On Sat, Mar 15, 2008 at 9:33 AM, Leonard Evens
<[EMAIL PROTECTED]> wrote:
> To review, my basic aim is to produce very precise perspective
> transformations in order to merge panoramas which involve very large
Is there some reason you are not using hugin, which is a very capable
panorama stitching software?
> Unfortunately, there seems to be no way to specify target
> points except by dragging, but even given that, there is an additional
> problem. Typically, I have a facade in which the top and bottom may
> not be exactly parallel. In order to get them that way, I need to move
> corners on top and bottom of the building to desired positions. I can
> move the top corner more or less to where I want it. But when I try to
> move the bottom corner where I want it, I end up moving the top corner.
> (The only exception is when the original top was actually at the upper
> handle on that side. In that case, it stays at the new position when
> the bottom is moved.) If Igo back to correct the top, the bottom
> moves. You can iterate this process until you get it about right, which
> works well for moderate sized images, but for large images and precise
> positioning, it takes quite a while and is very frustrating.
> I've investigated the mathematics behind this, which involves projective
> geometry and cross ratios. Using that, I can determine where I have to
> move the upper and lower handles to get points in between to go where I
> want them to go. That would work, but the formulas are pretty involved
> and cumbersome to apply. I experimented with using selections, but that
> doesn't work because what is outside the selection is not moved and so
> lines can be bent.
> I don't see any other way to accomplish what I want except successive
> approximations or using the formulas. Can anyone suggest an alternate
> Leonard Evens <[EMAIL PROTECTED]>
> Mathematics Department, Northwestern University
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