We present a method for fast volume rendering using graphics hardware (GPU). To our knowledge, it... more We present a method for fast volume rendering using graphics hardware (GPU). To our knowledge, it is the first implementation on the GPU. Based on the Shear-Warp algorithm, our GPU-based method provides real-time frame rates and outperforms the CPU-based implementation. When the number of slices is not sufficient, we add in-between slices computed by interpolation. This improves then the quality of the rendered images. We have also implemented the ray marching algorithm on the GPU. The results generated by the three algorithms (CPU-based and GPU-based Shear- Warp, GPU-based Ray Marching) for two test models has proved that the ray marching algorithm outperforms the shear-warp methods in terms of speed up and image quality.
We extend GPU shape grammars [MBG∗12] to model highly detailed roofs. Starting from a consistent ... more We extend GPU shape grammars [MBG∗12] to model highly detailed roofs. Starting from a consistent roof structure such as a straight skeleton computed from the building footprints, we decompose this information into local roof parameters per input segments compliant with GPU shape grammars. We also introduce Join and Project rules for a consistent description of roofs using grammars, bringing the massive parallelism of GPU shape grammars to the benefit of coherent generation of global structures.
Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly ha... more Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right.
L'oeil humain, organe important dans le processus de la communication non verbale, ncessite une m... more L'oeil humain, organe important dans le processus de la communication non verbale, ncessite une modlisation anatomiquement correcte ainsi que des mthodes de rendu raliste; ce afin d'accrotre le ralisme des personnages virtuels. Les rcentes amliorations matrielles permettent dsormais le rendu de matriaux organiques complexes, tenant compte de critres anatomiques. Nous proposons une nouvelle mthode de modlisation de l'iris humain permettant de reconstruire la structure interne de celui-ci et de retrouver ses paramtres de diffusion partir d'une photographie d'oeil. Ainsi, nous prsentons une mthode de drefraction d'image d'iris. Nous modlisons l'iris suivant la representation du Subsurface Texture Mapping [1] qui permet de dcrire les variations d'paisseurs des diffrentes couches de l'iris. Nous proposons enfin une mthode de rendu raliste et temps rel de l'oeil humain en introduisant une fonction de rfraction qui permet de tenir compte de la rfraction de la lumire l'interface air/corne.
Fast global illumination computation is a challenge in several fields such as lighting simulation... more Fast global illumination computation is a challenge in several fields such as lighting simulation and computergenerated visual effects for movies. To this end, the irradiance caching algorithm is commonly used since it provides high-quality rendering in a reasonable time. However this algorithm relies on a spatial data structure in which nearest-neighbors queries and data insertions are performed alternately within a single rendering step. Due to this central and permanently modified data structure, the irradiance caching algorithm cannot be easily implemented on graphics hardware. This paper proposes a novel approach to global illumination using irradiance and radiance cache: the radiance cache splatting. This method directly meets the processing constraints of graphics hardware since it avoids the need of complex data structure and algorithms. Moreover, the rendering quality remains identical to classical irradiance and radiance caching. Our renderer shows an implementation of our algorithm which provides a significant speedup compared to classical irradiance caching.
Proceedings of the 16th International Conference on 3D Web Technology - Web3D '11, 2011
Figure 1: Our approach for adaptive streaming at multiple levels: planet-scale structuration, vis... more Figure 1: Our approach for adaptive streaming at multiple levels: planet-scale structuration, visibility-based occlusion culling, multiresolution meshes and textures, and adaptive reconstruction of procedural models.
Proceedings of the 3rd international conference on Computer graphics and interactive techniques in Australasia and South East Asia, 2005
We describe a generic solution for remote adaptive streaming and rendering of large terrains. The... more We describe a generic solution for remote adaptive streaming and rendering of large terrains. The challenge is to ensure a fast rendering and a rapidly improving quality with any user interaction, network capacity and rendering system performance. We adapt to these constraints so loading and rendering speeds do not depend on the size of the database. We can thus use any database with any client device. Our solution relies on a generic data structure to adaptively handle data from the server hard disk to the client rendering system. The same methods apply whatever is done with these data: only the data themselves and the rendering system vary. We base our data structure on existing solutions with good properties and add new methods to handle it more efficiently. In particular we avoid loading irrelevant or redundant data and we request the most important data first. We also avoid costly data structure operations as much as possible, in favor of "in-place" data updates and selection using sample masks.
Proceedings of the Digital Production Symposium on - DigiPro '12, 2012
Figure 1: Scenes from Wrath of the Titans (a) and Prometheus (b) involve extremely dense volumetr... more Figure 1: Scenes from Wrath of the Titans (a) and Prometheus (b) involve extremely dense volumetric objects. We adapt the Transmittance Function Mapping algorithm for high quality interactive previsualization and tuning of those media. Images: (a)
Figure 1: Comparisons of standard Shadow Mapping with Sub-Pixel Shadow Mapping (SPSM). On the lef... more Figure 1: Comparisons of standard Shadow Mapping with Sub-Pixel Shadow Mapping (SPSM). On the left, the YeahRight model (≈ 150 000 polys) using a 1K × 1K shadow map rendered in 11 ms with SPSM. On the right, a large City model (≈ 2 300 000 polys) rendered using a single 2K × 2K shadow map in 41.6 ms. SPSM brings sub-pixel accuracy to shadow maps, avoiding aliasing artifacts while preserving the rendering speed.
Proceedings of the 18th International Conference on 3D Web Technology, 2013
Figure 1: We introduce a novel event evaluation framework using task parallelism on multi/many-co... more Figure 1: We introduce a novel event evaluation framework using task parallelism on multi/many-core CPU architectures for real-time animation of complex scenes. Our framework supports 5 dynamic scheduling strategies based on OpenMP and custom Pthread-based approaches. Parallel evaluation timings for an animation frame on a 6-core CPU are displayed for the implemented custom Pthread-based (left) and OpenMP-based (right) static schedulers for a population of 1K humanoids generating 110K events per frame. Each rectangle corresponds to the evaluation of a single scene graph node (bones transformations and skeletal constraint evaluation at left and right figure parts respectively). The color of each consecutive rectangle is modified automatically for readability purpose. The gaps correspond to the time spent either in sequential execution or idle.
Figure 1: Production-quality clouds (600 × 400 × 300) rendered at 45 fps. Our solution gathers lo... more Figure 1: Production-quality clouds (600 × 400 × 300) rendered at 45 fps. Our solution gathers local extinction for a simple formulation of light transmission in heterogeneous media. We provide high quality results while remaining independent from the volume representation. The interaction between light and participating media involves complex physical phenomena such as light absorption and scattering. The radiance transmitted through a medium then depends on the variations of scattering and extinction along potentially complex light paths, yielding soft light shafts and shadowing (Figure 1). Computing light scattering in these media usually requires complex offline computations [Cerezo et al. 2005]. Some real-time applications are based on heavy precomputations [Zhou et al. 2008]. Some others introduce restrictions such as approximate diffusion schemes, or specific volume representations.
Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly ha... more Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right.
IEEE Transactions on Visualization and Computer Graphics, 2005
In this paper, we present a ray tracing-based method for accelerated global illumination computat... more In this paper, we present a ray tracing-based method for accelerated global illumination computation in scenes with lowfrequency glossy BRDFs. The method is based on sparse sampling, caching, and interpolating radiance on glossy surfaces. In particular, we extend the irradiance caching scheme proposed by Ward et al. [1] to cache and interpolate directional incoming radiance instead of irradiance. The incoming radiance at a point is represented by a vector of coefficients with respect to a hemispherical or spherical basis. The surfaces suitable for interpolation are selected automatically according to the roughness of their BRDF. We also propose a novel method for computing translational radiance gradient at a point.
We present a method for fast volume rendering using graphics hardware (GPU). To our knowledge, it... more We present a method for fast volume rendering using graphics hardware (GPU). To our knowledge, it is the first implementation on the GPU. Based on the Shear-Warp algorithm, our GPU-based method provides real-time frame rates and outperforms the CPU-based implementation. When the number of slices is not sufficient, we add in-between slices computed by interpolation. This improves then the quality of the rendered images. We have also implemented the ray marching algorithm on the GPU. The results generated by the three algorithms (CPU-based and GPU-based Shear- Warp, GPU-based Ray Marching) for two test models has proved that the ray marching algorithm outperforms the shear-warp methods in terms of speed up and image quality.
We extend GPU shape grammars [MBG∗12] to model highly detailed roofs. Starting from a consistent ... more We extend GPU shape grammars [MBG∗12] to model highly detailed roofs. Starting from a consistent roof structure such as a straight skeleton computed from the building footprints, we decompose this information into local roof parameters per input segments compliant with GPU shape grammars. We also introduce Join and Project rules for a consistent description of roofs using grammars, bringing the massive parallelism of GPU shape grammars to the benefit of coherent generation of global structures.
Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly ha... more Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right.
L'oeil humain, organe important dans le processus de la communication non verbale, ncessite une m... more L'oeil humain, organe important dans le processus de la communication non verbale, ncessite une modlisation anatomiquement correcte ainsi que des mthodes de rendu raliste; ce afin d'accrotre le ralisme des personnages virtuels. Les rcentes amliorations matrielles permettent dsormais le rendu de matriaux organiques complexes, tenant compte de critres anatomiques. Nous proposons une nouvelle mthode de modlisation de l'iris humain permettant de reconstruire la structure interne de celui-ci et de retrouver ses paramtres de diffusion partir d'une photographie d'oeil. Ainsi, nous prsentons une mthode de drefraction d'image d'iris. Nous modlisons l'iris suivant la representation du Subsurface Texture Mapping [1] qui permet de dcrire les variations d'paisseurs des diffrentes couches de l'iris. Nous proposons enfin une mthode de rendu raliste et temps rel de l'oeil humain en introduisant une fonction de rfraction qui permet de tenir compte de la rfraction de la lumire l'interface air/corne.
Fast global illumination computation is a challenge in several fields such as lighting simulation... more Fast global illumination computation is a challenge in several fields such as lighting simulation and computergenerated visual effects for movies. To this end, the irradiance caching algorithm is commonly used since it provides high-quality rendering in a reasonable time. However this algorithm relies on a spatial data structure in which nearest-neighbors queries and data insertions are performed alternately within a single rendering step. Due to this central and permanently modified data structure, the irradiance caching algorithm cannot be easily implemented on graphics hardware. This paper proposes a novel approach to global illumination using irradiance and radiance cache: the radiance cache splatting. This method directly meets the processing constraints of graphics hardware since it avoids the need of complex data structure and algorithms. Moreover, the rendering quality remains identical to classical irradiance and radiance caching. Our renderer shows an implementation of our algorithm which provides a significant speedup compared to classical irradiance caching.
Proceedings of the 16th International Conference on 3D Web Technology - Web3D '11, 2011
Figure 1: Our approach for adaptive streaming at multiple levels: planet-scale structuration, vis... more Figure 1: Our approach for adaptive streaming at multiple levels: planet-scale structuration, visibility-based occlusion culling, multiresolution meshes and textures, and adaptive reconstruction of procedural models.
Proceedings of the 3rd international conference on Computer graphics and interactive techniques in Australasia and South East Asia, 2005
We describe a generic solution for remote adaptive streaming and rendering of large terrains. The... more We describe a generic solution for remote adaptive streaming and rendering of large terrains. The challenge is to ensure a fast rendering and a rapidly improving quality with any user interaction, network capacity and rendering system performance. We adapt to these constraints so loading and rendering speeds do not depend on the size of the database. We can thus use any database with any client device. Our solution relies on a generic data structure to adaptively handle data from the server hard disk to the client rendering system. The same methods apply whatever is done with these data: only the data themselves and the rendering system vary. We base our data structure on existing solutions with good properties and add new methods to handle it more efficiently. In particular we avoid loading irrelevant or redundant data and we request the most important data first. We also avoid costly data structure operations as much as possible, in favor of "in-place" data updates and selection using sample masks.
Proceedings of the Digital Production Symposium on - DigiPro '12, 2012
Figure 1: Scenes from Wrath of the Titans (a) and Prometheus (b) involve extremely dense volumetr... more Figure 1: Scenes from Wrath of the Titans (a) and Prometheus (b) involve extremely dense volumetric objects. We adapt the Transmittance Function Mapping algorithm for high quality interactive previsualization and tuning of those media. Images: (a)
Figure 1: Comparisons of standard Shadow Mapping with Sub-Pixel Shadow Mapping (SPSM). On the lef... more Figure 1: Comparisons of standard Shadow Mapping with Sub-Pixel Shadow Mapping (SPSM). On the left, the YeahRight model (≈ 150 000 polys) using a 1K × 1K shadow map rendered in 11 ms with SPSM. On the right, a large City model (≈ 2 300 000 polys) rendered using a single 2K × 2K shadow map in 41.6 ms. SPSM brings sub-pixel accuracy to shadow maps, avoiding aliasing artifacts while preserving the rendering speed.
Proceedings of the 18th International Conference on 3D Web Technology, 2013
Figure 1: We introduce a novel event evaluation framework using task parallelism on multi/many-co... more Figure 1: We introduce a novel event evaluation framework using task parallelism on multi/many-core CPU architectures for real-time animation of complex scenes. Our framework supports 5 dynamic scheduling strategies based on OpenMP and custom Pthread-based approaches. Parallel evaluation timings for an animation frame on a 6-core CPU are displayed for the implemented custom Pthread-based (left) and OpenMP-based (right) static schedulers for a population of 1K humanoids generating 110K events per frame. Each rectangle corresponds to the evaluation of a single scene graph node (bones transformations and skeletal constraint evaluation at left and right figure parts respectively). The color of each consecutive rectangle is modified automatically for readability purpose. The gaps correspond to the time spent either in sequential execution or idle.
Figure 1: Production-quality clouds (600 × 400 × 300) rendered at 45 fps. Our solution gathers lo... more Figure 1: Production-quality clouds (600 × 400 × 300) rendered at 45 fps. Our solution gathers local extinction for a simple formulation of light transmission in heterogeneous media. We provide high quality results while remaining independent from the volume representation. The interaction between light and participating media involves complex physical phenomena such as light absorption and scattering. The radiance transmitted through a medium then depends on the variations of scattering and extinction along potentially complex light paths, yielding soft light shafts and shadowing (Figure 1). Computing light scattering in these media usually requires complex offline computations [Cerezo et al. 2005]. Some real-time applications are based on heavy precomputations [Zhou et al. 2008]. Some others introduce restrictions such as approximate diffusion schemes, or specific volume representations.
Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly ha... more Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right.
IEEE Transactions on Visualization and Computer Graphics, 2005
In this paper, we present a ray tracing-based method for accelerated global illumination computat... more In this paper, we present a ray tracing-based method for accelerated global illumination computation in scenes with lowfrequency glossy BRDFs. The method is based on sparse sampling, caching, and interpolating radiance on glossy surfaces. In particular, we extend the irradiance caching scheme proposed by Ward et al. [1] to cache and interpolate directional incoming radiance instead of irradiance. The incoming radiance at a point is represented by a vector of coefficients with respect to a hemispherical or spherical basis. The surfaces suitable for interpolation are selected automatically according to the roughness of their BRDF. We also propose a novel method for computing translational radiance gradient at a point.
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Papers by Pascal Gautron