Tracing Ray Differentials

Homan Igehy

Speaker: Haoji

• Ray tracing

• ray differentials– derivatives of the ray with respect to image

space coordinates, by applying the derivatives of the functions.

Initial value

Transfer

Reflection

• If we know the formula for how a ray is affected by a phenomenon, then we can differentiate it to get a formula for how a ray differential is affected without any understanding of the phenomenon

Texture Filtering

• If we can approximate the difference between the texture coordinates corresponding to a ray and its neighboring rays, then we can find the size and shape of a filtering kernel in texture space.

pixel’s footprint in texture spacebased on the pixel-to-pixel spacing:

• Given this parallelogram, one of several texture filtering methods can be used – mip mapping

• level-of-dital =>