Re: Flat pan or circular pan? #capturing #howto #alignment

Olivier Cahen

Convergence in shooting leads to vertical disparity in  the corners of the image, and to a bad représentation of the distance scale.

Best regards, Olivier

Le 30 janv. 2021 à 15:51, Antonio F.G. <afgalaz@...> a écrit :

To converge or not?

For stereo viewing the answer is clearly NOT. The pair of images seen by the human MUST be equivalent to the ones taken by a pair of cameras perfectly parallel, and with the sensors in the same plane. This is the only way to prevent the dreadful vertical disparity.

And for shooting? Well, you can shoot with any convergence angle that suits for the scene, but then you must apply a perspective transform to get the images that would have been taken with an ideal parallel stereo rig. This is what stereo alignment is about.
Even though you can align ANY convergent/divergent pair, the alignment is easier if the pair is shot approximately parallel. But again, if need be there should not be any problem to converge the shoot.

This animated GIF shows how the images from two wildly divergent cameras are perspective-transformed to produce a perfectly aligned pair:

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