Reflection space image based rendering

Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension

Reexamination Certificate

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C345S420000, C345S426000, C345S427000, C345S582000, C345S581000, C345S424000, C345S646000, C345S645000

Reexamination Certificate

active

06697062

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of computer graphics.
2. Related Art
Offline rendering algorithms have to a great extent conquered physically accurate photo-realism and complex synthetic shading. A result of over twenty years of research, these techniques all solve the lighting or rendering equation in some manner. See, the techniques in Blinn, J. F. and Newell, M. E.,
Comm. ACM
19:542-546 (1976); Cook, R. L., et al., “The Reyes image rendering architecture,” in
Computer Graphics
(
SIGGRAPH
'87
Proc
.), vol. 21, Stone, M. C., ed., (July 1987), pp. 95-102; Debevec, P., “Rendering synthetic objects into real scenes: Bridging traditional and image-based graphics with global illumination and high dynamic range photography,” in
SIGGRAPH
98
Conf. Proc
., Cohen, M., ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley (July 1998), pp. 189-198; He, X. D., et al., “A comprehensive physical model for light reflection,” in
Computer Graphics
(
SIGGRAPH
'91
Proc
.), vol. 25, Sederberg, T. W., ed. (July 1991), pp. 175-186; Jensen, H. W. and Christensen, P. H., “Efficient simulation of light transport in scenes with participating media using photon maps,” in
SIGGRAPH
98
Conf. Proc
., Cohen, M., ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley (July 1998), pp. 311-320; Miller, G. S. and Hoffinan, C. R., “Illumination and reflection maps: Simulated objects in simulated and real environments, in
SIGGRAPH
'84
Advanced Computer Graphics Animation seminar notes
(July 1994); Poulin, P. and Fournier, A., “A model for anisotropic reflection, ” in
Computer Graphics
(
SIGGRAPH
'90
Proc
.), vol. 24, Baskett, F., ed., (August 1990), pp. 273-284; Veach, E. and Guibas, L. J., “Metropolis light transport,” in
SIGGRAPH
97
Conf. Proc
., Whitter, T., ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley (August 1997), pp. 65-76, and the rendering equation in Kajiya, J. T., “The rendering equation,”
Computer Graphics
(SIGGRAPH '86
Proc
.), vol. 20, Evans, D. C. and Athay, R. J., eds., (August 1986), pp. 143-150.
A trade-off between speed and quality exists in off-line rendering and interactive rendering. The outstanding rendering challenge now becomes how to increase the performance of sophisticated shading algorithms without losing the advancements made in quality. This implies that many orders of magnitude in performance improvements must be found. Traditionally, this has been accomplished by vastly simplifying the approximations used in the shading and lighting equations—resulting in a significant loss in complexity and quality.
Environment mapping is one method used to improve the realism of interactive rendering. As originally described by Newell and Blinn (Blinn, J. F. and Newell, M. E.,
Comm. ACM
19:542-546 (1976)), a simple environment map is used to quickly find reflections of distant objects from a perfectly mirrored surface. Other researchers refined this notion by generalizing the BRDF used, though some of these refinements lost the interactivity of simple environment mapping. See, Cabral, B., et al., “Bidirectional reflection functions from surface bump maps,” in
Computer Graphics
(
SIGGRAPH
'87
Proc
.), vol. 21, Stone, M. C., ed., (July 1987), pp. 273-281; Greene, N., “Applications of world projections,” in Proc.
Graphics Interface
'86, Green, M., ed. (May 1986), pp. 108-114; Miller, G. S. and Hoffman, C. R., “Illumination and reflection maps:
Simulated objects in simulated and real environments, in
SIGGRAPH
'84
Advanced Computer Graphics Animation seminar notes
(July 1994); Poulin, P. and Fournier, A., “A model for anisotropic reflection, ” in
Computer Graphics
(
SIGGRAPH
'90
Proc.), vol.
24, Baskett, F., ed., (August 1990), pp. 273-284.
Another method used to bridge the gap between realism and interactivity is image based rendering (McMillan, L. and Bishop, G., “Plenoptic modeling: An image-based rendering system,” in
SIGGRAPH
95
Conf. Proc
., Cook, R., ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley (August 1995), pp. 39-46). Image based rendering (IBR) avoids solving the lighting equation during interactive rendering by warping existing photographs or images. These images can be thought of as radiance maps (Gershbein, R., et al., “Textures and radiosity: Controlling emission and reflection with texture maps,” in
Proc. SIGGRAPH
'94 (Orlando, Fla., Jul. 24-29, 1994), Glassner, A., ed., Computer Graphics Proceedings, Annual Conference Series, ACM SIGGRAPH, ACM Press (July 1994), pp. 51-58), and generalized to light fields (Levoy, M. and Hanrahan, P., “Light field rendering,” in
SIGGRAPH
96
Conf. Proc
., Rushmeier, H., ed., Annual Conference Series, ACM SIGGRAPH, ACM Press (August 1996), pp. 31-42) and lumigraphs (Gortler, S. J., et al., “The lumigraph,” in
SIGGRAPH
96
Conf. Proc
., Rushmeier, H., ed., Annual Conference Series, ACM SIGGRAPH, ACM Press (August 1996), pp. 43-54). This works well for predefined scenes or images, but not for dynamically changing synthetic objects.
Recently, Debevec (Debevec, P., “Rendering synthetic objects into real scenes: Bridging traditional and image-based graphics with global illumination and high dynamic range photography,” in
SIGGRAPH
98
Conf. Proc
., Cohen, M., ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley (July 1998), pp. 189-198) combined captured environment maps and synthetic objects to produce compelling renderings with both synthetic objects and image based environments. His techniques do not work at interactive rates since he computes the lighting equation integration as he renders using RADIANCE (Ward, G. J., “The RADIANCE lighting simulation and rendering system,”
Proc. SIGGRAPH
'94 (Orlando, Fla., Jul. 24-29, 1994), Glassner, A., ed., Computer Graphics Proceedings, Annual Conference Series, ACM SIGGRAPH, ACM Press (July 1994), pp. 459-572).
What is needed is an interactive photo-realistic rendering algorithm or system.
SUMMARY OF THE INVENTION
The present invention provides a method, system, and computer program product for reflection space image based rendering of an object at an interactive frame rate. A set of source radiance environment maps associated with a set of source viewing vectors are warped to create a destination radiance environment map associated with a destination viewing vector in a current frame. Blending and weighting operations can also be applied in creating the final destination radiance environment map. An object is then rendered with texture environment mapping from the destination radiance environment map.
According to one embodiment, at set-up, geometry information for a global set of source viewing vectors and a global set of source radiance environment maps are loaded. A viewpoint tracking loop is then carried out for a current frame. In the viewpoint tracking loop, a destination viewing vector that points along a view direction of the current frame is determined. A subset of source viewing vectors is then determined from the previously loaded global set of source viewing vectors. In one preferred example, the subset of source viewing vectors are a number of viewing vectors (e.g., three source viewing vectors) closest to the destination viewing vector. A set of corresponding weights for the subset of source viewing vectors is also determined.
A warping and blending loop is then performed iteratively on each source radiance environment map corresponding to the subset of source viewing vectors. In one embodiment, each source radiance environment map is warped and blended per texel according to a warping function to a create a destination radiance environment map.
In another preferred embodiment, a fast approximation is made which avoids warping per texel over the entire source radiance environment map. A tessellated mesh with a set of warped texture coordinates is generated. For example, in the case where the source radiance environment maps are sphere maps, the tessellated mesh is simply a te

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