Mainstage Talks – Nov 2012 – Andy Gilbert – Shooting HDRIs & Lighting in 3dsmax with Vray

Vray Settings for this Scene

Irradiance map samples

Simplified:
Hemispherical Subdivs: controls the number of GI samples, the number of rays traced is a proportional the square of this number and also dependent on your DMC settings.

Interpolation controls how many samples will be used to sample the indirect illumination in a given point
Min and Max is the final resolution for the irradiance map, 0 being the same resolution as your image

Irradiance map samples

Nrm,Dist & Clr Thresh control how the samples are concentrated. I.E things closer togerher will get more samples

Basic Light Cache Settings

Suddivs = number of rays shot
Size = size of samples, smaller produce more detail, but also more noise and use more memory
Retrace threshold will reduce light leaks, and if use light cache for glossy rays is switched on it will prevent similar light artifacts

DMC Sampler

To simplify:
Increasing Noise Threshold, Adaptive amount, and reducing the Min Samples will decrease quality, for higher quality the opposite is true.
I tend to keep the adaptive around 0.85 and reduce my threshold to control quality

Image Sampler (AA)

3 Types:
Fixed
Simple and predictable, 1 = 1 sample at the center of the pixel
No Adaption so it can be less efficient/slower
Adaptive DMC
Good for small details, DOF, and glossy reflections
For very complex scenes with a lot of detailed textures the Fixed sampler can often be more efficient
Adaptive Subdivision
Great for large smooth areas and smooth textures, it will under sample (i.e take less than 1 sampler per pixel and be very fast.
Not good for detailed scenes (fur etc) or glossy effects