Peter Kryszkiewicz wrote:
> 
> I'm trying to simulate daylight coming through a window, like that classic
> Vermeer scene on the cover of Computer Graphics by Foley et al.
> 
> I can't get my window pane to cast much light into the scene at all. I've
> set ambient to 1 for the window and turned off all other ambient values in
> the scene, then played with the variables. Is this a clamping problem in the
> POV radiosity code, as I've seen mentioned before?

No.  The color values returned by sampling rays are not clipped in
POV-Ray.  Same applies for the samples stored in the cache (you can check
the cache file if you don't believe that).  The only place where values
are clipped is when reusing them.  Therefore you can use ambient finishes
with ambient > 1 without problems.  The only difficulty arises when the
stored illuminance values exceed 1.

> If I play with the POV source (volunteer to improve) is there a place where
> I can easily add a capability to increase the effective brightness of an
> arbitrary radiator to a value higher than ambient 1? I guess I'm talking
> about simulating a very strong area light, which is what daylight coming
> through a window is supposed to look like in a radiosity scene.

If you want an area light, use an area light.  There is no point in trying
generate light source effects with ambient objects.  Sunlight coming
through a window should be made with a light source placed outside,
skylight with an ambient sphere/sky_sphere.

Next MegaPOV will contain a patch for removing the clipping.  You will
however recognize that it won't make much difference in most situations.

Christoph

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Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

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