[Radiance-general] estimating -av values, color

[Carsten Bauer]

Rob Guglielmetti wrote:

>
> Hey, now that would be cool.  Is there any way that could be added to 
> Radiance?  The ability to have multiple -av's for various materials 
> would increase the usability of -ae, I think. Especially for large 
> scenes that incorporate interior & exterior elements..


Hi Rob,
implementing this is more or less rather easy, I remember having played 
around with it some years ago already, but I didn't find it rewarding 
resp. worth the effort. The basic problem is always the 'flat' 
illumination caused by the constant value.

When it comes to image generation, if you have large scenes with 
exterior and interior parts both of importance for display in the image, 
and/or e.g complex stuff like trees etc, you should give the 'scene' 
feature of radzilla a try, with it's possibility of setting a separate 
parameter set meaning also separate caches.
It depends of course on the type of object. Computers are fast now, so 
even in million polygon octrees like a tree e.g a crude ambient cache 
with -ab1 and -ad 60 or 100 or so is trackable. In such an obect the 
errors caused by the crude cache are of no importance,  and  it 
definitely gives better results than any constant value  approximation.
In other cases, if the outside part is of lesser importance but still 
somehow visible in the image, setting -ab 0 and a constant av for the 
whole outside part might of course suffice, and it can save you the time 
and work of pasting some background stuff into the image with photoshop 
etc later..

-cb