Visibility silhouettes for masked spherical integration

Patent metadata

Field	Value
Publication number	US-9501862-B2
Application number	US-201213692482-A
Country	US
Kind code	B2
Filing date	Dec 3, 2012
Priority date	Dec 3, 2012
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

The disclosure provides an approach for determining, in 3D rendering, the integrals of visibility-masked spherical functions using visibility silhouettes. For a given shade point, the visibility silhouette for that shade point includes a set of edges from the scene geometry which form the boundaries between visible and invisible regions of a hemisphere having the shade point as its center. For each shade point, a rendering application determines a set of contour edges of scene geometry, the contour edges being a superset of the set of visibility silhouette edges, by querying a 4D dual mesh. The rendering application then evaluates the integral of the visibility-masked spherical function for a given shade point by integrating over segments of discrete u-isolines for which an overlap function indicates that a ray from the shade point would not intersect scene geometry.

First claim

What is claimed is:

1. A computer-implemented method for rendering a 3D scene, comprising:
receiving, by a rendering application executing on a processor, geometry of the scene;
for each of a plurality of shade points in the scene:
determining a visibility silhouette by determining contour edges and by determining visibility silhouette edges from the contour edges, wherein the visibility silhouette edges define boundaries between visible and occluded regions from a perspective of the shade point and wherein the visibility silhouette edges are determined based on changes in value of an overlap function at intersections between the contour edges and u-isolines of a parameterization, wherein the contour edges are projected onto an octahedron, wherein the parameterization is of the octahedron, wherein the overlap function indicates whether geometry is intersected by a ray originating from the shade point, and wherein the u coordinate of the octahedral parameterization is the x coordinate of the octahedron equation |x|+|y|+|z|=1, and
determining a spherical visibility-masked integral, wherein spherical visibility in the integral is represented by the visibility silhouette; and
accelerating a rendering of the scene using, at least in part, one or more of the spherical visibility masked integrals of the shade points.

2. The method of claim 1 , wherein the contour edges are determined by:
determining boundary edges of the scene geometry; and
processing 4D line segment representations of respective non-boundary edges of the scene geometry into a bounding volume hierarchy and querying the bounding volume hierarchy for intersection with a 3D hyperplane normal to the shade point, wherein the 4D line segments have triangles adjacent to the respective edges as endpoints.

3. The method of claim 1 , wherein the u-isolines do not cross back from a half-space which is invisible from the perspective of the shade point if the u-isolines cross into the invisible half-space.

4. The method of claim 1 , wherein the integral is determined during one of glossy rendering, material editing, image relighting, all-frequency diffuse shading, and ambient occlusion computation.

5. A computer-implemented method for rendering a 3D scene, comprising:
receiving, by a rendering application executing on a processor, geometry of the scene;
for each of a plurality of shade points in the scene:
determining a visibility silhouette by determining contour edges and by determining visibility silhouette edges from the contour edges, wherein the visibility silhouette edges define boundaries between visible and occluded regions from a perspective of the shade point and wherein the visibility silhouette edges are determined based on changes in value of an overlap function at intersections between the contour edges and u-isolines of a parameterization, wherein the contour edges are projected onto a sphere, wherein the parameterization is of the sphere, and wherein the overlap function indicates whether geometry is intersected by a ray originating from the shade point, and
determining a spherical visibility-masked integral, wherein spherical visibility in the integral is represented by the visibility silhouette; and
accelerating a rendering of the scene using, at least in part, one or more of the spherical visibility masked integrals of the shade points.

6. The method of claim 5 , wherein the u-isolines do not cross back from a half-space which is invisible from the perspective of the shade point if the u-isolines cross into the invisible half-space.

7. The method of claim 5 , wherein determining the integral includes integrating a spherical function over segments of the u-isolines where the overlap function indicates the ray originating from the shade point does not intersect any scene geometry.

8. A non-transitory computer-readable storage medium storing instructions, which when executed on a processor, perform operations for rendering a 3D scene, comprising:
receiving, by a rendering application, geometry of the scene;
for each of a plurality of shade points in the scene:
determining a visibility silhouette by determining contour edges and by determining visibility silhouette edges from the contour edges, wherein the visibility silhouette edges define boundaries between visible and occluded regions from a perspective of the shade point and wherein the visibility silhouette edges are determined based on changes in value of an overlap function at intersections between the contour edges and u-isolines of a parameterization, wherein the contour edges are projected onto an octahedron, wherein the parameterization is of the octahedron, wherein the overlap function indicates whether geometry is intersected by a ray originating from the shade point, and wherein the u coordinate of the octahedral parameterization is the x coordinate of the octahedron equation |x|+|y|+|z|=1, and
determining a spherical visibility-masked integral, wherein spherical visibility in the integral is represented by the visibility silhouette; and
accelerating a rendering of the scene using, at least in part, one or more of the spherical visibility masked integrals of the shade points.

9. The computer-readable storage medium of claim 8 , wherein the contour edges are determined by:
determining boundary edges of the scene geometry; and
processing 4D line segment representations of respective non-boundary edges of the scene geometry into a bounding volume hierarchy and querying the bounding volume hierarchy for intersection with a 3D hyperplane normal to the shade point, wherein the 4D line segments have triangles adjacent to the respective edges as endpoints.

10. The computer-readable storage medium of claim 8 , wherein the u-isolines do not cross back from a half-space which is invisible from the perspective of the shade point if the u-isolines cross into the invisible half-space.

11. The computer-readable storage medium of claim 8 , wherein the integral is determined during one of glossy rendering, material editing, image relighting, all-frequency diffuse shading, and ambient occlusion computation.

12. A system, comprising:
a processor; and
a memory, wherein the memory includes an application program configured to perform operations for rendering a 3D scene, comprising:
receiving, by a rendering application, geometry of the scene;
for each of a plurality of shade points in the scene:
determining a visibility silhouette by determining contour edges and by determining visibility silhouette edges from the contour edges, wherein the visibility silhouette edges define boundaries between visible and occluded regions from a perspective of the shade point and wherein the visibility silhouette edges are determined based on changes in value of an overlap function at intersections between the contour edges and u-isolines of a parameterization, wherein the contour edges are projected onto an octahedron, wherein the parameterization is of the octahedron, wherein the overlap function indicates whether geometry is intersected by a ray originating from the shade point, and wherein the u coordinate of the octahedral parameterization is the x coordinate of the octahedron equation |x|+|y|+|z|=1, and
determining a spherical visibility-masked integral, wherein spherical visibility in the integral is represented by the visibility silhouette; and

accelerating a rendering of the scene using, at least in part, one or more of the spherical visibility masked integrals of the shade points.

Assignees

• Disney Entpr Inc

Inventors

• Nowrouzezahrai Derek
• Baran Ilya
• Mitchell Kenny
• Jarosz Wojciech

Classifications

• G06T15/40

  Hidden part removal · CPC title

• G06T15/06 Primary

  Ray-tracing · CPC title