System and method for artist friendly controls for hair shading
There is provided a system and method for artist friendly control of three-dimensional object shading, particularly hair. A methodology is disclosed for deriving a pseudo scattering function over a domain of Artist Friendly Controls (AFCs) from a physically based scattering function over a domain of Physically Based Controls (PBCs). The pseudo scattering function can provide intuitive decoupled adjustments of specific important visual characteristics while still providing a convincing and aesthetically pleasing result. An end user such as an artist may thus control the values, or AFCs, to implement specific aesthetic features for the shading of objects as seen on a display. The pseudo scattering function may be utilized for single scattering and multiple scattering models of hair shading.
1. A shading method for use by a computer system having a processor and a memory, the method comprising:
providing, using the processor, a user with control over separately defining values for each of the subcomponents of a light scattering by one or more fibers using a user interface, wherein each of the subcomponents controls a different visually apparent characteristic of the one or more fibers;
receiving, using the processor, from the user, the values of each of the subcomponents of the light scattering by the one or more fibers;
storing, using the processor, the values of each of the subcomponents in the memory;
combining, using the processor, the values of each of the subcomponents to determine pixel values for the one or more fibers; and
displaying, using the processor, the one or more fibers using the pixel values on a display;
wherein the one or more fibers are hair or fur fibers, and wherein the subcomponents of the light include:
a light that reflects off an outer surface of the one or more fibers (“R”);
a light that has transmitted through the one or more fibers (“TT”); and
a light that has been internally reflected off an inner surface of the one or more fibers (“TRT”).
2. The method of claim 1 , wherein the TRT is decomposed into two subcomponents including glints and the TRT excluding the glints.
3. The method of claim 1 , wherein properties of the one or more fibers include any of a color, an intensity, a longitudinal position and a longitudinal width, which is beyond a possible range of a physical based shader model applied to the one or more fibers.
4. The method of claim 1 , wherein displaying includes rendering a color, an intensity, a longitudinal position and a longitudinal width of the one or more fibers.
5. The method of claim 1 , wherein the user is provided with a direct control over defining the values.
6. The method of claim 1 further comprising:
providing, using the processor, the user with control over separately defining values for each of the subcomponents of the light scattering by a volume of fibers using the user interface, wherein each of the subcomponents of the light scattering by the volume of fibers controls a different visually apparent characteristic of the volume of fibers;
receiving, using the processor, from the user, the values of each of the subcomponents of the light scattering by the volume of fibers;
storing, using the processor, the values of each of the subcomponents of the light scattering by the volume of fibers in the memory;
combining, using the processor, the values of each of the subcomponents of the light scattering by the volume of fibers to determine pixel values of the volume of fibers; and
displaying, using the processor, the volume of fibers using the pixel values of the volume of fibers on a display;
wherein the volume of fibers is a volume of hair or fur fibers, and wherein the subcomponents of the light scattering by the volume of fibers include:
a light that scatters forward and maintains its forward directionality inside the volume of fibers (“FS”); and
a light that goes into the volume of fibers and comes back to a surface of the volume of fibers (“BS”).
7. The method of claim 6 , wherein properties of the volume of fibers include any of a color, an intensity, a longitudinal position and a longitudinal width, which is beyond a possible range of a physical based shader model applied to the volume of fibers.
8. The method of claim 6 , wherein displaying includes rendering a color, an intensity, a longitudinal position and a longitudinal width of the volume of fibers.
9. The method of claim 6 , wherein the user is provided with a direct control over defining the values for each of the subcomponents of the light scattering by the volume of fibers.
10. A computer system enabling a user to control a shading of one or more fibers on a display, the computer system comprising:
a memory; and
a processor configured to:
provide the user with control over separately defining values for each of the subcomponents of a light scattering by the one or more fibers using a user interface, wherein each of the subcomponents controls a different visually apparent characteristic of the one or more fibers;
receive, from the user, the values of each of the subcomponents of the light scattering by the one or more fibers;
store the values of each of the subcomponents in the memory;
combine the values of each of the subcomponents to determine pixel values for the one or more fibers; and
display the one or more fibers using the pixel values on the display;
wherein the one or more fibers are hair or fur fibers, and wherein the subcomponents of the light include:
a light that reflects off an outer surface of the one or more fibers (“R”);
a light that has transmitted through the one or more fibers (“TT”); and
a light that has been internally reflected off an inner surface of the one or more fibers (“TRT”).
11. The system of claim 10 , wherein the TRT is decomposed into two subcomponents including glints and the TRT excluding the glints.
12. The system of claim 10 , wherein properties of the one or more fibers include any of a color, an intensity, a longitudinal position and a longitudinal width, which is beyond a possible range of a physical based shader model applied to the one or more fibers.
13. The system of claim 10 , wherein displaying includes rendering a color, an intensity, a longitudinal position and a longitudinal width of the one or more fibers.
14. The system of claim 10 , wherein the user is provided with a direct control over defining the values.
15. The system of claim 10 , wherein:
the processor is further configured to:
provide the user with control over separately defining values for each of the subcomponents of a light scattering by the volume of fibers using the user interface, wherein each of the subcomponents of the light scattering by the volume of fibers controls a different visually apparent characteristic of the volume of fibers;
receive, from the user, the values of each of the subcomponents of the light scattering by the volume of fibers;
store the values of each of the subcomponents of the light scattering by the volume of fibers in the memory;
combine the values of each of the subcomponents of the light scattering by the volume of fibers to determine pixel values of the volume of fibers; and
display the volume of fibers using the pixel values of the volume of fibers on the display;
wherein the volume of fibers is a volume of hair or fur fibers, and wherein the subcomponents of the light scattering by the volume of fibers include:
a light that scatters forward and maintains its forward directionality inside the volume of fibers (“FS”); and
a light that goes into the volume of fibers and comes back to a surface of the volume of fibers (“BS”).
16. The system of claim 15 , wherein properties of the volume of fibers include any of a color, an intensity, a longitudinal position and a longitudinal width, which is beyond a possible range of a physical based shader model applied to the volume of fibers.
17. The system of claim 15 , wherein displaying includes rendering a color, an intensity, a longitudinal position and a longitudinal width of the volume of fibers.
18. The system of claim 15 , wherein the user is provided with a direct control over defining the values for each of the subcomponents of the light scattering by the volume of fibers.