Standard Max Lights = Much Faster/Less Noisy than CRN Lights.

[atelieryork]

Hi folks,

I'm struggling to find a reason to use CoronaLights. I would have assumed that they are the preferred option for lights, as per VRay/Mray etc. but in my testing I'm finding that some CoronaLights on some occasions (I can't find a pattern here yet) are causing all lights in the scene to render really, really noisy. As soon as I disable those lights the scene renders very cleanly. If I replace those CoronaLights with Standard Spots or Omnis with CoronaShadows the results are very smooth and quick. Examples would be uplighters underneath trees or omnis inside rooms of a tower block.

I'm either doing something wrong (which is definitely possible!) or CoronaLights are occasionally causing major noise issues.

I can't upload a scene I'm afraid, due to NDA, but I've found this on a couple of totally different scenes now.

My hunch is that this is a bug. I'm going to keep testing to see if I can nail it down.

Cheers,

[Ludvik Koutny]

3ds Max native lights usually render lot faster since they are not physically based. Difference in regular rectangular are light will be minimal, but difference in spot light may be extreme. Directionality parameter in CoronaLight is physically based anisotropic light distribution, whereas 3ds Max native spot light cone is a simple fake. Same goes for IES lights. Simple things like area light rectangle or sphere should render at nearly same performance when it comes to CoronaLights vs 3ds Max's native lights, but more complex lighting effects line focused light distribution or IES will make a huge difference.

BTW there is also a bug with Disc shape of CoronaLight that causes a lot more noise than it should. It will be resolved soon.

But by all means, use 3ds Max's native lights as much as you need to if you see performance benefits. I am doing the same. For example street lamps at evening have cone light distribution. With mulitple CoronaLights with directionality parameter, this would render very slowly. With 3ds Max native lights, this will render much faster.

[atelieryork]

Thanks Raw.

I suspected there is a bug with the disc shape CRN light. I have just swapped them over for rect shape and the problem remains the same, however, so perhaps this is not the root issue...

Like you I have found that the standard native max lights are way, way quicker to render and are generating perfectly acceptable results. But it's not a workflow I'm enjoying. I'd rather get everything working properly fully within the CRN physical "world".

Thanks for your input,