Line space gathering for single scattering in large scenes

• US 8,922,556 B2
• Filed: 04/18/2011
• Issued: 12/30/2014
• Est. Priority Date: 04/18/2011
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lin, Stephen S., Guo, Baining, Xin, Sun
• Primary Examiner(s): Yang, Ryan R
• Assistant Examiner(s): BADER, ROBERT N.
• Application Number:
  US13/089,122
• Publication Number:
  US 20120262456A1
• Time in Patent Office: 1,352 Days
• Field of Search: None
• US Class Current: 345/426
• CPC Class Codes: G06T 15/06 Ray-tracing
• CPC Class Codes: G06T 15/506 Illumination models

Abstract

A light gathering process may reduce the computational resources and storage required to render a scene with a participating homogeneous media. According to some implementations, Efficiency may be obtained by evaluating the final radiance along a viewing ray directly from the lighting rays passing near to it, and by rapidly identifying such lighting rays in the scene. To facilitate a search for nearby lighting rays, the lighting rays and viewing rays may be represented as a 6D point and a plane according to the corresponding Plucker coordinates and coefficients, respectively.

Claims

1. A computer-implemented method for light gathering in a homogeneous media, the method comprising:

without photon representation, using a light ray gathering module to trace (i) one or more lighting rays emitted from a light source and (ii) one or more viewing rays emitted from view source in a first space;

representing each lighting ray as a Plü

cker coordinate in a second space;

representing each viewing ray as a Plü

cker coefficient describing a hyper plane in the second space;

determining the distance between at least one of the Plü

cker coordinates and at least one of the corresponding Plü

cker coefficients in the second space, such that the distance determined in the second space is related to the distance of the corresponding lighting ray and viewing ray in the first space;

computing (i) initial flux of the one or more lighting rays in the second space and (ii) initial transmittance to the view source of the one or more viewing rays in the second space; and

evaluating a final radiance along the viewing ray based upon a lighting ray passing nearest to the viewing ray.

2. The computer-implemented method of claim 1, wherein the one or more lighting rays and the one or more viewing rays are reflected and refracted multiple times.

3. The computer-implemented method of claim 1, wherein the determining the distance between the at least one Plü

cker coordinate and the at least one Plü

cker coefficient comprises searching for one or more lighting rays nearest to a viewing ray.

4. The computer-implemented method of claim 1 further comprising utilizing the hyper plane described by a Plü

cker coefficient to query one or more Plü

cker coordinates established by the one or more corresponding lighting rays.

5. The computer-implemented method of claim 4, wherein for each point gathered by a hyper plane query there is a corresponding intersection point between a lighting ray and a viewing ray.

6. The computer-implemented method of claim 1 further comprising depositing the final radiance of a viewing ray to a corresponding pixel of a scene to generate a final image.

7. A system comprising:

a memory;

one or more processors coupled to the memory; and

a line gathering module operable on the one or more processors, the line gathering module configured to;

without photon representation, represent a lighting ray as a coordinate and a viewing ray as a coefficient in a 6D parametric line space;

compute (i) initial flux of the lighting ray in the 6D parametric line space and (ii) initial transmittance to a view source of the viewing ray in the 6D parametric line space; and

construct a spatial hierarchy using the coefficient and the coordinate, the spatial hierarchy configured to perform a search comprising a plane query within a given set of points.

8. The system of claim 7, wherein the constructing the spatial hierarchy enables an accelerated search for the first ray which lies nearest to each identified second ray.

9. The system of claim 7, wherein the first ray is represented as a Plü

cker coordinate in the 6D parametric line space.

10. The system of claim 9, wherein the second ray is represented as a Plü

cker coefficient defining a 6D hyper plane in the 6D parametric line space.

11. The system of claim 10, wherein the 6D hyper plane is utilized to query the Plü

cker coordinate in the spatial hierarchy.

12. The system of claim 7, wherein a lighting ray closest to a viewing ray may be determined using the constructed spatial hierarchy, the spatial hierarchy comprising a point π

(I) in the 6D parametric line space.

13. One or more computer storage devices storing computer-executable instructions that, when executed on one or more processors, cause the one or more processors to perform operations comprising:

without photon representation, gathering light rays to render a single scattering with a homogeneous media;

facilitating a search within a scene of the homogeneous media to identify a lighting ray passing nearest to a recognized viewing ray;

representing the identified lighting ray as a Plü

cker coordinate in a 6D space;

representing the recognized viewing ray as a Plü

cker coefficient in a 6D space;

computing (i) initial flux of the identified lighting ray in the 6D space and (ii) initial transmittance to a view source of the recognized viewing ray in the 6D space; and

evaluating a final radiance along the recognized viewing ray based upon the identified lighting ray passing nearest to the recognized viewing ray.

14. The one or more computer storage devices of claim 13, wherein the Plü

cker coefficient defines a hyper plane passing through an origin in the 6D space.

15. The one or more computer storage devices of claim 14, wherein the hyper plane is employed to query the Plü

cker coordinate in a spatial hierarchy to facilitate the search.

16. The one or more computer storage devices of claim 13, further comprising locating an intersection point between the identified lighting ray and the recognized viewing ray in 3D space, the intersection point determined based upon a distance between the lighting ray and the viewing ray detected in 6D space.

17. The one or more computer storage devices of claim 13, wherein the final radiance transfer is deposited to a corresponding pixel of the scene to generate a final image.