Support for FOV camera model

[phuoc...@gmail.com]

Dear Johannes,

I was trying Colmap 3.0 on Gopro video with wide fov option. It appears from the code that the omega parameter should be estimated. Yet, the software always output 0 for omega. Can you please suggest if there are some silly mistake that I could have made? All the images were not intrinsically calibrated and I enabled shared intrinsic for all of them.

Thanks,

[Johannes Schönberger]

Hi,

See https://colmap.github.io/cameras.html#camera-models - it says "make sure to not initialize omega to zero". You can set the initial parameters in the database management. I will fix this soon and I am keeping track of this with this issue: https://github.com/colmap/colmap/issues/191

Thanks for the feedback.
Johannes

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[phuoc...@gmail.com]

I see. I was setting it close to 0 and there was a threshold that you set in the distortion function that essentially outputs 0 gradient. My bad!

What is a reasonable initialization/procedure to deal with FOV camera in your experience because the nonsense initial guess will affect the correspondence estimation step in 2 view matching.

[Johannes Schönberger]

Setting it omega=1e-3 should produce minimal distortion effects and hence not affect the two-view matching too much. If you want to be more precise, you could first set omega=0 during the matching and then omega=1e-3 before starting the reconstruction. Makes sense?

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[phuoc...@gmail.com]

It works now. Thanks!