Real Time Rendering of Atmospheric Scattering and Volumetric Shadows

International audienceReal time rendering of atmospheric light scattering is one of the most difficult lighting effect to achieve in computer graphics. This paper presents a new real time method which renders these effects including volumetric shadows, which provides a great performance improvement over previous methods. Using an analytical expression of the light transport equation we are able to render directly the contribution of the participating medium on any surface. The rendering of shadow planes, sorted with a spatial coherence technique, and in the same philosophy than the shadow volume algorithm will add the volumetric shadows. Realistic images can be produced in real time for usual graphic scenes and at a high level framerate for complex scenes, allowing animation of lights, objects or even participating media. The method proposed in this paper use neither precomputation depending on light positions, nor texture memory

A New Mathematical Development for Radiosity Animation with Galerkin

International audienceCombining animation and global illumination constitutes, at present, a true challenge in computer graphics, especially when light sources move in a complex scene because the entire illumination has to be recomputed. This paper introduces a new algorithm, based on the Galerkin method, which can efficiently manage any moving surface -even light source- to compute animation sequences. For each new frame of a sequence, we take into account the continuous property of the moves to determine the necessary energy differences between the previous global illumination solution and the new one. Based on a mathematical development of the form factor, this new approach leads to an efficient and simple algorithm, similar to the classical progressive refinement algorithm, and which computes animated sequence about three times faster

Colour-Difference Assessment for Driving Headlight Simulation

In high quality driving simulation applications, such as headlight simulation, colorimetric validity is essential. In virtual testing of headlight systems, it is important that the WYSIWYG (What You See Is What You Get) paradigm is respected for product quality headlight assessment. Indeed, if a slightly reddish orange colour is displayed instead of the typical orange of halogen lighting, the effect for driver comfort or traffic safety can be critical. The lighting specialist should accept a headlight which doesn't have the right colour. Previous studies have shown that there is a significant colour difference between virtual and real environments. Nevertheless, in virtual headlight testing the rendered colour fidelity has to fit industrial assessment. This study therefore deals with the colour-difference perceptibility that is the ability of an observer to detect a difference between two colours and, more precisely, on the acceptability of the perceived difference. We propose in this paper a psychophysical function for colour difference acceptability which fits well with the measured data. The colour acceptability function was implemented in a driving simulator for high validity headlight assessment. Driver acceptability experimentation was carried out using Renault's headlight driving simulation equipped with a fullcab and a 210° cylindrical display screen

Color-difference assessment and enhancement for driving headlight simulation

Real-time headlight simulation in driving conditions is used by most car manufacturers to assure the quality, cost, and delivery of headlight engineering design. An important parameter judged by the headlight assessment team is color restitution; indeed, this parameter has to meet the standard of “lamps for road vehicles.” Therefore, the goal of this study was the color assessment and enhancement of a driving headlight simulator. For this purpose, this study was conducted in two phases: the process of constructing two color acceptability scales that directly reflect the perception of two different populations (experts and “naive”), and the assessment of a method based on the chromatic adaptation transform (CAT) for reducing the color difference between real and virtual environments. In the first phase, we conducted two psychophysical experiments (i.e., one for each population), in which the observers had to report their degree of satisfaction about the color difference. These two experiments enabled the creation of two acceptability scales for headlight simulation. In the second phase, we compared the performance of different chromatic transformations; as a result of this comparison, we advise the use of the CAT02 transformation, in order to reduce the color difference for headlight assessment in driving simulation experiments.ANRT (Association Nationale de la Recherche et de la Technologie) and Renaul

Colour-Difference Assessment for Driving Headlight Simulation

In high quality driving simulation applications, such as headlight simulation, colorimetric validity is essential. In virtual testing of headlight systems, it is important that the WYSIWYG (What You See Is What You Get) paradigm is respected for product quality headlight assessment. Indeed, if a slightly reddish orange colour is displayed instead of the typical orange of halogen lighting, the effect for driver comfort or traffic safety can be critical. The lighting specialist should accept a headlight which doesn't have the right colour. Previous studies have shown that there is a significant colour difference between virtual and real environments. Nevertheless, in virtual headlight testing the rendered colour fidelity has to fit industrial assessment. This study therefore deals with the colour-difference perceptibility that is the ability of an observer to detect a difference between two colours and, more precisely, on the acceptability of the perceived difference. We propose in this paper a psychophysical function for colour difference acceptability which fits well with the measured data. The colour acceptability function was implemented in a driving simulator for high validity headlight assessment. Driver acceptability experimentation was carried out using Renault's headlight driving simulation equipped with a fullcab and a 210° cylindrical display screen

Colorimétrie appliquée à la simulation de phare de voiture

Afin d’optimiser les temps de conception d’un système d’une voiture (phare, système de freinage, etc.), les industries utilisent de manière de plus en plus régulière des logiciels de simulation et de Conception Assistée par Ordinateur (CAO). Ces derniers permettent la visualisation en temps réel de ces systèmes sous diverses conditions (analyse de la résistance à la pression, à la chaleur, etc.). Le Centre de Réalité Virtuelle et de Simulation Immersive (CRVSI) de Renault dispose d’outils de conception et de maquettage virtuel (CAVE, simulateur dynamique, etc.). Ces derniers s’intègrent dans le cycle de la conception des véhicules en offrant aux utilisateurs la possibilité d’interagir, en temps réel, avec des maquettes virtuelles. Dans le cadre spécifique de la simulation des phares d’une voiture, il est important d’étudier la représentativité des couleurs affichées. Il est en effet primordial que, pour un outil de validation, la restitution des couleurs soit au plus proche de la réalité physique (phare halogène, LED, Xenon, etc.). La colorimétrie offre plusieurs outils permettant de calculer une différence colorimétrique. Nous avons ainsi étudié l’uniformité colorimétrique des métriques CIE76, CIE94 et CIEDE2000 afin d’une part, de proposer des coefficients de pondération pour la teinte et la chroma et, d’autre part, de comparer les résultats de chacune afin de déterminer celle qui uniformise le mieux l’espace CIELAB pour la simulation d’éclairage

Color-difference assessment and enhancement for driving headlight simulation

Real-time headlight simulation in driving conditions is used by most car manufacturers to assure the quality, cost, and delivery of headlight engineering design. An important parameter judged by the headlight assessment team is color restitution; indeed, this parameter has to meet the standard of “lamps for road vehicles.” Therefore, the goal of this study was the color assessment and enhancement of a driving headlight simulator. For this purpose, this study was conducted in two phases: the process of constructing two color acceptability scales that directly reflect the perception of two different populations (experts and “naive”), and the assessment of a method based on the chromatic adaptation transform (CAT) for reducing the color difference between real and virtual environments. In the first phase, we conducted two psychophysical experiments (i.e., one for each population), in which the observers had to report their degree of satisfaction about the color difference. These two experiments enabled the creation of two acceptability scales for headlight simulation. In the second phase, we compared the performance of different chromatic transformations; as a result of this comparison, we advise the use of the CAT02 transformation, in order to reduce the color difference for headlight assessment in driving simulation experiments.ANRT (Association Nationale de la Recherche et de la Technologie) and Renaul

Augmented Reality Head-Up-Display for Advanced Driver Assistance System: A Driving Simulation Study

Research and technological advance in the field of Augmented Reality (AR) is growing rapidly (Mas, 2011). One of the new application domains is the automobile industry, linked to the necessary men machine aspects of Advanced Driving Assistance Systems (ADAS). Relevant road traffic as well as useful navigation or path planning information may be displayed using partially or totally the windshield surface thanks to these emerging technologies. However, the way road traffic, signs or vehicle information is displayed impacts strongly driver’s attention with increased mental workload and safety concerns. Research in perceptual and human factors assessment is needed for relevant and correct display of this information for maximal road traffic safety as well as optimal driver comfort. At Renault, research is carried out in a number of automotive AR domains: the used information type and visual grammar, visual perception for the displayed information (depth, localization), and real time mixed reality, that is matching virtual and real environment. The main goal of this presented experiment was to study whether head movement impacts AR depth perception and thus modifying displayed image quality and decreasing driver performance. For this purpose, a driving simulator experiment, carried out in the CAVE Immersive Integration Platform (P2I) Driving Simulator, we analyzed: driver head movements during different realistic situations, preferences scale in each specific situation, and thus with and without head tracked conditions. Primary data shows a strong preference for the tracked system condition and the statistical scale factor was very significant

Determinants of the access to remote specialised services provided by national sarcoma reference centres

BACKGROUND: Spatial inequalities in cancer management have been evidenced by studies reporting lower quality of care or/and lower survival for patients living in remote or socially deprived areas. NETSARC+ is a national reference network implemented to improve the outcome of sarcoma patients in France since 2010, providing remote access to specialized diagnosis and Multidisciplinary Tumour Board (MTB). The IGéAS research program aims to assess the potential of this innovative organization, with remote management of cancers including rare tumours, to go through geographical barriers usually impeding the optimal management of cancer patients. METHODS: Using the nationwide NETSARC+ databases, the individual, clinical and geographical determinants of the access to sarcoma-specialized diagnosis and MTB were analysed. The IGéAS cohort (n = 20,590) includes all patients living in France with first sarcoma diagnosis between 2011 and 2014. Early access was defined as specialised review performed before 30 days of sampling and as first sarcoma MTB discussion performed before the first surgery. RESULTS: Some clinical populations are at highest risk of initial management without access to sarcoma specialized services, such as patients with non-GIST visceral sarcoma for diagnosis [OR 1.96, 95% CI 1.78 to 2.15] and MTB discussion [OR 3.56, 95% CI 3.16 to 4.01]. Social deprivation of the municipality is not associated with early access on NETSARC+ remote services. The quintile of patients furthest away from reference centres have lower chances of early access to specialized diagnosis [OR 1.18, 95% CI 1.06 to 1.31] and MTB discussion [OR 1.24, 95% CI 1.10 to 1.40] but this influence of the distance is slight in comparison with clinical factors and previous studies on the access to cancer-specialized facilities. CONCLUSIONS: In the context of national organization driven by reference network, distance to reference centres slightly alters the early access to sarcoma specialized services and social deprivation has no impact on it. The reference networks' organization, designed to improve the access to specialized services and the quality of cancer management, can be considered as an interesting device to reduce social and spatial inequalities in cancer management. The potential of this organization must be confirmed by further studies, including survival analysis