The maplab framework now supports the addition of external visual features. This is done through the interfaces defined in this message.
To notify the maplab node to expect external features, one has to modify the calibration file to add a new type of external features sensor. An example of how this is done for the HITLI datasets is shown here.
In parallel with maplab one can then run the external features detection module which is implemented here. There are example launch files for various supported feature types: