GI artifacts question

[Christopher3D]

I'm exploring the demo version of Vray for Modo. I've only been doing this for a day, so forgive the questions if they seem lame.

I'm very familiar with how Modo and several other renderers work, so I'm not new to 3D. Vray seems a bit different in various respects.

In the attached image I see some GI artifacts and I can't seem to get rid of them. I have primary and secondary GI set to Light Cache, Light Cache subdivs is set to 5000 with Sample Size set to 0.007.

Modo has a variable GI cache size to deal with this kind of thing (as does Thea Render) and so that's what my thinking is looking for here.

Any ideas?

Thanks.

[Christopher3D]

Ok, nevermind. After doing more work I realized that using Irradiance Map is much better as a primary solver.

Sorry for the newbie panic!

[joconnell]

Light cache is pretty much only for secondary bounces - it'll do 100 bounces by default so make a very large "volume" of light compared to other solutions which kill off early for speed reasons. It'll filter itself a lot to smooth out the solution so it's best used for secondary bounces where there's little if any sharp detail in the bounce light compared to the first or primary bounce which irmap or brute force are far better for!

[Christopher3D]

Ok thanks. Yeah, I'm finding that irmap is much better.

[joconnell]

So the hierarchy is normally:

Animation / moving and deforming objects: Brute force and light cache or brute force and brute force (least complex to set up, highest detail since it's per pixel, can be grainy so highest render time)
Camera only animation / flythrough - no deforming objects: irmap and light cache saved to disk using camera path mode (no flicker, great quality, speed benefits)
Stills / print: irmap and light cache or brute and light cache

[Christopher3D]

Ok, that's very useful. Thanks.