[Radiance-general] RE: ambient exclude list -ae

[Thomas Bleicher]

On 11 Apr 2007, at 21:43, Martin Moeck wrote:

> Hello,
>
> I'd like to exclude a red sky from the indirect calculations, but  
> the -ae switch fails.

The 'ambient exclude' switch only works on materials that do
participate in the ambient (indirect) calculation. A small
part of my memory says glow materials are never considered
in indirect calculations. So your '-ae' will have no effect
on the glow material.


> The scene is listed below. The scene is rendered as follows:
>
> rview ... -ab 1 -ae red (or redsky) octree
>
> The object sc.oct turns red. This should be avoided. What is the  
> issue here - the material glow?

I'd say so. You have defined a red sky (and ground, btw) and
some sort of directional light. If you render it with only one
bounce all faces that are not in direct view of the light source
_only_ get light from the sky. That's what you can see.

You can try to add a limiting radius to your glow definition
(forth argument). I think a value of 0 means that the glow
has an infinite range (or none at all? - the old doc I have is unclear
about that). If you set it to something small like 0.1 it might
limit its effect. But I don't know how this works when the glow
is applied to a source which has no measurable distance to the scene.

I assume all you want is to render the object on top of a red
background, right? In that case you could try to render the
object _without_ sky which gives you a black background (use
'-av' to avoid black faces on the object). Then use pcomb to
colour all pixels with a value of 0 red. See the 'stencil' thread
of a few weeks ago for an idea how this might work.


Report any success!

Thomas