extrinsic_mat is not a file in the archive (Stereo setup - off-axis)

[celestialtaha]

Hello,

When trying to get the extrinsic matrix corresponding to the non-pivot camera (in my case the right one). It says 'extrinsic_mat is not a file in the archive '. My setup is off-axis. It seems that it just works for a parallel stereo setup.

[Cartucho]

Yes, I don't really know how to get extrinsic of an off-axis camera, since I don't really know what off-axis means. I was not able to find a way to get the world transform of the non-pivot camera either, so I hand-coded the parallel transformation using the baseline. I could do the same to the off-axis if I understand what it means.

Also for the disparity calculation, we need the images to be rectified, which in practice would mean that image planes are parallel. So probably for that case I wouldn't be able to generate disparity maps directly without having to rectify the images (which I would do using OpenCV).

[Cartucho]

I will google a bit more to see if we can get the world-coordinates of the non-pivot camera directly

[Cartucho]

Hi! So I made some progress on how to get the extrinsic matrix for both cameras but I am still confused about how those models work.

Anyway, the add-on should still work even when we do not know the extrinsic. It should simply send a warning to the user saying that the disparity can only be calculated, for now, in the case of parallel stereo. I will push a commit so that the add-on keeps functioning and shows the warning!

[celestialtaha]

Hi, I switched to the parallel mode for now. But to help solve this issue, I googled a bit and did not find any kind of geometric model for the transformation between cameras in this mode. If I find something useful, I will comment here.
This link describes the off-axis mode but there is no geometric model provided.