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sean hargreaves
10-18-2007, 02:58 PM
Hi guys, I'm having fog issues, as in, it does'nt look right!

I've got a city street and I want fog or haze to give depth. I've gone to the effects window and gone through the fog type volumetrics. It just does'nt look right, I mean, the buildings are going grey, and they are the same grey no matter how far away they are. I increase the fog and they all just go greyer.

Any fog masters out there?

Surrealist.
10-18-2007, 04:08 PM
Have you tried changing the fog color? Use a color that integrates into the scene well so it is not just turning gray. For instance if your scene is predominantly browns use a deep dark brown with a lot of black.

You could also do the same thing with a sprite that was large enough to fill the entire scene and have it fade off gradually which will give you more volume. With a low contrast texture you could get a similar thing to fog but perhaps some of the depth you are looking for. Again integrating color or even using a color that depicts depth (as in the bluish or purplish you see used in paintings of mountains in the distance to create depth perception.) will help. In fact there is a whole art just to choosing colors that invoke a perception of depth.

Depth Color Chart
http://www.physics.utoledo.edu/~lsa/_color/19_color.jpg

Some links:

Overall depth perception including color (chart above). (http://www.physics.utoledo.edu/~lsa/_color/19_depth.htm)

Depth Perception with Color (http://books.google.com/books?id=SpcaPcCxFPgC&pg=PA124&lpg=PA124&dq=depth+perception+colors&source=web&ots=a14gLpnYK6&sig=RnfNWT_BRL8vTpMchStQGCcWd28)

Chromo Stereoscopic effect (http://www.cg.tuwien.ac.at/~wallisch/chromadepth/index.html)

sean hargreaves
10-18-2007, 04:59 PM
Hi Surrealist, thanks for the tip. But I have no idea what a sprite is.

All I want is fog that gets denser with distance. The opacity of the fog does'nt vary using te volumetrics window selections, thats the problem.

Sekhar
10-18-2007, 05:20 PM
Sean, attached is a test render and the associated settings. Is this kind of the look you're looking for?

SplineGod
10-18-2007, 05:41 PM
A sprite is a type of hypervoxel.

sean hargreaves
10-18-2007, 05:41 PM
Hi Sekhar, thats good. But what I want is this same effect in a horizontal manner, so that the fog is denser farther away. Here, the fog is denser as it is lower. I say fog, but its really haze I'm looking for, similar thing I guess.

Any suggestions for settings?

Sekhar
10-18-2007, 05:59 PM
Sean, fog does get denser with distance. The denseness you're seeing at the ground has more to do with the "top" setting - I increased that so it doesn't come into picture.

See below another test with multiple cows. As you can see, the visibility goes down with distance.

gerry_g
10-18-2007, 06:49 PM
I used volumetric fog which does get denser with distance, but when I turned on the custom color option my fog disappeared boo hoo

sean hargreaves
10-18-2007, 06:50 PM
Thanks Sekhar, I fiddled around a bit and I'm getting there, thanks for your help.

Also, I just noticed FPrime does'nt work with volumetrics. Aaaarrrggghhhh!:thumbsdow

JamesCurtis
10-18-2007, 09:26 PM
I kinda came in the middle of this thread, but had a similar question. What would anyone suggest for a way to do fog that hovers slightly above the ground a bit? Like a mist?

SplineGod
10-18-2007, 10:30 PM
This ground fog was done using geometry.
http://www.3dtrainingonline.com/examples/ground_fog.jpg

Mr Rid
10-19-2007, 12:19 AM
I kinda came in the middle of this thread, but had a similar question. What would anyone suggest for a way to do fog that hovers slightly above the ground a bit? Like a mist?

Well there is the oft overlooked Vfog pixel filter (that can do some odd things).

Another trick is to play with a volumetric Distant light. Many dont realize you can even do that. Back when Fog never worked right with transparent objects, I would parent a distant light to the camera, placed at the distance you want the max fog level, and aimed at camera with appropriate falloff. Then you can even run a texture thru it to break it up or use gradients and whatnot for all manner of FX.

Surrealist.
10-19-2007, 02:59 AM
I kinda came in the middle of this thread, but had a similar question. What would anyone suggest for a way to do fog that hovers slightly above the ground a bit? Like a mist?

Also try this:

Add a null.

Give it a sprite and texture it with a cloudy texture (I used turbulence) then use the Y scale in the geometry tab (of the Volumetrics) to squish it down. I used 20%.

Position the null near the ground.

Light it.

Note: The mist is above what is supposed to be water.

JamesCurtis
10-20-2007, 09:27 PM
Thanks for the tips everyone!!