I am currently reading the awesome paper by Jorge Jimenez about Character rendering : Next Generation Character RenderingIn the part about multi-sampled transmittance he uses some Poisson offsets and a jitter texture which contains [cos(x), sin(x)] and is used to rotate the the Poisson disk samples.But I am wondering how do you generate such texture ?Here is the part of the ppt which talks about this.
Jitter texture generation
opengl;rendering;texture;sampling;hlsl
The texture is probably generated by picking a random angle per pixel, and populating the image with its sine and cosine, remapped into [0, 1]:$$\theta \sim [0, 2\pi] \quad \to \quad \begin{bmatrix} \tfrac{1}{2} \cos \theta + \tfrac{1}{2} \\ \tfrac{1}{2} \sin \theta + \tfrac{1}{2} \\ 0 \end{bmatrix}$$I did a quick test and generated something that looks pretty similar (enlarged 4x):If you want to be extra fancy, then instead of picking independent random angles for every pixel, you might try stratified sampling or a low-discrepancy sequence. That may give better final results for whatever effect you're using the jitter texture for, due to better local sample distribution.