"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> It works a treat, but often I find that the rotated image doesn't quite match
> the other image after unwrapping. The points I select in the editor match
> perfectly, naturally, but the images seem to diverge near the edges. I'm not
> entirely sure why this is happening, but making sure the ball is centred in the
> frame when taking the pictures seems to help considerably. Can any resident
> HDR-makers shed any light on this?

I'm not an expert on this, but AFAIK virtually all real-life cameras exhibit
some distortion of objects not precisely in the center of the frame.

It's basically the same effect as can be seen with POV-Ray's standard
"perspective" camera: Place two spheres side by side - one in th center of the
image, and one at the side. Crop both shots to the spheres' dimensions. You'll
notice that the off-center sphere does not seem to be circular.

AFAIK it is mathematically not possible to design a camera that produces planar
2D images without any such effects.

The more zoom you use, the less prominent these distortions should be.


If your lightprobe-generating software takes already-cropped images, it will
most likely be unable to determine whether your chrome sphere was off-center in
the original shot, and silently assume that it was taken head-on.

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