16.51. parse_match_file.py

This tool reads an ASP match file in binary format as written by ipmatch (Section 16.36), bundle_adjust (Section 16.5), or stereo (Section 19), and writes it as a text file, with each line having an interest point and other associated information. The first half of the file has interest points for the left image, and the second half has corresponding points in the right image.

It is assumed that the version of Python in the path has the numpy and argparse packages installed and that parse_match_file.py is in the path.

Example:

python $(which parse_match_file.py) run/run-left__right.match \
  run/run-matches.txt

The reverse of this operation can be performed as:

python $(which parse_match_file.py) -rev run/run-matches.txt \
  run/run-left__right.match

Note that the second invocation does not result in exactly the same match file as the original one, as the descriptors for each interest point are ignored on reading the text file. In practice that is not important, as descriptors are needed only when the interest point matches are created.

Other functionality which may be used to understand interest points is the option --save-cnet-as-csv in bundle_adjust which saves the interest point matches in the plain text format used by ground control points (GCP). This tool also saves a file named final_residuals_pointmap.csv in the output directory which has for each set of matching interest points the triangulated world position and the error of re-projecting such a point back in the cameras (Section 16.5).