Subject: Re: Simulating clouds
Date: Tue, 31 May 94 21:34:13 
From: djm2@isis.msstate.edu@ra.msstate.edu (Dan Murrell Jr.)

Andrew Nunn said on May 31 :

> Back in Imagine, create a hemisphere by adding a Primitive sphere and
> deleting half the points (z<0).Apply the large brush as a cylinder wrap
> (wrap Z) and set the Bright attribute. Position all your other objects,
> lights etc inside the dome. The effect is especially good if the camera
> moves because the the clouds also move around. The Bright setting ensures
> that no shadows get cast on the sky!
>
  Actually, an even better technique I've seen used with Wavefront involved
a very large grid (plane for us, with plenty of sections) with all the
corners and edges of the plane bent downward, and a cloudscape mapped onto
that.  That will give the distanced look where the clouds get thinner the
farther away they get from the camera.	So, to visualize this, it's kinda
like a gigantic net cast over your 'world' with it's corners tacked down,
thus pulling all the boundaries down as well.

Another technique that was recently discussed was Mike's suggestion to map
clouds onto a raised ground plane.  That gives you the distance look easily,
and extends infinitely in your view.  The latest enhanced version of Essence
volume I now includes a clouds attribute, which looks quite good, and would
be perfect for a seamless mapping on that ground plane.

Dan





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