noise threshold and irradiance map.

[super gnu]

Hi, could somebody explain how the noise threshold in the dmc settings affects the imap quality? ive noticed changing it seems to change the calculation time and blotchyness, but i dont understand what parameter(s) of the imap the threshold is modifying.. does it somehow modify / override the imap threshold parameters?

thanks, Robin.

[super gnu]

bump...anyone?

[vlado]

The threshold changes the number of hemispheric rays that are shot for each of the irradiance map samples and so determines their "quality" (whereas the irradiance map thresholds are concerned with spacing the sample points themselves).

For example, if you have 50 subdivs for the irradiance map, this mean 2500 hemispheric rays for each sample. However in many cases it is not necessary to trace all of them, so V-Ray first traces several rays, looks at how different they are from each other, and decides whether more rays are required or not.

The noise threshold is involved in deciding whether to trace more rays. A higher threshold will tell V-Ray to stop earlier, but the result may be quite far from the real value. This would lead to differences between adjacent samples, and from there - to splotches. Lower threshold values will cause V-Ray to trace more rays so that it can get a more accurate estimate for the GI at each sample.

Best regards,
Vlado