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Johnny
02-23-2006, 01:31 AM
wondering if there are any new tricks out there for dealing with flickering textures? I'm talking about textures in which it looks like there's a fine grit which is vibrating or shimmering...similar to what you see when a TV station goes off the air.

I have tried: cranking mip-map, cranking AA, motion blur, camera gradient trick, using maps of high-resolution, using NO maps.

While I have *reduced* this flickering, it's still there to some extent and some of it is downright maddening!

One of my objects that has this grit only uses a procedural to make large grooves in the object, say 1/4" apart. this object looks like its COVERED with this flickering grit, so I've killed specularity and gloss.

I'd be grateful if anyone could share their secrets on this...I know such victories are hard-won.

Right now, I'm looking at either putting up with flicker grit, or...dumbing my scene down to the extent that it doesn't matter if I'm using a world-class 3D app or not.

thanks!

J

Lightwave7871
02-23-2006, 01:57 AM
Are you rendering out on a render farm? I've seen render farms with different types of CPU's in individual nodes generate different fractal patterns.

Another thing it could be is a moire pattern if your grain pattern is too fine...

And last guess, is it could be down to your lights, are you using Spotlights with shadow maps and if so what are your settings on the shadow fuzzyness, because I've found that if the shadow fuzz gets above say 15 - 20 then the shadow breaks up in to a buzzing grain.

Sadly the only way around this particular issue is to drop the fuzzyness down or replace the Spot with an Area light, which obviously incurrs a render time hit.

I hope I'm not teaching you to suck eggs... good luck.

Johnny
02-23-2006, 02:14 AM
I have 2 identical macs doing my screamer rendering; same model, same RAM, same speed.

My scene does have some moire, but this grit I'm talking about can be seen when the cam is dead on, and where there "shouldn't" be moire..IOW, where patterns or textures aren't all that fine. the grit seems to be on top of, not a part of whatever texture is there.

I have 1 area light and several spots..I could see if killing the spots' shadows makes a diff..

I might have to replace those with an area light for casting the shadows they cast.

thanks for the ideas...I'll be looking at them.


J

starbase1
02-23-2006, 02:47 AM
I have seen this happen when you have 2 copies of an object / some polygons in the same place, (either duplicated in Layout, or duplicated in Modeller)

If you can identify a surface involved in the messy bit, try setting it's surface to 100% transparent, and see if that reveals something...

Are still images OK or does it only show with animation? Can you show us an image?

Nick

Johnny
02-23-2006, 01:17 PM
I have seen this happen when you have 2 copies of an object / some polygons in the same place, (either duplicated in Layout, or duplicated in Modeller)
Are still images OK or does it only show with animation? Can you show us an image?

Nick


Hi, Nick;

I'm pretty sure (95%+) that there are no duplicate polys, but I'm going to look at that possibility.

Stills are just fine; the squirming/flickering happens during animation, which, in this scene, consists of camera motion only.

I'll post an image today maybe; I'm running down another possible fix and hope to have a clip to look at soon.

thank you!

J

RedBull
02-23-2006, 04:27 PM
This problem is an inherit problem of 3D rendering, (not just LW) and it won't ever be fixed, the idea is to minimize it as much as you can with various techniques. Higher AA settings, the new resconstruction filters and PLD passes, can help in some situations too....

Alpha's and camera to object gradients are a good method,
various distance gradients on procedurals on bump channels also help....
I also use WaveFilter Image - Image Filter to sometimes resolve it...

Rendering in double or quad resolution, and then downsampling
via an integer bicubic downsize can often also be better.....
(do not do bilinear or NN as this is similar to what LW is doing.)

Johnny
02-24-2006, 12:26 PM
OK..I guess we're stuck with some level of it, then..I'll be happy if I can get it down to the less-than-totally-obnoxious level, which I think I can do.

cheating will be involved, however...

J

JamesLeaman
02-25-2006, 12:23 PM
sometimes if you cache any light shadows or radiosity you get flickering like a strobe effect!!

kopperdrake
02-25-2006, 08:02 PM
Best way I found of minimising it is to render with motion blur turned on, over 9 passes.

Johnny
02-25-2006, 09:09 PM
any particular settings you like to use with motion blur for that purpose?

thank you!


J

toby
02-27-2006, 01:11 AM
Procedurals and/or bump maps can cause this and be very hard to get rid of. Depending on what it is and how bad, you may need extreme aa to cure it.

I once had a spaceship covered with crusty bump, and had to use extreme to stop the sizzling. Took 5 days (with radiosity) but it looked SO cool.

kopperdrake
02-27-2006, 04:16 AM
Start at classic setting medium enhanced AA with motion blur at 50% (default) and then work your way up the AA settings - extreme etc. If i get over medium enhanced for an anim then I really think about changing the textures. If it's a line of narrow bumps what about using a bump map which always seems to moire and flicker a lot less - you can blur it slightly to make this even less obvious.

Canyou post an example frame of your anim so we can get a better idea of what you're trying to achieve?

Dunk