groundplane: planar mapping
teapot: cylindrical mapping
red ball: spherical mapping
Ray bounce count=3
Ray Differential using 4 auxiliary rays, offset 0.1 pixelI don't do anything special to the refelction/refraction differential rays, just use ray differential as an sampling method.
Here are some problems about calculating texture derivatives. I using same delta for close and far ray-surface interactions.And if I use small delta, which will produce bigger texture derivatives, the image is gonna be more blurring on those closer pixels,but pixels with larger depth values will be more neat, vice vursa. So I finally use different delta based on the distance from the ray position to the film-plane.