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On Wed, 03 Jun 1998 03:48:45 -0500, Mike Hough <POV### [at] aol com>
wrote:
>As far as chopping off the top and bottom of the image, the tests I had done
>didn't require that, but I used the 1:2 aspect ratio recommended for spherical
images.
I'm not sure what you mean here. If you specify a right of 2x and an
up of z, you'll get an image suitable for mapping on an ellipsoid. If
you specify an image width of 600 and a height of 300, it'll still
have the views to the rear above and below, and they'll still need to
be chopped off to work correctly. ASCII art below.
Imagine you have a scene with two spheres, one in front and one
behind. Render it with ultra_wide_angle and an angle of 360*pi, and
you'll get something like this, without the dotted horizontal lines:
\_/
- - - - - - -
_
\ / \ /
| | | |
/ \_/ \
- - - - - - -
_
/ \
The sphere above and below is the same one as right and left, viewed
by looking up or down so far you're now looking backwards, between
your knees if you will, or bent over double with your hands behind
your head in a crab-walk. The image you need for mapping is the part
between the dotted horizontal lines, which mark the zenith and nadir
and should ideally be the same color, all the way across the image.
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