On Thu, 14 Oct 2004 13:46:00 +0000, Tail Kinker
<tai### [at] contrabandentcom> wrote:

>Somewhere along the ways I've missed an important detail...How does one
>set the aspect ratio in a PoV image?

I used to run into this problem all time back when I had my
Amiga.  The NTSC resolutions had a pixel aspect ratio of
10:11. The pixels were a little bit taller than they
were wide.  So if I rendered a sphere, I would get an
ellipsoid, slightly taller than it was wide.

Here is that I did (please excuse any wrapping):

  up <0, 1, 0>
  right <(output_image_width / output_image_height) *
(output_pixel_width_ratio / output_pixel height_ratio), 0, 0>

	That was my general formula.  Those are not pov
variables: you'de have to plug in values beased on what
device/format you were rendering for.
	so for a "normal" PC render:

  right <(640/480) * (1/1), 0, 0> 

	which reduces to:

  right <(640/480), 0, 0>

	Now for an amiga 640x400 NTSC render with those
10:11 pixels:

  right <(640/400) * (10/11), 0, 0>

	Adjusting the RIGHT parameter expands/contracts
the camera field of view left and right, so sometimes
things will get cropped off the right and left edges (contract)
or sometimes extra thigns will appear on the right and
left edges (expand).
	Since we are dealing with ratios, it is not necesary
to use the exact output file pixel dimensions.  I could use
4/3 in place of 640/480 with identical results.
	Off the top of my head, the wide screen TV format
is a ratio of 16/9?  If it is, then your right statement
for that format would look like:

  right <(16/9), 0, 0>

	Hope that helps.  Hope it wasn't too much detail.  :D
If there is any confusion let me know nd I'll whip up an
example and post it on the binaries newsgroup.


-- 
to all the companies who wait until a large user base becomes
dependant on their freeware, then shafting said happy campers with
mandatory payment for continued usage. I spit on your grave.

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