View Full Version : white circle artifact

Mr Rid
02-04-2011, 01:26 PM
What causes these little circles to randomly appear at the edge of F10 frames? Seems associated with radiosity. Am trying various settings, but have not narrowed it down.

Mr Rid
02-05-2011, 05:27 PM
After lowering the max pixel spacing, I got a black spot over a white spot. Turning down the rays per eval seems to lessen the frequency. Still dont know what is causing this. The previz scenes I am having this GI problem with are very straightforward, no plugs, nodes, or filters. Default GI, 3 bounce, FG interp. Geometry is only color mapped with pngs. The spots only randomly appear in the left (usually upper) edge of frame. I assume its connected with some random GI evaluation, in combination with ... Bueller?


02-05-2011, 08:11 PM
Can you post a simple example? It's pretty weird dave :)

(and you are not one to ask for assistance without testing thoroughly ..)

Mr Rid
02-05-2011, 11:22 PM
Oh, I am the king of 'never heard of that before,' as friends, mechanics, doctors, and tech support will attest.

I have not tested this one thoroughly to narrow it down, as I have many shots to setup. I am just avoiding radiosity for the moment. It may or may not have to do with the models or textures which I cant post. I hoped someone else had encountered these... anti-nans (?).

Mr Rid
02-06-2011, 04:29 PM
So, it seems to be the use of an 8-bit image in my skydome that Final Gather has this odd little problem with. It occurred to me that this was the only thing different going on in my scene, and the circles only appeared when the sky dome was somewhere in frame. The artifact disappeared after replacing with a 24 bit version.

I usually use 8-bit maps, except in skys where subtle gradients get noisy. This was just previz so it wasnt crucial. But who knows what it is about the encompassing dome GI that was bleeding some odd math at the fringe of frame. :question:

Mr Rid
02-12-2011, 03:27 AM
Today I got one circle on one frame, with no GI or 8-bit sky map, so I still dont know what is causing this. :bangwall:

02-12-2011, 03:32 AM
This might be a longshot, but have you tried applying Limit Dynamic range 0-1?

02-12-2011, 07:19 AM
Not sure but check your ray precision is set to 6, as I got some blotches with interpolated reflection similar to that, when I experimented with lowering it? Otherwise I am struggling to think what it could be?!

Mr Rid
02-13-2011, 04:17 PM
Yeah, I learned not to lower ray precision. When I get time, I'll have to try some tests on the most problematic scene.

This is up there with the weirdest glitches I've seen in LW, like a UV map problem I had with a penguin mesh. At about every tenth scene load, LW 9.3 would randomly misapply the UV and render little white holes in the color map. The same model had rendered fine in LW8.5 on a prior project. No subD, nothing wrong with the mesh or UV I could find, and too random to pin down.