Final Presentation

Extension to GPU based path tracer

By- Gundeep Singh

Extended my path tracer

• Features added-:a) Obj Mesh Loaderb) Subsurface scatteringc) Cook Torrance BRDFd) Fresnel reflectione) Interactive Cameraf) Depth of field g) Motion Blurh) Post processing effects for fun!

• Implemented a Obj Mesh Loader to handle arbitrary geometry.

Interactive camera• Controls to move within the scene.• The path tracer is reset after every camera

movement.

Subsurface scattering• Subsurface scattering(or SSS) is a mechanism

of light transport in which light penetrates the surface of a translucent object, is scattered by interacting with the material, and exits the surface at a different point.

• To mimic effects of materials like milk, wax etc.

i oxi xo

s

Subsurface ScatteringBunny- 1100+ faces

Reduction Coefficient= 2.0

Depth of field• Earlier we are

using pinhole camera now to implement depth of field we assume some size of camera.

• Simple and most important concept for DOF is to jitter the location of ray start (i.e camera position) and construct a ray using that camera position.

Motion blur• Simply translating the objects between

frames rest is taken care by the path tracer !

KD TREE

• Was unable to complete implementingCukd.

• Needed some more time for that

Cook Torrance• What makes the Cook-Torrance shading

model so favorable?o First, it computes its specular lobe using the half-angle

vectoro Second, it accurately models the Fresnel effect,

increasing the specular reflectivity as the surface turns away from the viewing direction.

o Finally, it models micro imperfections in the surface

Cook Torrance Results

Roughness= 0.2Gauss Constant=100

Roughness= 0.02Gauss Constant= 50

Some post processing effects

Contrast Gray Scale

References• Real time rendering book.• Pixar Cook Torrance http://

renderman.pixar.com/view/cook-torrance-shader• KD trees

http://graphics.stanford.edu/papers/gpu_kdtree/kdtree.pdf

• Subsurface scattering http://en.wikipedia.org/wiki/Subsurface_scattering

• Depth of field http://http.developer.nvidia.com/GPUGems/gpugems_ch23.html

Thank You