Microfacet surface rendering
A technique for rendering is provided. The technique includes obtaining one or more samples for a pixel, the samples obtained for a microfacet surface from a spherical cap cut off by a lower plane positioned to exclude reflected rays that are occluded by the microfacet surface; obtaining one or more contributions corresponding to the one or more samples; determining a color for the pixel based on the one or more contributions.
1 . A method for rendering, the method comprising:
obtaining one or more samples for a pixel, the samples obtained for a microfacet surface from a spherical cap cut off by a lower plane positioned to exclude reflected rays that are occluded by the microfacet surface and reflected rays that are beyond a horizon of a microfacet bump of the microfacet surface;
obtaining one or more contributions corresponding to the one or more samples; and
determining a color for the pixel based on the one or more contributions.
2 . The method of claim 1 , wherein roughness for the microfacet surface is isotropic and the lower plane is positioned based on a roughness parameter corresponding to the roughness.
3 . The method of claim 1 , wherein the lower plane is a distance from a top of the spherical cap, where the top is in a direction of a normal of a base surface of the microfacet surface.
4 . The method of claim 3 , wherein the distance is based on a roughness parameter for the microfacet surface.
5 . The method of claim 4 , wherein the distance is also based on a direction of an incoming ray.
6 . The method of claim 1 , wherein the one or more samples comprise one or more reflected directions.
7 . The method of claim 1 , wherein a z component of an incoming direction is below an origin of the spherical cap and the lower plane position is not based on roughness of the microfacet surface.
8 . The method of claim 1 , wherein the sampling includes selecting a point from an included portion of a spherical cap.
9 . The method of claim 1 , wherein the determining the color comprises combining the one or more contributions.
10 . A system for rendering, the system comprising:
a memory configured to store data for a pixel; and
a processor configured to
obtain one or more samples for the pixel, the samples obtained for a microfacet surface from a spherical cap cut off by a lower plane positioned to exclude reflected rays that are occluded by the microfacet surface and reflected rays that are beyond a horizon of a microfacet bump of the microfacet surface;
obtain one or more contributions corresponding to the one or more samples; and
determine a color for the pixel based on the one or more contributions.
11 . The system of claim 10 , wherein roughness for the microfacet surface is isotropic and the lower plane is positioned based on a roughness parameter corresponding to the roughness.
12 . The system of claim 10 , wherein the lower plane is a distance from a top of the spherical cap, where the top is in a direction of a normal of a base surface of the microfacet surface.
13 . The system of claim 12 , wherein the distance is based on a roughness parameter for the microfacet surface.
14 . The system of claim 13 , wherein the distance is also based on a direction of an incoming ray.
15 . The system of claim 10 , wherein the one or more samples comprise one or more reflected directions.
16 . The system of claim 10 , wherein a z component of an incoming direction is below an origin of the spherical cap and the lower plane position is not based on roughness of the microfacet surface.
17 . The system of claim 10 , wherein the sampling includes selecting a point from an included portion of a spherical cap.
18 . The system of claim 10 , wherein the determining the color comprises combining the one or more contributions.
19 . A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform operations comprising:
obtaining one or more samples for a pixel, the samples obtained for a microfacet surface from a spherical cap cut off by a lower plane positioned to exclude reflected rays that are occluded by the microfacet surface and reflected rays that are beyond a horizon of a microfacet bump of the microfacet surface;
obtaining one or more contributions corresponding to the one or more samples; and
determining a color for the pixel based on the one or more contributions.
20 . The non-transitory computer-readable medium of claim 19 , wherein roughness for the microfacet surface is isotropic and the lower plane is positioned based on a roughness parameter corresponding to the roughness.