Hi!
I was reading Arnold documentation of direct and indirect light sampling: https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_maya_noise_am_What_Is_Sampling_html
However, in the Diffuse Ray sampling section, I am confused with the diagram (attached) and the statement " Diffuse rays are sampled randomly over the hemisphere around the hit point."
The diagram shows one camera ray (sample, color in yellow) hitting a purely diffuse surface (I assume that is diffuse only) and further reflected in 4 different directions (color green). Now, my question is, if I shot only one sample per pixel, shouldn't the randomly directed diffuse reflected ray be also only one instead of 4? If we consider direct light sampling, then there might be a chance a shadow ray will try to hit the light (next event estimation). If I agree with this, then one randomly generated diffuse reflection ray, and one shadow ray- that make 2 rays in the figure. But it is showing 4 diffuse rays, could you please explain a bit?
That's what the Diffuse samples (in the Render Settings of whatever application you are using...since you are posting in the general forum, I won't assume) controls. By default, Diffuse (options.GI_diffuse_samples) is 2.
That means 2^2 diffuse rays are traced for every camera ray. On Arnold CPU.
On Arnold GPU, where there is no "ray splitting", there would be 1 diffuse ray per camera ray.
This is my first query in Arnold actually, so do not know the staff yet.
From the figure, I can see one primary (camera) ray, so I assume, there will be only one diffuse ray spawn in the scene. But those 4 diffuse rays actually confused me.
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