TECHNIQUE FOR PRE-COMPUTING AMBIENT OBSCURANCE

• US 20150187129A1
• Filed: 01/02/2014
• Published: 07/02/2015
• Est. Priority Date: 01/02/2014
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: SLOAN, Peter-Pike Johannes
• Granted Patent: US 9,569,885 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 1/60 Memory management
• CPC Class Codes: G06T 15/60 Shadow generation

Abstract

One embodiment of the present invention includes techniques for pre-computing ambient shadowing parameters for a computer-generated scene. A processing unit retrieves a reference object associated with the computer-generated scene and comprising a plurality of vertices. For each vertex in the plurality of vertices, the processing unit computes a local ambient shadowing parameter, and stores the local ambient shadowing parameter in a memory. For each instance of the reference object included in the computer-generated scene, the processing unit computes a first global ambient shadowing parameter based on the position of the instance within the computer-generated scene, and stores the first global ambient shadowing parameter in the memory. One advantage of the disclosed embodiments is that ambient obscurance is applied to instance objects in a scene in real time while reducing memory space dedicated to storing the AO parameters.

Claims

1. A method for pre-computing ambient shadowing parameters for a computer-generated scene, the method comprising:

retrieving a reference object associated with the computer-generated scene and comprising a plurality of vertices;

for each vertex in the plurality of vertices;

computing a local ambient shadowing parameter, and

storing the local ambient shadowing parameter in a memory; and

for each instance of the reference object included in the computer-generated scene;

computing a first global ambient shadowing parameter based on the position of the instance within the computer-generated scene, and

storing the first global ambient shadowing parameter in the memory.

2. The method of claim 1, further comprising for each vertex of a first instance of the reference object, computing a composite ambient shadowing parameter based on the local shadowing parameter and the first global shadowing parameter.

3. The method of claim 1, wherein for each instance of the reference object included in the computer-generated scene, the first global shadowing parameter is based on a distance from the instance to a respective nearest occluding object.

4. The method of claim 1, further comprising:

for each instance of the reference object included in the computer-generated scene;

determining that a size associated with the instance exceeds a threshold value,

computing a second global ambient shadowing parameter based on the position of the instance within the computer-generated scene,

computing a third global ambient shadowing parameter based on the position of the instance within the computer-generated scene,

computing a fourth global ambient shadowing parameter based on the position of the instance within the computer-generated scene, and

storing the second global ambient shadowing parameter, the third global ambient shadowing parameter, and the fourth global ambient shadowing parameter in the memory.

5. The method of claim 1, wherein computing the first global ambient shadowing parameter comprises evaluating the first global shadowing parameter at a first distance between a light source and the instance of reference object, and further comprising:

for each instance of the reference object included in the computer-generated scene;

computing a second global ambient shadowing parameter based on the position of the instance within the computer-generated scene, comprising evaluating the second global shadowing parameter at a second distance between the light source and the instance of reference object, and

storing the second global ambient shadowing parameter in the memory.

6. The method of claim 5, further comprising computing a composite ambient shadowing parameter based on the local ambient shadowing parameter, the first global ambient shadowing parameter, and the second global ambient shadowing parameter.

7. The method of claim 1, wherein for each vertex in the plurality of vertices, the local ambient shadowing parameter is based on a square of a difference between an input ambient obscurance signal and the local ambient shadowing parameter.

8. The method of claim 1, wherein for each vertex in the plurality of vertices, the local ambient shadowing parameter is based on a weighted edge-based regularizer term.

9. A computer-readable storage medium including instructions that, when executed by a processing unit, cause the processing unit to perform an operation for pre-computing ambient shadowing parameters for a computer-generated scene, the operation comprising:

retrieving a reference object associated with the computer-generated scene and comprising a plurality of vertices;

for each vertex in the plurality of vertices;

computing a local ambient shadowing parameter, and

storing the local ambient shadowing parameter in a memory; and

for each instance of the reference object included in the computer-generated scene;

computing a first global ambient shadowing parameter based on the position of the instance within the computer-generated scene, and

storing the first global ambient shadowing parameter in the memory.

10. The computer-readable storage medium of claim 9, wherein the operation further comprises for each vertex of a first instance of the reference object, computing a composite ambient shadowing parameter based on the local ambient shadowing parameter and the first global ambient shadowing parameter.

11. The computer-readable storage medium of claim 9, wherein for each instance of the reference object included in the computer-generated scene, the first global shadowing parameter is based on a distance from the instance to a respective nearest occluding object.

12. The computer-readable storage medium of claim 9, wherein the operation further comprises:

for each instance of the reference object included in the computer-generated scene;

determining that a size associated with the instance exceeds a threshold value,

computing a second global ambient shadowing parameter based on the position of the instance within the computer-generated scene,

computing a third global ambient shadowing parameter based on the position of the instance within the computer-generated scene,

computing a fourth global ambient shadowing parameter based on the position of the instance within the computer-generated scene, and

storing the second global ambient shadowing parameter, the third global ambient shadowing parameter, and the fourth global ambient shadowing parameter in the memory.

13. The computer-readable storage medium of claim 9, wherein computing the first global ambient shadowing parameter comprises evaluating the first global shadowing parameter at a first distance between a light source and the instance of reference object, and further comprising:

for each instance of the reference object included in the computer-generated scene;

computing a second global ambient shadowing parameter based on the position of the instance within the computer-generated scene, comprising evaluating the second global shadowing parameter at a second distance between the light source and the instance of reference object, and

storing the second global ambient shadowing parameter in the memory.

14. The computer-readable storage medium of claim 13, wherein the operation further comprises computing a composite ambient shadowing parameter based on the local ambient shadowing parameter, the first global ambient shadowing parameter, and the second global ambient shadowing parameter.

15. The computer-readable storage medium of claim 9, wherein for each vertex in the plurality of vertices, the local ambient shadowing parameter is based on a square of a difference between an input ambient obscurance signal and the local ambient shadowing parameter.

16. The computer-readable storage medium of claim 9, wherein for each vertex in the plurality of vertices, the local ambient shadowing parameter is based on a weighted edge-based regularizer term.

18. The computer-readable storage medium of claim 16, wherein for each visibility region included within the computer-generated scene, computing the region ambient shadowing parameter comprises:

generating a plurality of sample points, wherein each sample point in the plurality of sample points intersects with the dynamic object, and

selecting a subset of sample points from the plurality of sample points, wherein each sample point in the subset of sample points is visible to less than a threshold quantity of back-facing objects.

20. The computer-readable storage medium of claim 16, wherein for each visibility region included within the computer-generated scene, computing the region ambient shadowing parameter comprises evaluating the region ambient shadowing parameter at a first point representing a geometric center of the visibility region.

17. A computer-readable storage medium including instructions that, when executed by a processing unit, cause the processing unit to perform an operation for pre-computing ambient shadowing parameters for a computer-generated scene, the operation comprising:

for each visibility region included within the computer-generated scene;

computing a region ambient shadowing parameter based on a dynamic object associated with the computer-generated scene,

modifying the region ambient shadowing parameter based on a corresponding region ambient shadowing parameter from a neighboring visibility region to generate a first modified region ambient shadowing parameter, and

modifying the first modified region ambient shadowing parameter based on a region ambient shadowing parameter from a different frame of the computer-generated scene to generate a second modified region ambient shadowing parameter, and

storing the second modified region ambient shadowing parameter in the memory.

19. The computer-readable storage medium of claim 17, wherein for each visibility region included within the computer-generated scene, computing the region ambient shadowing parameter further comprises evaluating the region ambient shadowing parameter at a first point representing a center of mass of the sample points in the subset of sample points.