What is the secret to creating media steam/clouds? My two big problems
seem to be that I cant get the edge of each 'puff' well defined (not
enough contrast along the edge of the cloud) and that the edge of the
container object plays too much of a role in the shape of the puffs. I
just want puffs of steam shaped randomly, but which are within the
bounds of the container object, any thoughts? Also, what is the usual
pattern used for the density?
-- 
Chris Maryan
mailto: mar### [at] mcmasterca
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In article <383C9D51.BCA4D4F7@mcmaster.ca>, Chris Maryan
<mar### [at] mcmasterca> wrote:

> What is the secret to creating media steam/clouds? My two big problems
> seem to be that I cant get the edge of each 'puff' well defined (not
> enough contrast along the edge of the cloud) and that the edge of the
> container object plays too much of a role in the shape of the puffs. I
> just want puffs of steam shaped randomly, but which are within the
> bounds of the container object, any thoughts? Also, what is the usual
> pattern used for the density?

This is one of the things I originally designed my blob pattern for,
unfortunately, there is only a Mac version available, and it hasn't
made it into any other patches yet. The source is also available, of
course.

Another thing that can produce very good results is using an isosurface
function for the density, combining a conical density function with the
noise3d function. Of course, this also requires a patch, in this case
the Superpatch.

In the official version, I would try making spheres larger than
unit-size radius, giving their media a spherical density going to 0 at
the outside, and applying turbulence to this.(Try the turbulence on a
texture first, to get the parameters right. I would suggest a spherical
pattern for the texture, to get the closest results.) You need to make
the container larger than usual, because the turbulence will make parts
extend outward.
To get the edges of each "puff" well defined, use a color_map somewhat
similar to this:
color_map {
    [0.0 color Black]
    [0.85 color Black]
    [0.9 color White]
    [1.0 color White]
}
Simply make a bunch of these positioned along the correct positions. It
wouldn't be too hard to make a simple particle simulation just for this
scene, and use that to make the smoke flow. Or you may want to use a
kind of fractal shape, that might produce good results. You may need to
increase max_trace_level if you are looking through too many container
objects. It might be worth it to put all of the containers in a merge,
to remove interior surfaces(since most of them will be overlapping).

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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