What KP matches does the databaseviewer display?

[mattiasmar]

Does the databaseviewer display keypoint matches found during creation of the db file or does it recalculate the matches on its own?

[matlabbe]

They are the keypoints saved in the database. It can re-extract them on specific post processing actions (when trying different parameters tham when the db was created).

[matlabbe]

No, individual post-processing actions cannot be saved back in database. THe workflow I use is to try different parameters with rtabmap-databaseViewer on some frames, then when satisfied, reprocess the whole database with those parameters (example here by increasing the number of features used for loop closure detection):

rtabmap-reprocess --Kp/MaxFeatures 800 rtabmap.db output.db

[mattiasmar]

My previous question was about how one can "try different parameters with rtabmap-databaseViewer on some frames".
I see a window ("info") that shows all the parameters that were used:

I don't see where I can edit one or more parameters and then re-execute keypoint detection (and matching). Where do I do that?

[mattiasmar]

...you probably meant the "Add" button under in the "Constraint view" pane.

[mattiasmar]

But where do one change parameters before clicking on Add? For example keypoint threshold, match threshold, MaxFeatures, where can I edit those in the databaseviewer?

[matlabbe]

Open the "Core Parameters" view in databaseviewer. To re-extract features, check parameter RGBD/LoopClosureReextractFeatures

Yes, use Add button to add a new loop closure between two selected frames.