Hi.
Check these out:
http://www.rafal.stnet.pl/cumulus1.jpg
http://www.rafal.stnet.pl/cumulus2.jpg
http://www.rafal.stnet.pl/cumulus3.jpg
I've tried to create clouds like these but with no success. I have texture applied to: color, incendescence and opacity. I mean, the problem is to achieve this clean type cloud with this type of edge. When you look at clouds you see cool edge and density inside with soft shadows and some shadings I think. But when I wanna add similar edge in fluids by using texture opacity I get also some grainy stuff inside density becouse of texture I think, and with no applied textures the fluid look really bad.
Can somebody gimme some tips? I had enough battles with fluids settings 
Is lighting very important factor here. I mean real lights or fluids builtIn light? Do real lights give better effect?
r|m
You need to increase the shading quality to avoid dots around hard edges( render times will be longer ). Self shadowing is important. A good starting point is the fluid presets. If you've not done so, check out afternoonClouds.ma.
One trick to get a bit of ambient occlusion style shadowing in the cracks is to texture incandescence addition to density (the incandescence ramp should be a rather dark black to bluish grey ramp ).
Real lights are somewhat more flexible than the internal light, although they will take substantially longer to render. One useful trick with real lights is to use the decay on the light combined with careful positioning for fake shadowing.
Duncan
Thanks Duncan. You are the Boss.
I must check now all your tips.
r|m
Hi again.
I've tested afternoonClouds from Visor and found that second fluid is incredible important doing clouds. It's like additional air, right?
But I'm still not sure what makes clouds to have cool edge and clean density. Just check what I've cooked: http://www.rafal.stnet.pl/clouds2.jpg
The problem in these screen is these clouds look too much like cookies. When you compare it to cumulus clouds those have both sharp edge but also look soft.
I've tried to sets opacityInputGraph to make them more puffy but it isn't helpful coz they start to look like hard blocks/boxes, on the other hand when I try to make opacityInputGraph lower(increase it) they loose their volume.
I don't know but can it be density problem? I mean, I emit density from many diffrent surface emitters. All these emitters emit only: density--> 1.0 . I emit it for few frames only and set densityScale to about 10.0. Is there diffrence between emitting density from many surface emitters with high density example-->50 and decrease densityScale to something like 0.5? Or emit density--> 1.0 and put densityScale to higher values like 10 or 20?
My shading settings:
color--> constant;
incendescence--> Y_gradient, (I've tried with density here but in my case looks better with Y_gradient);
opacity-->density;
I also use internalLights becouse real_lights are too much time consuming for me.
Does heat emission important doing clouds or it doesn't matter?
P.S
Quick update. I just change dropOff, coz I have this one OFF. Now it's Y_gradient. It looks little diffrent but I don't think it solve the problem 
http://www.rafal.stnet.pl/clouds3.jpg
Also, look at the bottom of the pic, there are some artifacts I think they come from interaction between cloudsFluid and skyFluid.
r|m
The shadow opacity may be useful to you. With this relatively low( but don't set to zero.. there will then be no self shadowing) one can let light pass through the cloud volumes, which tends to soften them a bit. One of the cues we have to a clouds softness is the way light passes through them and scatters around.
However this can also lose some shadow detail if you are not careful. Also texturing the incandescence carefully can help get this glowy effect without losing some of the large scale shadowing.
With texturing of a fluid( as opposed to using a super high resolution density grid ) it is not possible to get a full range of hard and soft boundaries. One can try and adjust the opacity graph to have a fine wedge at the left for wispy stuff, but the way it gets uniformly applied on top of all the dense bits will not look natural.A workaround for this is to use a second fluid for the soft wispy bits.
The other aspect is that distant clouds merge with the color of the air, which is handled by the atmosphere fluid, as you noticed.
Heat emission doesn't matter for clouds unless you are using it for an effect or for a particular form of convection motion. You could do things like use the heat grid for incandescence and then paint the incandescence you want in places.
Duncan
Hey Duncan!
Many thanks for answer. Now I must check all your advices.
r|m
