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Topic: HSphSubD & InterpSmpls: Stratosphere to Earth in one paragraph.
posted by CPNICHOLS
archived on 1.5.2002
Can someone give me a better explanation of what H Sph. Subdivs. is and Interp. Samples? All I know is that increasing these values will increase the rendering time but smooth the image. I need a better explanation of what these will do in terms of image quality vs rendering time. I would like to know what the individual settings are:
H Sph. Subdivs.
Interp. Samples
and Subdiv on the Secondary bounces
Follow-ups
A: A very brief explanation:
Hemispheric subdivisions: determines the number of rays to send from a given point in order to evaluate the indirect light at this point. VRay evaluates indirect lighting by sending a number of rays in different directions and computing the light coming from these directions. If you send more rays, the result will be closer to the real value. Less rays will make the result noisy and blotchy.
Interpolation samples: When rendering an image with an irradiance map, the indirect light at a given point will be interpolated from a number of sample points stored in the irradiance map. These points and the indirect light for them are computed during the irradiance map calculation. Then during rendering, when VRay needs to know the indirect light for some point, it searches for the closest samples in the irradiance map and uses them to interpolate the indirect light. "Interpolation samples" determines how many stored samples to take in consideration. Taking more samples in consideration will blur the indirect lighting and will produce a smoother result. Less samples will make the image more blotchy and noisy.
Subdivs on the secondary bounces plays the same role as the hemispheric subdivs for the irradiance map and the subdivs for Direct computation. Note that this value is per GI sample. This means that if you have 10 subdivs for the first diffuse bounce, and 10 subdivs for the secondary bounces, then each of the secondary bounces will generate only 1 ray, and there will be a total of 10 rays. If the first diffuse subdivs are 10, but the secondary are 20, then each secondary bounce will send 2 rays and will give a total of 20 secondary bounces and so on.
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