CGTalk - Fog/Mist With Alpha Mapped Polies

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bobzilla

11-13-2006, 01:02 AM

I'm trying to use a fog or mist effect on some distant trees that are alpha mapped polygons, but the polies start to show through.

What's the best way to accomplish this without the polies showing up?

Thanks...

LucentDreams

11-13-2006, 02:08 AM

do fog in post, or cut the shapes of your planes to more accurately fit the silhouette.

bobzilla

11-13-2006, 02:12 AM

Well, there's hundreds of mapped trees, so doing it in post seems like the best bet.

Now I need to pick a post app...

basilisk

11-13-2006, 09:13 AM

the zBlur plugin can be used to generate a separate depth pass that will observe your alpha mapped trees. You can then composite this to create a depth fog.

If a plugin can do this then why Advanced Render can not is beyond me.

zBlur is on http://3dattack.net/shop/index.php?plugin=5

There are also things you can do with a huge visible light. Use an underground spotlight pointing upwards, turn off illumination, and play with the visiblity falloff settings. This can work with alpha mapped planes, though volumetric lights with shadows can have problems.

laurent

11-13-2006, 09:29 AM

did you try to use a higher raydepth count?
when ever I had prblems with alphas usualy the raydepth and shadowdepth was the culprit and uping it to 50 or higher fixed it.

bobzilla

11-13-2006, 11:42 AM

Thanks for the suggestions, gang. I will try some of these out.

Yes, increasing ray depth helped in some other alpha rendering problems.

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