probable bug and question

[Baptiste-AIST]

Hello,
First of all, I think there might be a bug in the colmap_project.py file Line 166:
self._src_image_path: Path = self._dense_base_path.joinpath('images')
I think it is supposed to be
self._src_image_path: Path = self._project_path.joinpath('images') ?

When I tried to load a project I think I got some problem loading the images.

Something else, I have a question regarding the transformations used between the extrinsics, and qvec.

I'm just testing few things, loading a colmap project from the .bin files of the sparse reconstruction.
I also exported as text the same project.

Now I'm comparing the values from the extrinsics matrices converted to quaternion using the rotmat2qvec() function and qvec from the images.txt and find some sign problem

This is the operation I'm doing:

R, t = extrinsics[:3, :3], extrinsics[:3, 3]

Rxx, Ryx, Rzx, Rxy, Ryy, Rzy, Rxz, Ryz, Rzz = R.flat
K = np.array([
    [Rxx - Ryy - Rzz, 0, 0, 0],
    [Ryx + Rxy, Ryy - Rxx - Rzz, 0, 0],
    [Rzx + Rxz, Rzy + Ryz, Rzz - Rxx - Ryy, 0],
    [Ryz - Rzy, Rzx - Rxz, Rxy - Ryx, Rxx + Ryy + Rzz]]) / 3.0
eigvals, eigvecs = np.linalg.eigh(K)
qvec = eigvecs[[3, 0, 1, 2], np.argmax(eigvals)]
if qvec[0] < 0:
    qvec *= -1

Here is an example result

extrinsics 3x3
[[ 0.84069511 0.52485483 -0.13326339 0.36173603]
[-0.05035232 0.32079831 0.94580817 -1.3479446 ]
[ 0.53916266 -0.78842618 0.29612123 -0.29920324]
[ 0. 0. 0. 1. ]]

qvec (from image.qvec)
[0.78383906 0.55312195 0.2144656 0.18345831]
transformed extrinsic to qvec
[ 0.78383906 -0.55312195 -0.2144656 -0.18345831]

from images.txt
IMAGE_ID 0.78383905532074405 0.55312195025968414 0.21446559699355383 0.18345830916316025 -0.21066262776005473 0.0066597845729506923 1.4117036089633237 CAMERA_ID NAME

I'm not too sure why the sign is different
PS: I edited the result from images.txt, it was correct

[meyerls]

The first part of not finding the image has been fixed. It really depends on the location where the images are saved. In the future, I will do a more sophisticated search for the image folder :D

In the second part of the issue, I will look soon!