In article <3f32208f$1@news.povray.org>,
 "David Wallace" <dar### [at] earthlinknet> wrote:

> Maybe I need to make my goal more clear -- I want an image-mapped sky to
> work with radiosity.  I could care less if the technique is by sphere or
> sky_sphere.  I have seen a link concerning how to eliminate the crunching
> effect at the poles of image-mapped spheres, but I don't remember off
> the.top of my head where it is.  A large hollow sphere placed far below the
> scene will probably suffer from this phenomenon unless corrected.

You could just use a planar projection for the image map. It will be 
distorted, with the effects getting extremely bad near the "equator", 
but the effects will be small in the area of the sphere you will be able 
to see. You don't say anything about the source image: what projection 
it uses, what it's intended to be mapped on...

You also need to clarify the "to work with radiosity" part. How does 
what you're doing not work with radiosity? I didn't think this is the 
case, but radiosity may ignore the sky_sphere. If that is the case, you 
can just put the pigment on a big sphere...but you apparently already 
know how to do that.


> > I dislike plane skies, for their infinite horizon effects. I recommend a
> > big hollow sphere centered far below the scene instead...I do not find a
> > plane to be "good enough".

And another thing: for many scenes, the inaccuracy of a sky_sphere sky 
is perfectly acceptable. If the scale of the visible part of the scene 
is small compared to the altitude and extent of the clouds, you will 
have a hard time finding any difference. For an indoor scene with a view 
out the window, or even most outdoor scenes, a sky_sphere is fine. If 
you have an ocean view stretching out to the sunset, it won't work 
right...though it may still look right, if the appearance of the sky is 
fairly even.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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