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Of course my comment is too late, but still. If you use an undistorting mechanism embedded in “IM”, then you should exactly know how it works. It can be unpredicted sometimes.
I got this situation a few times.
But lets say properly that there may be a few cameras in scene, and each of them may have a few shots (when more than one physical camera used). In my case I got the “flipping situation” with all the shots of one camera. Undistortion was automatic (that is when you select distortion type as “constant” or use option “all shots have the same zoom"). And “IM” automatically undistorted shots with inversed (or just incorrect) distortion value. If then select type as “known” and set a proper distortion value manually it fixes the problem. Sometimes a several manipulations with distortion parameters helps.
Also setting the principal point as “known : 0.5, 0.5” may improve tha quality of calibration (I think the Autodesk is reasonably to set this option as the default in IM).
IMHO theoretically if you use a small perspective between the shot markers (for example the shots of a small object from far distance with a huge zoom, when your projection is orthogonal-like) you may expect that flipping effect as normal. Because the program may interpret your locator positions in two different ways - straight and inversed.
Author: JohnParamol
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