US 9,070,208 B2Granted

Accelerated subsurface scattering determination for rendering 3D objects

AssigneeLucasfilm Entertainment Company Ltd.

InventorsCharlie A. Kilpatrick, Clifford Ramshaw

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Abstract

The present disclosure includes, among other things, systems, methods, and program products for estimating radiant exitance due to subsurface scattering. For example, one or more aspects of the subject matter described in this disclosure can be embodied in one or more methods that include distributing a plurality of sample points across the surface of a 3D object model to be rendered into a 2D image and determining a solid angle subtended by a first sample point and a second sample point relative to a region on the 3D object model. Depending on the determined solid angle relative to a threshold value, a previously determined subsurface scattering contribution for the region or a newly determined subsurface scattering contribution for the region may selectively be used for rendering a portion of the 2D image.

Claims39

Dependent claims

A method performed by one or more processes executing on a computer system, the method comprising:

distributing a plurality of sample points across the surface of a three-dimensional (3D) object model to be rendered into a portion of a two-dimensional (2D) image;
constructing a hierarchical data structure based on a first subset of the plurality of sample points, the hierarchical data structure comprising a plurality of nodes wherein:
one node is a root node;
each leaf node is associated with a pre-pass shading sample;
and
each non-leaf node is associated with a cluster of pre-pass shading samples;
and
determining a total radiant exitance for a final pass shading sample under evaluation (FPSS-UE) based on the hierarchical data structure by at least:
recursively traversing the nodes of the hierarchical data structure starting at the root node;
at a particular node within the traversal, determining a first solid angle, measured with respect to a position associated with the particular node, between a position associated with the FPSS-UE and a position associated with a final pass shading sample stored (FPSS-S) with the particular node for which a subsurface scattering contribution has been previously determined;
determining a first threshold value in part by applying a luminosity function to an incident irradiance associated with the particular node;
and
depending on the determined first solid angle relative to the first threshold value, selectively either:
(1) when the first solid angle is less than the first threshold value, adding the previously determined subsurface scattering contribution stored with the particular node to the total radiant exitance for the FPSS-U, or (2) when the first solid angle is greater than or equal to the first threshold value, estimating a newly determined subsurface scattering contribution corresponding to the particular node, storing the newly determined subsurface scattering contribution corresponding to the particular node in association with the hierarchical data structure, and adding the newly determined subsurface scattering contribution to the total radiant exitance for the FPSS-UE.

11 more elements

A computer program product, encoded on a non-transitory computer-readable medium, operable to cause a data processing apparatus to perform operations comprising:

distributing a plurality of sample points across the surface of a three-dimensional (3D) object model to be rendered into a portion of a two-dimensional (2D) image;
constructing a hierarchical data structure based on a first subset of the plurality of sample points, the hierarchical data structure comprising a plurality of nodes wherein:
one node is a root node;
each leaf node is associated with a pre-pass shading sample;
and
each non-leaf node is associated with a cluster of pre-pass shading samples;
and
determining a total radiant exitance for a final pass shading sample under evaluation (FPSS-UE) based on the hierarchical data structure by at least:
recursively traversing the nodes of the hierarchical data structure starting at the root node;
at a particular node within the traversal, determining a first solid angle, measured with respect to a position associated with the particular node, between a position associated with the FPSS-UE and a position associated with a final pass shading sample stored (FPSS-S) with the particular node for which a subsurface scattering contribution has been previously determined;
determining a first threshold value in part by applying a luminosity function to an incident irradiance associated with the particular node;
and
depending on the determined first solid angle relative to the first threshold value, selectively either:
(1) when the first solid angle is less than the first threshold value, adding the previously determined subsurface scattering contribution stored with the particular node to the total radiant exitance for the FPSS-UE, or (2) when the first solid angle is greater than or equal to the first threshold value, estimating a newly determined subsurface scattering contribution corresponding to the particular node, storing the newly determined subsurface scattering contribution corresponding to the particular node in association-with the hierarchical data structure, and adding the newly determined subsurface scattering contribution to the total radiant exitance for the FPSS-UE.

11 more elements

A system comprising:

a processor:
and
a computer program product encoded on a non-transitory computer-readable medium, the computer program product configured to cause the processor to perform the operations comprising:
distributing a plurality of sample points across the surface of a three-dimensional (3D) object model to be rendered into a portion of a two-dimensional (2D) image;
constructing a hierarchical data structure over a first subset of the plurality of sample points, the hierarchical data structure comprising a plurality of nodes wherein:
one node is a root node;
each leaf node is associated with a pre-pass shading sample;
and
each non-leaf node is associated with a cluster of pre-pass shading samples;
and
determining a total radiant exitance for a final pass shading sample under evaluation (FPSS-UE) based on the hierarchical data structure by at least:
recursively traversing the nodes of the hierarchical data structure starting at the root node;
at a particular node within the traversal, determining a first solid angle, measured with respect to a position associated with the particular node, between a position associated with the FPSS-UE and a position associated with a final pass shading sample stored (FPSS-S) with the particular node for which a subsurface scattering contribution has been previously determined;
determining a first threshold value in part by applying a luminosity function to an incident irradiance associated with the particular node;
and
depending on the determined first solid angle relative to the first threshold value, selectively either:
(1) when the first solid angle is less than the first threshold value, adding the previously determined subsurface scattering contribution stored with the particular node to the total radiant exitance for the FPSS-UE, or (2) when the first solid angle is greater than or equal to the first threshold value, estimating a newly determined subsurface scattering contribution corresponding to the particular node, storing the newly determined subsurface scattering contribution corresponding to the particular node in association with the hierarchical data structure, and adding the newly determined subsurface scattering contribution to the total radiant exitance for the FPSS-U E.

14 more elements

A method performed by one or more processes executing on a computer system, the method comprising:

distributing a plurality of sample points across the surface of a three-dimensional (3D) object model to be rendered into a portion of a two-dimensional (2D) image;
constructing a hierarchical octree data structure based on a first subset of the plurality of sample points, the octree data structure comprising a plurality of nodes wherein:
one node is a root node;
each node in the octree is associated with at least one of the sample points in the first subset;
each leaf node comprises a pre-pass shading sample;
each non-leaf node comprises a cluster of pre-pass shading samples;
and
a non-leaf node in the octree represents a region on the 3D object, wherein the non-leaf node representing the region includes a previously determined subsurface scattering contribution and a position of a first sample point used in the determination of the previously determined subsurface scattering contribution, the first sample point being from a second subset of the plurality of sample points;
and
determining a total radiant exitance for a final pass shading sample under evaluation (FPSS-UE) based on the hierarchical data structure by at least:
recursively traversing the nodes of the hierarchical octree data structure starting at the root node;
at a particular node within the transversal, determining a first solid angle, measured with respect to a position associated with the particular node, between a position associated with the FPSS-UE and a position associated with a final pass shading sample stored (FPSS-S) with the particular node for which a subsurface scattering contribution has been previously determined;
determining a first threshold value in part by applying a luminosity function to an incident irradiance associated with the region;
depending on the determined first solid angle relative to the first threshold value, selectively either:
(1) when the first solid angle is less than the first threshold value, adding the previously determined subsurface scattering contribution to the total radiant exitance for the FPSS-UE, or (2) when the first solid angle is greater than or equal to the first threshold value, estimating a newly determined subsurface scattering contribution corresponding to the particular node, storing the newly determined subsurface scattering contribution corresponding to the particular node in association with the hierarchical data structure, and adding the newly determined subsurface scattering contribution to the total radiant exitance for the FPSS-UE.

12 more elements

Dependencies are inferred from the claim text.