The problem is that the Cartesian system of describing a 3dimensional space doesn't
allow for proper calculations when the
camera points straight down like that. The up vector goes from y to <0,0,0> and
rotations are mathematically impossible. I
don't have all the mathematical details here, but the calculations jump to infinity in
this situation. My brother works with
aerodynamics and he had to work around this by using quaternions.

Josh

Dawn McKnight wrote:

> Someone recently posted on here that a crash is always an error; that
> the appropriate action for the program to take if there's something
> wrong is to give an error message, not to crash.  So I'm posting this
> code, which makes POV do just that.
>
> I am using POV-Ray, version 3.1g for Macintosh, on a G3/300 running OS
> 9.0.4, with 160mb RAM.  I know code shouldn't normally be posted in this
> group, but this is /really/ short, as I was looking at how height fields
> work.  I suspect my slopes are too abrupt or too confused, but here it
> is.  You can find the image I was using to create the height field at
<http://www.coyotesdaughter.com/dawn/newworld.gif>.
>
> #include "colors.inc"
>
> light_source { <0, 10, 0> White }
>
> camera {
>         location <0, 3, 0>
>         look_at 0
>         } // close camera
>
> height_field {
>         gif
>         "newworld.gif"
>         //smooth
>         pigment { Red }
>         }
>
> --
> Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
> McK### [at] maccom   |                                    -- Justine Devlin, M.D.

--
Josh English -- Lexiphanic Lethomaniac
eng### [at] spiritonecom
The POV-Ray Cyclopedia http://www.spiritone.com/~english/cyclopedia/

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