Mike wrote:
 >
 > I can not seem to get the angle keyword to have any effect
 > whatsoever with panoramic cameras despite the documentation's claim
 > to the contrary. More generally, I'd like to know which camera
 > types should use the various values like up,direction,right, and
 > angle and in what order they should be specified (since this seems
 > to make a difference).
 >

Mike,

at the time I wrote a patch for POV 3.1 some months ago (creating
stereoscopic images), I noted that angle and aspect ratio were rather
confusing and behaved not the same way especially for the panoramic,
fisheye (and the like) camera types. In Megapov there are some patches
to the camera section, and IIRC these were adapted for POV 3.5
So I am now curious, what happend to this part of the source code...


Anyway, if you are confused on how a camera behaves, the best
way in my opinion is to set up a small camera test scene with a
very defined geometry. I used a scene with camera at origin and
a circular structure around it with cylinders (as marks) every 30
degrees. So one can find out empirically, what "angle" does.
It is helpfull to render this test scene with quadratic
image aspect ratio (i.e. right=up)

With respect to the camera parameters, I find it usefull to
distinguish "basic parameters" and "convienience shortcuts".
The former completely define a camera, but are often tricky
to set up, wheras the latter are only a more convienient way
to set up the former.

location, direction, up and right are "basic parameters"

angle is a "basic parameter" for some (all?) panoramic cameras
and for fisheye, but it is a "convienience shortcut" for the
standard pespective camera (it adjusts the direction vector
i.e. the focal length).

sky and look_at are "convienience shortcuts".

hope this helps a bit.

Hermann Vosseler

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