Save points2D and points3d_idx in images.bin

[mateoTWD]

Hi,

I am trying to save the points2D and points3d_idx in the file image.bin and after a lot of trouble with the format of the binary and the indexing of the tracks I managed to make it. My issue now is that it seems like the points2d_idx saved in the points3d.bin are global for the total number of keypoints in the scene instead of local indexes for each image keypoints, so after trying to index my 2d points saved in images.bin with the indexes saved in the points3d.bin I obtained an out of range error (doesn't happen with the basic pycolmap for example).

Any clue of where in the code can I solve that?

[jiahaoli95]

Thanks for catching this. I will fix it on the weekend and let you know.

[jiahaoli95]

Hi @mateoTWD I fixed the problem in #8. Could you give it a try to see if it works? Thank you!

[mateoTWD]

Hi @jiahaoli95 , it saves the points correctly but i don't know if the indexes are well referenced. I am trying to sample some 3d points and get all the 2d points related to that 3d point in order to compute the distance of that keypoint to the camera by calculating the distance of the 3d point to the center of the corresponding camera. After that I do a regression with the lidar depths of an iphone in order to get the relation between the real distances and the fastmap distances. But the results are wrong (with colmap, glomap, pixsfm and openmvg works correctly). Maybe the 3d and 2d indexes are not well related? I can give it a try if I have some time but now I'm quite bussy.

[jiahaoli95]

Thanks. Two more questions before I dig more into this.

1. Do you mean that with the above PR the out of range errors no longer appeared?
2. Have you tried visualizing the fastmap results (cameras poses and point cloud) with either the fastmap or colmap visualizer, to make sure that fastmap does not fail on the scene?

[mateoTWD]

1. Yes, there is no error now (the points are saved and all the process ends with no errors).
2. Yes the scene is allright (intrinsics, poses and points 3d correct). Maybe is a problem with my implementation of the process I have told you, but I don't know now how to check if the keypoints saved in the image.bin and the points3d_ids are all well connected.