Exporting a map to the .nvm format

Overview

The export_map tool is used to export a map from an Astrobee .map file in Protobuf format to the plain text .nvm file format, which is a format used by various SfM packages, and can be exported by Theia.

This tool does not export the camera intrinsics and image descriptors, but only the list of images, the position and orientation of each camera, and the interest point matches (tracks).

The obtained .nvm file can be imported back with the Importing a map in .nvm format tool.

The interest points saved to the nvm file are offset relative to the optical center, per the NVM format convention. To not do that, use the -no_shift option. The import_map tool then must use the same option to import back such an .nvm file.

Example:

$HOME/astrobee/devel/lib/sparse_mapping/export_map  \
  -input_map input.map                              \
  -output_map output.nvm

Command line options:

-input_map <string (default="")> Input sparse map file, in Astrobee's protobuf format, with .map extension. -output_map <string (default="")> Output sparse map in NVM format. -no_shift Save the features without shifting them relative to the optical center. That makes visualizing them easier.