, Turn Indicator, Reversing Lamp 13 ISAL 2025 – Proceedings Adaptive Signaling 2. Introduction Cars use signal lights to indicate their intended actions to other road users. This is critical for road safety and helps mitigate accidents. Unfortunately, there are some situations in which a car's signal is not visible to another road user who needs to see and react to it. To address these issues and increase road safety, one proposed solution is to project signals onto the road. First, this paper examines the influence of mounting positions on the optical efficiency of signal road projectors. Next, we discuss the ambient lighting conditions in which road projections can contribute to road safety. Based on this, we determine the minimum illumination values that a signal road projection system must deliver to create a signal likely to be noticed by other road users. We then present a highly efficient optical solution for a projection system that provides the necessary illumination. Finally, we present our prototype signal road projector, which is small enough to be integrated into automotive signal lamps. Its performance is documented by laboratory measurements and outdoor photographs. 3. Mounting position An obvious way to add a signal road projector system to a car is to integrate it into the head and tail lamps. The outer lens of the lamp protects the projection system from the environment. Additionally, the lamp has an electric power connection, and the projection system can be controlled via the lamp’s communication interface with the car's central control unit. Designing an efficient optical system is more challenging when high luminous intensity is required because projecting light into a small solid angle brings the system closer to the limit of étendue conservation. Therefore, it is beneficial to position the projector in a way that minimizes the luminous intensity required to achieve the necessary level of illuminance. In general, it is favorable to maximize the ratio of illuminance on the road to the luminous intensity needed to achieve this illuminance. This ratio is inversely proportional to the square of the projection distance. The position of the car’s signal lamps at the corners of the car minimizes the lateral projection distance. The shorter the projection distance, the lower the luminous intensity needed to achieve the desired illuminance on the road. A lower mounting height also reduces the total projection distance for a given horizontal distance on the road. However, a lower mounting height increases the incident angle on the road surface, decreasing the illuminance according to the cosine law. Therefore, there is an optimal mounting height that maximizes the illuminance-to-luminous-intensity ratio for a given projection distance. Figure 1 shows the optimal mounting height for a projection system as a ISAL 2025 – Proceedings 14 Adaptive Signaling function of the horizontal distance of the projected signal on the road. The optimal projection angle is approximately 35° to the horizontal, independent of the projection distance. The typical height of a head or tail lamp seems very reasonable for an efficient signal road projection. Figure 1: Mounting height above the road level that maximizes the illuminance- to-luminous-intensity ratio as a function of the horizontal distance between the projector's position and the projection on the road. 4. Ambient lighting and required illuminance Several studies have been conducted on the visibility limit of a projected symbol on the road. A typical parameter to describe the visibility of a projected symbol is the Weber contrast 𝐶 = (𝐿𝑠 − 𝐿𝑎) 𝐿𝑎 = 𝐿𝑝 𝐿𝑎 where La is the ambient illumination, Ls is the total illumination within the projected symbol, and Lp is the illumination the signal road projector would generate without any ambient illumination. The visibility limit of a bright-to-dark contrast depends on several parameters, including ambient illumination, symbol size, presentation time, and observer age. [1] Certainly, the visibility limit is far from clearly visible. What we consider a clearly visible road projection is subjective and influenced by the surrounding situation. To simplify the matter, it is considered that a Weber contrast C five times higher than the visibility limit is clearly visible. We use Table 1 to determine the minimum illuminance that a signal road projector needs to generate in order to improve road safety. Reversing lamps are typically designed to support the reversing camera by illuminating the road surface behind the vehicle. 15 ISAL 2025 – Proceedings Adaptive Signaling Consequently, the illuminance generated by a conventional reversing lamp is often in the range of 3 lx to 5 lx. It seems unlikely that a signal projection would significantly benefit road safety if the light from a conventional reversing or turn indicator is already clearly visible on the ground. The first relevant usage scenario in Table 1 that exceeds this level is twilight. Therefore, a signal road projection should have at least 150 lx. Table 1: Ambient illumination situations and their typical illumination values and visibility limits, taken from [2]. The last column of the table shows the illumination level Lp that a signal projector needs to generate to produce a Weber contrast C five times greater than the visibility limit. Ambient condition Ambient Illumination [lx] Visibility limit projection [lx] Clearly visible projection [lx] Moon light 0,3 0,6 3 Streetlights 9,5 1 5 Driving beam 15 1,2 6 Twilight 750 30 150 Overcast sky 19 000 600 3 000 Direct sunlight 90 000 2 000 10 000 ISAL 2025 – Proceedings 16 Adaptive Signaling Figure 2: Color scale image of the maximum possible illuminance on the road that can be achieved by a signal road projection system without exceeding the 12 000 cd luminous intensity limit set by currently proposed legal regulations. In the image, all illuminance values above 5000 lx are colored red. The position of the turn indicator symbol projected by our prototype is marked in light gray. Figure 3: The intended shape and dimensions of the projected signal. It consists of three chevron-shaped segments. Each segment can be activated individually to create a swiping animation. The legal regulations set the upper limit of the luminous intensity of the light emitted by the projection system at 12 000 cd [3, 4]. Figure 2 shows how it limits the illuminance generated by a signal road projector mounted 800 mm high. A projection that is clearly visible on overcast days (3 000 lx) is only legal at distances up to 1 200 mm away from the projector (measured horizontally, parallel to the road surface). A projection that is visible in full sunlight (10 000 lx) would only be legal at a distance of approximately half 17 ISAL 2025 – Proceedings Adaptive Signaling a meter from the car. A projection at this short distance from the car is unlikely to improve road safety. In short, higher illumination increases the visibility of the projection and the ambient conditions under which it is visible. An illumination of more than 3 000 lx is desirable because it extends the use case to the daytime, including overcast days and shaded areas. This extends the operating time from the short periods of dusk and dawn to all day. However, a system that creates more than 3 000 lx conflicts with legal regulations at reasonable projection distances. The goal is obviously a projection system that projects a signal with an illuminance of around 3 000 lx onto the road. 5. Projector setup We set the mounting height of the signal road projector system to 800 mm above the road level for its development. The projector displays a yellow turn signal on the road. Figure 3 shows the intended shape of the signal projection. The signal consists of three chevron- shaped segments that can be activated sequentially to generate a swiping animation. Its width is 170 mm, and its total length is 800 mm. The projection begins at 575 mm from the exit aperture of the projector measured horizontally parallel to the road. Consequently, the tip of the last chevron shaped segment is a horizontal distance of 1 375 mm away. To ensure the signal road projector can be integrated into a car's tail lamp or head lamp, the exit aperture size was set to 20 x 20 mm². The entire optical system, Figure 4: Schematic visualization of the optical setup of a classical projector system. A condenser lens collects the light from the light source. A slide or gobo blocks light in certain areas to form an image. Finally, projecting optics project this image onto a screen. including the LED light sources and PCB, should be less than 50 mm long. Additionally, active cooling is not an option for tail lamps, so the system must perform efficiently enough to be cooled passively. ISAL 2025 – Proceedings 18 Adaptive Signaling As mentioned in Section 4, the goal is to achieve illuminance values of 3 000 lx in areas where legal regulations permit. In the remaining areas, the maximum legal luminous intensity of 12 000 cd shall be reached. 6. The optical system As shown in Figure 4, a classical projector setup consists of four elements. First, a light source generates light. Next, collimator optics collect as much light as possible and direct it onto an image-forming element, such as a slide or gobo. A projecting lens system then projects the image onto a screen. A gobo is a stop with one or more apertures that form a black-and-white image, while a slide can create a grayscale or color image. The underlying optical principle is the same for both types. They create an image by blocking unwanted light. The condenser usually illuminates a circular area. The greater the difference between the intended image and the circular illuminated area, the more light is blocked by the slide or gobo. This often eliminates more than 50 % of the light. One of the most important levers for creating an efficient signal road projector is reducing this light loss at the slide or gobo. The solution we developed does not use slides or gobos. Instead, light guides form the image as shown in Figure 5. The contour of the exit aperture of each light guide shapes a segment of the intended projection. The optical setup uses several LED light sources which increases the available luminous flux. The light guides maximize light collection from the LEDs and direct the light efficiently to the areas Figure 5: Schematic visualization of the optical setup of the odelo signal road projector. The light from the light sources is fed into light guides that form an image based on their outer geometry. Finally, a projecting lens system projects this image onto the road. where it is needed for the projection. Having one LED per projection segment also facilitates generating a homogeneous projection on the ground. Adjusting the current through an LED changes the illuminance of the corresponding part of the projection. 19 ISAL 2025 – Proceedings Adaptive Signaling This allows segments close to the car to be dimmed to reduce inhomogeneity. Of course, this optical setup natively allows for segment-by-segment animation of the projection. 7. Measurement results Figure 6 shows the prototype of the model signal road projector with a 2 Euro coin for size comparison. A photo of the projected turn indicator signal is shown in Figure 7. To achieve more homogeneous illumination, the segments closer to the car operate at reduced power. The illuminance of the two chevron-shaped segments closest to the car reaches values between 2 500 lx to 3 000 lx. The chevron-shaped segment at the far end of the projection reaches illuminance levels of 2 000 lx to 2 500 lx. According to the findings in Section 4 these illuminance values ensure good visibility of the projected symbol on overcast days or in shaded areas. Figure 8 demonstrates this on a sunny winter day. The goniometer scan of the luminous intensity emitted by our prototype (Figure 9) shows that the luminous intensity of the distant projection segment still exceeds the proposed legal limit. For integration into a car, the luminous flux of the corresponding LED must be reduced. Our measurements show a total luminous flux within the projection area of over 250 lm. Considering that the system uses three high-power yellow LEDs, the average optical efficiency is more than 30 %, with the segment closer to the car being more efficient than the segment farther away. Figure 6: Photo of the odelo signal road projector prototype with a simple 3D- printed housing. The exit aperture measures 2 x 2 cm², and the length without the heat sink is 45 mm. ISAL 2025 – Proceedings 20 Adaptive Signaling Figure 7: Photo of the projected light signal on a white surface. 8. Summary Making a signal road projection visible during the day extends the time period during which it can provide safety benefits from a few hours at dusk and dawn to all day. To achieve this, the illuminance of the road projection should be close to 3 000 lx. Higher illuminance values are not useful due to luminous intensity limits set by legal regulations. We have developed an optical solution that uses light guides to greatly increase the projector's optical efficiency. Our signal road projector prototype has an aperture of 20 x 20 mm² and a length of 45 mm. It creates a uniformly illuminated turn indicator projection consisting of three chevron-shaped segments with an illuminance of up to 3 000 lx. Measurements verify an average optical efficiency of over 30 %. The projected symbol is clearly visible in the shade during the day. Figure 8: Photo of the signal road projection in the odelo parking lot in the shade on a sunny winter day. This photo was taken at 4 p.m. on February 3, 2025. No adjustments or manipulations have been applied to the photo, except for obscuring the license plate. 21 ISAL 2025 – Proceedings Adaptive Signaling Figure 9: Measured luminous intensity distribution of the odelo signal road projector, displayed on a linear color scale ranging from 0 to 14 000 cd. 9. References [1] T. Schlürscheid; A. Stuckert; A. Erkan, and T.Q. Khanh, “An Analysis of Visibility Requirements and Reaction Times of Near-Field Projections,” Applied Sciences, MDPI, Basel, Switzerland, 14(2) 872, 2024: https://doi.org/10.3390/app14020872 [2] G. Kloppenburg, Scannende Laser-Projektionseinheit für die Fahrzeugfrontbeleuchtung, Dissertation, Universität Hannover, 2017 [3] International Automotive Lighting and Light-Signalling Expert Group (GTB), “Proposal for a Supplement to the 01 series of amendments to UN Regulation No. 148 and to the 06, 07, 08 and 09 series of amendments to UN Regulation No. 48,” United Nations Economic Commission for Europe, Geneva, 2025 [4] GB 5920-2024, “Light-signalling devices and systems for motor vehicles and their trailers”, National Standardization Management Committee, China, 2024 16. International Symposium on Automotive Lighting Darmstadt, 22. – 24. September 2025 Article DOI: 10.26083/tuprints-00030868 DOI (proceedings): 10.26083/tuprints-00030825 ISAL 2025 – Proceedings 22 This article is licensed under CC BY 4.0. https://creativecommons.org/licenses/by/4.0/ Adaptive Signaling ADS Marker Lamps – Results of Field Testing and Customer Studies Daniel Betz1, Alexander Bohn1, Stephan Muecke1, Stephanie Seupke1, Nikolas Sciortino2 1: Mercedes-Benz AG, 71059 Sindelfingen, Germany 2: Mercedes-Benz R&D North America, Inc., Farmington Hills, Michigan 48331, USA 1. Abstract ADS marker lamps have been defined to display a Level 3 driving mode of an automated driving system (ADS) towards other road users. The status of the corresponding regulation differs depending on the respective market. This paper aims to provide an updated overview of the current situation. It will be interesting to note, if there is a path towards a worldwide unified regulation. Mercedes-Benz has conducted customer studies to evaluate the customer needs and customer feedback on ADS marker lamps. The results show high interest and positive feedback for this new technology, and they underline the benefits for both, drivers and traffic authorities. Furthermore, Mercedes-Benz performed several field tests on public roads in the United States and Germany by using a specially equipped test fleet. We evaluated the interaction of other road users with Level 3 vehicles deploying ADS marker lamps. The results of our field tests show that their activation does not impede traffic or cause unnecessary risk to other road users. Keywords: Autonomous Vehicle (AV), Lighting and Communication, Regulations and Standardization 23 ISAL 2025 – Proceedings Adaptive Signaling 2. Introduction Assisted and automated driving systems have been categorized into five different levels [1], see also Figure 1. For Level 1 and 2 we refer to as assisted driving systems. Which means the driver is still in full control of the vehicle. Starting with Level 3 the picture becomes completely different. Now the driving system is in full control of the vehicle. This comes along with several technical requirements for the driving systems. This is why the system has a redundant design, which means that important functions such as electrics, steering and braking are built in twice. Under Level 3 conditions the driver is allowed to enjoy other activities such as working or reading the news on the media display. But the driver must be able to take over the driving task again in a short time. Figure 10: Five Levels of assisted and automated driving systems. For other road users such as other drivers, pedestrians and cyclists it will be beneficial and useful to distinguish between a Level 2 and a Level 3 driving mode system. Inattentiveness of the driver could lead to a dangerous situation in a Level 2 driving mode. Whereas for a vehicle in Level 3 driving mode the situation is fully under control by the system and there is no need to worry for others. In addition, clear recognition of an automated driving condition plays an important role for law enforcement representatives and traffic authorities. The aim is to facilitate effective enforcement of distracted driving laws, e.g. that an officer knows that doing other activities while driving is legal at the time of observation. Hence, authorities worldwide have come up with ideas to regulate the indication of Level 3 driving modes. Turquoise marker lamps for automated driving systems have been under consideration and discussion over the last few years. ISAL 2025 – Proceedings 24 Adaptive Signaling 3. Status of Regulatory Activities Despite ongoing activities no regulation on a nationwide level is prescribed so far. The SAE (Society of Automotive Engineers) has introduced their recommended practice J3134 already in 2019. A draft for a GB Standard (Guobiao Standard) has been published in China but was withdrawn in 2024. For UNECE (United Nations Economic Commission for Europe) the Taskforce AVSR (Autonomous Vehicle Signalling Requirements) has been installed in 2018 and has published a first draft of technical characteristics in October 2024 [2]. SAE is currently evaluating an updated version of their 2019 document [3] and in China a new drafting process for GB 4785 has started in 2025. It is interesting to note that some regions in China have released local regulations, e.g. for Beijing and Shenzhen. As discussed at ISAL 2023 and at SIA Vision 2024 [4, 5] the current versions of the drafted standards are very similar regarding technical specifications. Some basic principles about installation position and the chromaticity of the ADS marker lamps seem to be of common ground. Further requirements regarding intensities and light distribution are still under consideration and it is not clear whether it ends up with harmonized or individual solutions. It will be interesting to follow the further work of the expert groups in relevant markets. To support the decision on ADS marker lamps at UNECE level, Japanese experts have presented the results of an online survey at the 92nd GRE (Working Party on Lighting and Light-Signalling) in April 2025 [6]. The survey was conducted in Japan, the UK, the US and Germany among drivers regarding their opinions on the necessity and mounting method of ADS marker lamps. The experts found out that in all countries the respondents are positive about the introduction of marker lamps, with negative responses accounting for less than 10% in all four countries. The most common reasons that have been mentioned for introducing marker lamps were that the lamps make it possible to anticipate the movements of an automated driving vehicle and that the lamps are necessary for police enforcement to indicate the status of the ADS. Negative opinions against the marker lamps mentioned a general mistrust in automated driving vehicles, concerns about pranks and interference and concerns about theft. 25 ISAL 2025 – Proceedings Adaptive Signaling 4. Online Customer Survey Mercedes-Benz has become the world’s first automotive company to achieve Level 3 permission for its DRIVE PILOT system for passenger cars. This holds for certain versions of the EQS and S-Class in Europe and individual States of America such as California and Nevada. As a safety pioneer in automotive engineering Mercedes-Benz also supports the idea of signalling the driving status with specific ADS marker lamps. Especially for the US market Mercedes-Benz developed a questionnaire that aimed to gauge public acceptance of these marker lamps if permitted in the US. A special focus was placed on participants from California. California is one of the hot spots of automated driving in the US, as several providers of autonomous vehicles have their products already on the road. Our study collected data from December 2024 to March 2025, involving 873 California residents, 894 residents from other US-states, and 39 law enforcement officers from across the US. In the questionnaire for general road users, there were 873 participants from California (51% female, 49% male) and 894 participants from various other U.S. states (51% female, 47% male). When asked, "How do you rate the idea of making it recognizable that a car is driving in automated mode?" 63% responded favourably, while 23% expressed a neutral stance, see Figure 2. Participants saw an increased safety as the main benefit although some of them expressed general concerns about the concept of automated driving. When comparing responses between California participants and those from the rest of the U.S., no significant difference was observed. Figure 11: Response from prompt: “How do you rate the idea of making it recognizable that a car is driving in automated mode?” When participants were asked specifically about the perceived safety benefits and support for ADS marker lamps, over 40% expressed strong support for this technology, as illustrated in Figure 3 (Top 2 values in % on question a)). Participants from California ISAL 2025 – Proceedings 26 Adaptive Signaling were slightly more inclined to agree that the ADS marker lamps provide a safety benefit (Top 2 Values in % on question b)). Only a minority of less than 16% expressed concerns about the marker lamps (Top 2 Values in % on question c)). Figure 12: Response breakdown between California and rest of the US Participants were asked the question, "How do you rate the idea of making it recognizable that a car is driving in automated mode?" twice—once at the beginning and again at the end of the survey. The results indicate that opinions on the ADS marker lamps were more positive in the second assessment (Figure 4). Figure 13: Comparison of first and second rating results Like the general road user questionnaire, law enforcement participants were asked, "How do you rate the idea of making it recognizable that a car is driving in automated mode?" twice—once at the beginning and again at the end of the questionnaire. The results indicated that law enforcement officers showed slightly greater support for the ADS marker lamps in the second assessment. Figure 4 also reveals that 71% of participants are supporters of ADS marker lamps, while 12% can be regarded as opponents. The analysis showed high approval for the visibility, design, and function of the ADS marker lamps to convey automation status information. 27 ISAL 2025 – Proceedings Adaptive Signaling Key Findings of Online Survey The questionnaire study targeted two primary sample populations: general road users and law enforcement. Both groups perceived the ADS marker lamps positively, recognizing their role in conveying transparency and providing a safety benefit. The results indicate that both groups do want to know when an ADS is engaged, and these ADS marker lamps effectively address this need. The design of the ADS marker lamps received favourable ratings, with minimal concern about their potential to distract drivers on the road and minimum risk of confusion with other lighting signals. Initial concerns regarding ADS marker lamps stemmed from a lack of understanding and confusion about their purpose. These issues could be mitigated through educational initiatives implemented before and during the market introduction. 5. On-Road Studies Mercedes-Benz conducted two on-road studies: One in the US and one in Germany to evaluate real life traffic behaviour for vehicles equipped with ADS marker lamps. To collect on-road data, Mercedes-Benz equipped seven EQS test vehicles with ADS marker lamps. All the test vehicles were previously equipped with DRIVE PILOT, Mercedes- Benz's Level 3 conditionally available automated driving system. Figure 5 displays how the ADS marker lamps were integrated into the headlights, side mirrors (turn indicator) and rear taillights (turn indicator). The ADS marker lamps would only be active if the vehicle was being driven in an automated mode. Figure 14: ADS marker lamps integrated into an EQS headlight, side mirror and taillight. It is important to note that for the US study, the test fleet operated in a speed range up to 40 mph (appr. 60 km/h) for the automated driving system. In Germany, where Mercedes- Benz has allowance for a higher speed of the Level 3 system, the tests took place at speeds up to 95 km/h. For the US on-road study the data was gathered by five vehicles. Each vehicle was able to drive in Level 3 mode with ADS marker lamps switched on and off. For the German ISAL 2025 – Proceedings 28 Adaptive Signaling on-road study there were two test vehicles. The test vehicles always had the marker lamps switched on in ADS mode. To be able to compare the marker lamps off and on modes, the test vehicles were conducting their tests in a tandem operation, which means that there was always a second vehicle on the road, collecting the “lights-off” mode data. 5.1. US On-Road Study The US study took place in California, where two tests were conducted using the gathered on-road data. A total of 322 hours of data was collected in Level 3 mode for this study, with 180.8 hours recorded while ADS marker lamps were on and 140.8 hours with the lights off. Test 1 focused on analysing the following distance data. The objective was to determine if other drivers follow more closely when automated vehicle operations are accompanied by ADS marker lamps. The data acquisition system measured the following distances expressed in seconds. The null hypothesis posited that there is no difference in following distance between automated vehicles with ADS marker lamps activated and those without. Test 2 centred on "aggressive driving events." The aim was to identify whether other drivers exhibit more aggressive driving behaviours in the presence of automated vehicles with ADS marker lamps active. To capture these events, the data acquisition system recorded instances where the subject vehicle experienced a harsh brake event (e.g., a brake check) or a cut-in from a neighbouring lane vehicle. The parameters of this test involved analysing the total event count and filtering out events not deemed to be provoked by aggressive driving. The null hypothesis stated that there would be no significant difference in driving behaviour between automated vehicles with ADS marker lamps activated and those without. Figure 6 shows the results from Test 1 after collecting data for 87 hours lights off and 109 hours light on. The distance to the following vehicle has been categorized in different ranges from 0 to 2.5 seconds. Distances more than 2.5 seconds have not been considered. The distribution shows the differences between the situation with marker lamps “on” (green bars) and marker lamps “off” (orange bars). The graph displays a decrease in percentage for marker lamps “on” at lower distances (< 1.75 s) compared to an increase in percentage at higher distances (> 1.75 s). Showing that the distance between the subject and the following vehicle increases when the ADS marker lamps are “on”. 29 ISAL 2025 – Proceedings Adaptive Signaling Figure 15: Distance distribution to following vehicles On average, vehicles following the subject vehicle with ADS marker lamps engaged maintained a greater following distance, with a total headway of 1.65 seconds (49.5 feet) compared to 1.69 seconds (48.4 feet) when the ADS Marker Lights were off. Across the entire dataset and various speed ranges, the mean variance remains statistically significant, validating the finding that following distances increase when the ADS marker lamps are active. The findings from Test 2 in Table 1 showed that there was a recorded 0.26 aggressive driving events/hour with lights off and 0.29 events/hour with lights on. The analysis of variance shows that there is no statistical difference between these two values at the 95% confidence level – essentially, driving behaviour is the same. Marker Lamps Off Marker Lamps On Total number of events 36 52 Sample Hours 140.79 180.74 Events/Hour 0.26 0.29 Table 1: Aggressive Driving Events, Data Overview The results from Test 1 demonstrated that when ADS Marker Lights were activated, trailing vehicles maintained a greater following distance, specifically 1.1 feet more than when the ADS Marker Lights were off. Although this increased distance does not directly translate to an immediate safety benefit for the occupants of the automated vehicle, it suggests a positive behavioural response from other drivers. The presence of ADS Marker Lights could have the ability to mitigate the risk of aggressive engagement by other drivers, potentially enhancing the overall safety environment around automated ISAL 2025 – Proceedings 30 Adaptive Signaling vehicles. This finding highlights the importance of visual cues in influencing driver behaviour and supports the notion that ADS Marker Lights can contribute to a more harmonious interaction between automated and conventional vehicles on the road. The results from Test 2 show that there is no effect on aggressive behaviour. This can be interpreted that while road users may increase distance between themselves and the ADS Marker Light vehicle, there was no increase in aggressive behaviour in forms of cut-ins, or brake checking. 5.2. German On-Road Study For the German study also two tests were conducted using the gathered on-road data. The focus was on the situation when the ADS marker lamps have been switched on. A total of 335 hours of data was collected in Level 3 mode for this study, with 169 hours recorded while ADS marker lamps were on and 165 hours with the lights off. Test 1 was carried out to analyse the following distance data. The trigger point was the moment when the subject vehicle activated its Level 3 ADS system. The objective was to find out, whether the following traffic reacts differently when the ADS marker lamps are switched on additionally. The null hypothesis posited that there is no difference in following distance directly after system activation between automated vehicles with ADS marker lamps activated and those without. Test 2 centred on driving events that occurred when the vehicle was in Level 3 mode and ADS marker lamps were activated. The drivers have been asked to note any remarkable event that came to their notice. This means that there was no special focus on “aggressive” driving events, but open to any behaviour of the surrounding traffic that seemed to be related to the activation of the ADS marker lamps. The recorded events have then been analysed by our experts for automated driving and have been categorized whether they belong to a critical or uncritical behaviour. The null hypothesis posited that there are no critical events related to activation of ADS marker lamps. 31 ISAL 2025 – Proceedings Adaptive Signaling Figure 16: Distance Change two seconds after ADS activation Figure 7 displays the results from Test 1 in Germany. It shows the change in distance of the following car after the activation of the ADS Level 3 system in seconds. The x-axis shows the speed segments (0-95 km/h). The figure shows how the distance changes for vehicles without and with activated marker lamps. A trend can be identified as for higher speeds (> 60 km/h) the following distance gets smaller. For lower speeds there is no clear trend in the data. It is interesting to note, that for higher speeds the distance decreases for both vehicles with light on and off. This can be understood if we look at the behaviour of the Level 3 ADS system. The system always seeks to increase the distance to the front vehicle in a first step. This inevitably leads to a smaller distance to the following vehicle. The aim of the study was to find out whether there is a change in this behaviour depending on the status of the marker lamps. Looking at the data in Figure 7 it turns out that no difference can be detected within the fault tolerance. Furthermore, the analysis of variance shows no significant difference in the data. In a second evaluation the situation four seconds after the activation of the marker lamps has been analysed. The results were similar to the two second observation. Hence, we can conclude that there is no influence of the ADS marker lamps on the following distance directly after activation of the lights. It can further be concluded that there is no negative influence on the following traffic by switching on the ADS marker lamps. Figure 8 shows the categorization of the driving events that occurred when ADS marker lamps have been switched on. ISAL 2025 – Proceedings 32 Adaptive Signaling Figure 17: Classification of driving events The analysis of the events shows different categories of events. 52% of the events included remarks about the distance of the following vehicle. The drivers stated that although the lights have been switched on, no increase in the distance of the following vehicle has been observed. This result is in good accordance with the previous findings of Test 1. There was one event mentioned, where the driver observed an increase in distance which was stated as “benefit”. 26% of the events were related to glances of the occupants of passing by cars. At five occasions (16%) it appeared that the overtaking vehicles slowed down to observe the vehicle with ADS marker lamps. And there was one case where the driver of the following car took some photos and showed gestures towards the subject vehicle. To sum up, the classification of the data so far supports our null hypothesis that there a no critical events related to activation of the marker lamps. Although the classification of the above-mentioned events is not completed yet. So far only half of the time of the 169 hours of driving has been analyzed in detail. But even for the complete time, none of the test drivers has reported any critical event yet. A full picture of the study will be given at the ISAL conference. 6. Summary and Outlook Our studies provided valuable insights into the relationship between external indicators for automated driving (ADS marker lamps) and road user interaction. The findings from the questionnaire studies reveal that the public generally supports ADS Marker Lights and appreciates their ability to convey a vehicle's automation status The on-road studies in the US and in Germany demonstrated that ADS marker lamps do not introduce additional safety risks. In fact, the data indicated that road users maintain a greater following distance when these Lights are active and do not result in more aggressive driving events. This is very remarkable as the potential of road rage or aggressive behaviour is one of the most mentioned concerns people express in online surveys. But real-life experience so far demonstrates that these risks seem to be very small indeed. As a global car manufacturer Mercedes-Benz supports the idea of harmonized regulations for an increased acceptance and confidence of other road users in the new 33 ISAL 2025 – Proceedings Adaptive Signaling technology of automated driving systems. We believe there is a need for an easy and intuitive signal understanding in road traffic and it should be the same signalling around the world. Mercedes-Benz will therefore carry on its on-road studies and will provide the insights of its testing results for experts working on future regulatory. 7. References [1] SAE International: Surface Vehicle Recommended Practice J3016, SAE Technical Standards, 2021 [2] Automated Driving Systems Marker Lamp (ADS ML), Informal document GRE-91-12, presented at 91st GRE, 22 - 25 October 2024 [3] SAE J3134 “Update on Five-Year Document Review Activity“, Informal document GRE-92-07, presented at 92nd GRE, 22-25 April 2025 [4] Betz, D. et al.: ADS Marker Lamps – Regulatory Requirements and Technical Implementations; ISAL Proceedings, 2023 [5] Betz, D. et al.: ADS Marker Lamps – Testing insights and activities towards harmonized regulations; SIA Vision Proceedings, 2024 [6] Survey of Opinions Among Drivers on the Introduction of Automated Driving System Marker Lamp, Informal document GRE-92-27, presented at 92nd GRE, 22-25 April 2025 ISAL 2025 – Proceedings 34 ADAS and Lighting for ADAS II. ADAS and Lighting for ADAS 16. International Symposium on Automotive Lighting Darmstadt, 22. – 24. September 2025 Article DOI: 10.26083/tuprints-00030859 DOI (proceedings): 10.26083/tuprints-00030825 35 ISAL 2025 – Proceedings This article is licensed under CC BY 4.0. https://creativecommons.org/licenses/by/4.0/ ADAS and Lighting for ADAS Potential Energy Savings of Adaptive Driving Beam Headlamps Using ADAS Sensors by Environmental Aware Lighting Control Yunji Heo1, Hyeran Kang2, Chan-Su Lee2, Jaebeom Lee1, Gilwon Han1 1: Hyundai Mobis, 17-2 Mabuk-ro 240beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 2: Yeungnam University, 280, Daehak-ro, Gyeongsan-si, Gyeongsangbuk-do 1. Abstract This study proposes a strategy to reduce power consumption in vehicle lighting systems, particularly headlamps, as part of efforts to improve energy efficiency in electric and eco-friendly vehicles. Among the various electrical components in a vehicle, lighting systems consume a significant amount of power, with low beams accounting for approximately 52% of total lamp energy usage. Therefore, this study presents an integrated control strategy that dynamically adjusts the power consumption of low and high beams according to real-time driving conditions, aiming to reduce energy use while maintaining driver visibility and safety. Experiments were conducted using simulation environments with 30 participants, based on three key variables: ambient illuminance, driving speed, and inter-vehicle distance. The results showed that in urban environments with high illuminance (above 50 lx), reducing low beam intensity to 25% did not compromise visibility or safety. At speeds above 80km/h, the use of high beams was found to be essential for maintaining sufficient visibility. Additionally, in scenario based on inter-vehicle distance, the presence of a leading vehicle allowed the Adaptive Driving Beam (ADB) system to further adjust light output. When applied to real-road conditions, low beam power consumption was reduced from 31.8W to 12.22W, achieving over 60% energy savings. This study is expected to be expanded through future research involving real vehicle testing and regulatory considerations. ISAL 2025 – Proceedings 36 ADAS and Lighting for ADAS Keywords: Matrix Head Lamp, Energy Saving, Ambient Light, Clearance, ADAS Sensor, Lighting Control Logic 2. Introduction With the growing need to address global warming and the increasing adoption of electric vehicles, improving energy efficiency across the automotive industry has become a critical issue. In particular, optimizing power consumption for each component of eco- friendly vehicles is emerging as a key challenge. Among the various electrical systems in a vehicle, lighting systems account for a significant portion of total energy consumption, with low and high beams being among the most power-intensive components [1]. Specifically, low beams account for more than 52% of lamp energy usage, and their cumulative power consumption is substantial due to continuous operation during nighttime or low-light driving conditions. Previous studies on low-power lighting have primarily focused on reducing light output [2] or using high-efficiency light sources such as LEDs [3]. However, these approaches are difficult to implement effectively without simultaneously considering driver visibility and safety. Therefore, this study aims to achieve both energy savings and visibility by dynamically controlling headlamps based on real-time driving conditions— ambient illuminance, vehicle speed, and inter-vehicle distance. To this end, the study establishes various control scenarios and quantitatively analyzes their effects through simulation-based experiments. Furthermore, the applicability of these scenarios to real-road conditions is evaluated, aiming to make a practical contribution to the design of lamp systems for eco-friendly vehicles. 3. Research Methods 3.1 Experimental Setup This study conducted experiments with 30 participants (aged 20s to 50s) based on three main control scenarios: - Scenario 1: Low beam light output control based on ambient illuminance - Scenario 2: ADB (Adaptive Driving Beam) control based on driving speed - Scenario 3: ADB control based on inter-vehicle distance The experimental environment was constructed using driving simulator software ANSYS AVxcelerate Headlamp (AVX) and AVSIMULATION SCANeR™ Studio. Participants performed visual detection tasks while their reaction time, obstacle detection 37 ISAL 2025 – Proceedings ADAS and Lighting for ADAS distance, and accuracy were measured. If the obstacle detection distance was shorter than the required stopping distance, it was judged as "Not OK" due to insufficient time to avoid the obstacle, and the light output was adjusted to ensure proper detection distance (see Figure 1). Additionally, an eye tracker was used to monitor the participants’ gaze positions to determine whether they were actually performing visual detection. The lighting system used a matrix beam composed of approximately 100 pixels, each of which could be individually dimmed (on/off). This allowed the system to reduce light in areas where visibility was unnecessary and maintain brightness where it was needed, enabling a highly flexible beam pattern configuration. In addition to performance metrics, participants were asked to evaluate the visibility and subjective preference of each beam pattern configuration. This allowed for a comprehensive assessment of both objective detection performance and user-perceived comfort and effectiveness. Figure 18: Experimental Environment and Visual Detection Task 3.2 Control Scenario Configuration 3.2.1 Low Beam Control Based on Ambient Illuminance The driving environment's ambient illuminance was set to three levels: 10 lx (suburban roads), 30 lx (general urban roads), and 50 lx (high-illuminance urban areas). Low beam brightness levels were configured as follows: 100% (based on Genesis luxury vehicle standard), 75%, 50% (legal regulation), 25%, and 0% (off). The driving speed was fixed at 40 km/h, representing typical urban driving conditions. Evaluation metrics included the recognition rate of ground-level obstacles located in the driving lane and pedestrians positioned on the right sidewalk (see Figure 2(a)). ISAL 2025 – Proceedings 38 ADAS and Lighting for ADAS 3.2.2 ADB Control Based on Driving Speed Driving speeds were set to 50 km/h, 80 km/h, and 110 km/h. Low beams remained constantly on, while high beam brightness was varied across four levels: 0% (Low beam only), 20%, 45% (legal regulation), and 100% (Genesis luxury vehicle standard). To minimize the influence of low beams, obstacles with a ground clearance of 70cm were placed, and recognition rates were measured not only in the vehicle’s own lane but also in the adjacent left and right lanes (see Figure 2(b)). 3.2.3 ADB Control Based on Internal-Vehicle Distance Driving speed was 110km/h, and inter-vehicle distances were set to 20 m, 40 m, 60 m, and 80 m. High beam brightness levels were configured to 25%, 50%, 75%, and 100%. This scenario aimed to evaluate how the presence of a leading vehicle affects peripheral light control. To do this, obstacles with a ground clearance of 70cm were placed in the left and right adjacent lanes, and recognition rates were measured (see Figure 2(c)). Figure 2: Configuration of the experimental environment (a) Scenario 1: low beam control based on ambient illumination (b) Scenario 2: ADB control based on driving speed (c) Scenario 3: ADB control based on internal-vehicle distance. 39 ISAL 2025 – Proceedings ADAS and Lighting for ADAS 4. Experimental Results Note: In Figures 3–5, the red dotted line indicates the braking distance on dry asphalt surfaces, the blue dotted line indicates the braking distance under snowy conditions, and the red circles represent the best-case scenarios where visibility and stopping distance were optimized under the given conditions. These references are provided once here to avoid repetition in individual figure captions. 4.1 Results of the Illuminance-Based Low Beam Scenario As ambient illuminance decreased, higher low beam brightness was required. For instance, as shown in Figure 3(b), in a 30 lx environment, obstacles with a height of 15 cm were not reliably detected when the low beam brightness was below the legal threshold. Therefore, maintaining the legal regulation (50%) was sufficient to ensure a safe stopping distance in both 10 lx and 30 lx conditions. In contrast, in the 50 lx environment, street lighting alone provided excellent recognition rates, and even when the low beam brightness was reduced to half the legal level, visibility was not compromised. Therefore, in high-illuminance urban environments (50 lx), especially during nighttime city driving, it is worth considering minimizing the low beam light output (see Figure 3(c)). ISAL 2025 – Proceedings 40 ADAS and Lighting for ADAS Figure 3: Comparison of stopping distances by object type according to ambient illumination and low beam light intensity variations. Braking distances at 40 km/h: 6 meters (dry asphalt), 21 meters (snowy asphalt). (a) a countryside road with an illuminance level of 10 lx (b) a regular street with an illuminance level of 30 lx (c) a commercial area with an illuminance level of 50 lx 4.2 Results of the Speed-Based ADB Scenario At speeds below 50 km/h, low beams alone were sufficient to secure a safe stopping distance (see Figure 4(a)). In this speed range, the use of high beams was not necessary. However, the use of high beams significnatly improved obstacle detection performance, particularly on the left side of the vehicle, compared to using low beams alone. The current legal standard for high beam brightness(45%) was found to be adequate under these conditions. For example, during snowy road driving at 80 km/h, high beams were necessary to maintain sufficient visibility (see Figure 4(b)). 41 ISAL 2025 – Proceedings ADAS and Lighting for ADAS At 110 km/h, even with high beams, maintaining a safe stopping distance became challenging, indicating a potential safety risk during snowy road (see Figure 4(c)). Figure 4: Comparison of stopping distances according to vehicle speed and ADB intensity variations. Braking distances in dry asphalt: 10m at 50km/h, 25m at 80km/h, 48m at 110km/h. Braking distance in snowy road: 33m at 50km/h, 84m at 80km/h, 159m at 110km/h. (a) driving speed of 50km/h (b) driving speed of 80km/h (c) driving speed of 110km/h 4.3 Results of the Inter-Vehicle Distance-Based ADB Scenario When the inter-vehicle distance is short, the the driver’s field of view is limited due to the presence of the leading vehicle, requiring brighter illumination of the surrounding area. In particular, at distances of 20 m, a significant portion of the driver’s view is obstructed by the leading veihicle, and the ADB system must maintain a light output of at least 75% to ensure sufficient visibility (Figure 5(a)). Conversely, when the distance exceeds 40 meters, the leading vehicle’s headlights contribute positivlely to visibility, allowing the ADB system to reduce its own light output further. At distances between 40 m and 80 m, the low beams of the leading vehicle serve as supplementary lighting, mitigating visual obstruction and enabling the optimal ISAL 2025 – Proceedings 42 ADAS and Lighting for ADAS light output to be reduced to as 25 (Figure 5(b)-(d)). Additionally, during snowy road conditions, it is necessary to maintain an inter-vehicle distance of at least 80 m to ensure a safe stopping distance. Figure 5: Comparison of stopping distances according to inter-vehicle distance and ADB light intensity variations. Braking distances at 110 km/h: 48m (dry asphalt), 159m (snowy asphalt). (a) a gap of 20 meters between vehicles (b) a gap of 40 meters between vehicles (c) a gap of 60 meters between vehicles (d) a gap of 80 meters between vehicles 5. Discussion 5.1 Analysis of Power Consumption Reduction In accordance with South Korean streetlight installation regulations, road surface illuminance (lx) is classified based on road type and the number of lanes. The classification is as follows: 43 ISAL 2025 – Proceedings ADAS and Lighting for ADAS 1. 10 lx: Alleyways or suburban roads at night (2 lanes or fewer) 2. 30 lx: General street lighting (between 2 and 4 lanes) 3. 50 lx: Bright street lighting in commercial or urban areas (4 lanes or more) To estimate traffic volume per illuminance zone, total road length and the proprtion of each illuminance level were anlyzed, applying weights based on the number of lanes [4]. Table 1 summarizes the road length and traffic volume ratio for each zone. Table 1: Traffic volume analysis by road type Ambient Lighting Type Road Length (km) Traffic Volume Ratio (%) 10 lx (suburban road) 34,440.9 14.13 30 lx (regular street) 40,875.9 39.57 50 lx (commercial area) 3,667.9 46.30 Experimental results from Scenario 1 demonstrated that maintaining the legally regulated 50% low beam intensity, which corresponds to a power consumption of 15.9 W, was sufficient to ensure a safe stopping distance in both the 10 lx and 30 lx zones. Furthermore, in the 50 lx zone, a reduced intensity of 25%, with a power consumption of 7.95 W, was found to be adequate for maintaining visibility. Based on these things, an adaptive low beam control strategy was proposed. By multiplying the traffic volume ratio (%) by the corresponding power consumption (W) for each zone, the total low beam power consumption under the proposed strategy was calculated. As a result, the overall low beam power consumption was reduced from 31.8 W to 12.22 W, achieving an approximate 62% reduction in energy consumption. 6. Conclusion This study proposed a practical and intelligen