Under what conditions do I NOT need to recalculate IM / LC ? (mainly for stills)

[JezUK]

95% of my work is static still images.

Under what conditions do I not need to keep recalculating the IM and LC ?

For example, if I am happy with the lighting and my camera view, and all I am doing is playing with materials, can I skip the step for calculating IM / LC ?

This would save me quite some time.

Any ideas ?

Many thanks.

[elivnA]

Materials and their colours affect your scene. You don't HAVE to do it, but things will look slightly weird if you don't recalculate, because of colour bleeding. But it all depends on how much the colours differ. Also, if you're making things see-through, make sure the stuff behind it has a proper amount of samples. And lastly, don't move your objects.

[Svetlozar Draganov]

GI should be re-calculated for every material/light/geometry change if you want to get an accurate result. You could of course use pre-calculated IM and LC when working on materials but like elivnA pointed out the color bleeding won't be accurate.

The only parameters which don't require re-calculating which I can think of now are Interp.Samples in Irradiance Map settings and Reconstruction Parameters in Light Cache settings.

The way that I usually speed up those process is to use Progressive Image Sampler and run a quick render on the entire frame for a minute or two, and then activate region rendering and only render a small part of the material that I am working on. Once the material starts to look like what I am after and run another quick full frame render and continue the process with region-rendering. You could use the same technique with Vray RT too.