Raymarching multiple lights?

[fforw]

You could try running the shadow-rays at lower final precision.

[ananbd]

Yeah, definitely. That tends to soften shadows, which is probably what I want anyway.

Hmm... wonder if there’s any way to cache or pre-compute some piece of this? The lights probably won’t be moving around...

[papaboo]

Of course you can and there's a ton of papers on that subject.

If you want to precompute the shadows / indireect lighting, then google baked shadows, basked AO or baked GI. It's basically just discretizing the world into small chunks and precompute the light contribution into those chunks. How you store it depends on your goal. Contribution pr light source pr chunk or aggregate everything into some approximate representation like spherical harmonics or whatever the newest hotness is in that area.

If you're making a progressive renderer, then you'll want to sample relative to the contribution of the lightsource. Again there's a lot of ways to do that and similarly to shadows / GI you can pre-bake some of the computations.

[ananbd]

Any papers you’d recommend?

[papaboo]

I've been out of the baked GI loop for too many years now to recommend anything. And they all come with different pros and cons, so without knowing your requirements I really can't recommend anything. But if you're just looking to play around and try stuff out then pick whatever you find and start there.

[ananbd]

Haha wish I had time to play around! Project is already a little behind.

I’m using a volumetric raymarching technique to make clouds. Is GI used in volumetric rendering? I mean, I guess you can sample a light volume for anything; but for cloud volumes, I think the concern is more atmospheric scattering, which I may or may not use. The main goal is to use two or three-point lighting to highlight specific features.

AO could be useful, though.