Using alternative bundle adjustment solver

[Antonin Kenens]

Dear COLMAP team,

I am currently working in my research on nonlinear least squares algorithms in Julia in Polytechnique Montreal. I use bundle adjustment models as test problems.

My code was initially using the problem files from the Bundle Adjustment in the Large library (https://grail.cs.washington.edu/projects/bal/) and I compared my performances with the Ceres solver on these problems.

I would like to know if my solver gives me good practical results in addition to the theoretical ones. I saw in your code that it is possible to recreate results from txt files in the right format. Do you know if there is a convenient way to avoid using Ceres and use my solver instead to generate these txt files ?

Ideally, I would only need to perform the bundle adjustment step and not all the previous ones. I already have a code in Julia that projects a 3D point into 2 dimensions and that undistorts the image for pinhole cameras.

My goal would be to do something along the following:

1) Generate a txt file from COLMAP that summarizes the problem before bundle adjustment has been performed

2) Solve the bundle adjustment problem in Julia

3) Format the results to match the output required by COLMAP

4) Use COLMAP to show the results.

Do you have any advice on the feasibility of this idea ?

Sincerely yours,

KENENS Antonin