Random colour flashes within output

[busseynova]

Vray 3.6, BF/LC GI with subdivs on 3000, and retrace on 8.

Got these random colour bursts on a couple of frames. It is reproducible. Not the neatest of scenes to be honest, as it came from a gargantuan Revit file.

Anyone care to help me narrow down my field of troubleshooting? GI issues or material issues?

colours look a bit odd as I converted from 32bit

[super gnu]

did you check for non-vray materials in the scene? vraysceneconverter can help, but it often misses some. also, do you have the secondary ray bias on a low non-zero number (0.001 for example)?

[busseynova]

No, and that was going to be my first point of call, but get this:

I changed GI Subdivs up to 4000 - problem went away. Changed it back down to 3000 - and it didn't come back!

What the hell.

Could have been the surface behind the green wall actually. Wasn't meant to be renderable but it was.