> 1) There's black triangular shadowy bits on the height field that just don't
> look right. How do I get rid of them?

I guess this is caused by "the shadow line artifact". see 2.4.8  in the
docs.

> 2) The star is right in the top right hand corner of the picture and it
> looks squashed. I think that's got something to do with the camera but I
> have no idea how to fix it.

i do also guess this is camera distortion. smaller viewingangle recommended
as already has been mentioned.

> 3) The blue planet has a thin "atmosphere" that I made with a thin spherical
> shell containing blue-colored scattering media. The trouble is that the
> atmosphere cuts off abruptly and looks awful. How do I get spherical
> density_maps to work with scattering media so that the atmosphere drops off
> gradually? I can't get them to work at all; POVRay keeps complaining at me
> if I try.

spherical densitymaps are some kind of tricky. it is useful (or necessary?)
to create the mediacontaining sphere with a radius of one at the origin and
scale and translate it afterwards. for example when your planet has a
radius of 99 and the athmosphere has a thickness of 1 you should do

<code>
sphere {
  0, 1
  ...
  density {
    spherical
    density_map {
      [0.00 rgb 0]//outside
      [0.99 rgb <.5,.75.,1>]//this is where the planet ends
      [1.00 rgb 0]//inside
    }
  }
  ...
  scale 100
  translate <somevector>
}
</code> (uncomplete and untested)

> 4) This one's kind of subtle. The dust ring is also made of scattering media
> and circles the entire planet. There is a small region near the night side
> of the planet where light scatters from the ring and passes through the
> atmosphere but it ends up brown instead of blue. It's as if the atmosphere
> is absorbing the blue light from the scattered rays instead of scattering
> them again. Is that supposed to happen? and how do I fix it?

I'm not sure but i think this is supposed to be. see at reality. our
athmosphere scatters the blue light and appears therefore blue but when you
look at light that has travelled a long way through it the remaining light
is red and causes a beautiful sunset :-)

> Thanks a lot for your time.

never mind


btw: nice image for your first one

Regards Roman

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