Recently I've been playing with Gilles Tran's cloud generation technique (to
whit: creating .dxf files from slices of monochrome pigments using an
animation loop, and then using the .dxf file to define a media density -
see http://www.oyonale.com/ressources/english/sources13.htm). I decided not
to use his actual MakeCloud macro; I thought I'd do it from scratch to learn
the ropes properly.

This image is my most recent effort. Getting the media settings right didn't
take too long, but I did have some difficulty balancing the solidity of the
cloud with its opacity. This sounds like the same thing, but I found that
the only way to make a cloud really opaque was to up the absorption. This
made the shadowed areas really dark (more like heavy smoke), when in
reality clouds tend to exhibit a kind of translucency. Adding a small
amount of emission cured this problem nicely.

More difficult is the shape. I think I've nailed the flat undersides that
typify low-level heavy clouds, but getting the rest of it to look suitably
'billowy' at the same time is quite tricky. I've settled on using an
isosurface to define the pigment (I find the shapes are easier to control);
this cloud is a small-scale granite added to a larger-scale bozo added to
tall hemisphere on top of an inverted flattened hemisphere (the latter
provides the flat underside).

Comments / suggestions for other refining the shape, anyone?

Bill

Post a reply to this message

Attachments:
Download 'cloud1.jpg' (52 KB)

Preview of image 'cloud1.jpg'