I have been trying to use pix-sfm to refine camera poses in datasets of aerial photographs taken from a nadir angle (camera pointing directly down or 90 deg). Colmap usually does an ok job of getting these but after I run pixsfm.refine_colmap bundle_adjuster the camera positions are all over the place.

With oblique images (pointed somewhere between 90 and 60 deg) it seems to work ok.

I'm simply curious to know if anyone has tested this with nadir aerial photography and if there are any settings that can be used to improve the result.