Warp <war### [at] tagpovrayorg> wrote:

> In the more general level, this is the basic problem with open surfaces.
> A HF is an open surface and thus these types of artifacts are to be expected,
> as with any open surface. Only closed surfaces behave "correctly".

I decided to run the same experiment on the other "triangle-based" surfaces POV
offers-- bicubic_patch and smooth_triangle mesh--to see what their behavior
might be. (I generated these in the sPatch app, as simple flat surfaces, and
ported them over to POV as .inc files, using sPatch's various export plug-ins.
AFAIK, the sPatch plug-ins don't create any kind of "specialized"
patches or meshes; they seem to be of the same syntax as POV's own.
BTW, I didn't try a "flat"-triangle mesh because sPatch doesn't export those.) I
then cleaned up the files to make sure that there were no unions or other
elements in there.

I should clarify that the fog I used for this experiment is the simple gound-fog
statement (not atmospheric media or object media):

fog {
  fog_type   2
  distance   2
  color rgb .7
  fog_offset 0
  fog_alt   .7
}

The result is that neither of these objects exhibit the infinite-inside-space
behavior that a HF does. (I tried every trick to MAKE the fog disappear, but I
couldn't get it to.) So it seems that a height_field is the only
"triangle-based open surface" object that does this.

Ken

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