I was just looking over some nice lunar texture maps when it was made clear to me that due to the back-scattering effect of the lunar soils the default render algorithm of Carrara makes a poor fit. Simply put, the moon is fairly equally lit from edge to terminator. It does not "shade off" towards the terminator, at least not by much. Any thoughts on how to approach this? I'm doing a couple stills, so I'm up for any kind of post-render trick, alpha channel stuff, or what have you. Or a way of building the right isotropic scattering into the shader (perhaps using the Shader Ops Fresnel function?)

Why not a fill light with shadows turned off - or am I being a touch simplistic?

Too simple...a fill light wouldn't respect the terminator. (Same problem with using ambience). I had some bizarre thoughts about making a flat moon, or using a gobo to cast the terminator, but at last I hooked up a "backwards fresnel" (fresnel in a mixer set to darken the texture instead of lighten it) -- and that worked okay for this project.

I'd be interested in seeing what you're talking about; I can't quite figure out what you were asking in the first posting. I do a bit of space stuff and would be interested in knowing how to make it as realistic as I can.... - Dex

Above, a test render with a fresnel darkening effect. There is by intention a rather high level of Earthlight filling in the shadow side.