Re: Scan (app) > import/optimize (PC) > export
Posted by matlabbe on
URL: http://official-rtab-map-forum.206.s1.nabble.com/Scan-app-import-optimize-PC-export-tp2634p2824.html
Hi,
Thx for sharing the database, it is easier to show an example. To add manually a loop closure, this can be done with Database Viewer. Here is an example. Select two images, here 6 and 712. I also changed Feature Type used (SIFT instead of BRIEF) and minimum required (25->15), then pressed "Add" in Constraints View:
I received this error:
To resolve this, instead of increasing the "RGBD/OptimizeMaxError", I rejected the loop closure 413->415. I tried again and another link caused problem, so I rejected it too. The third try worked (we can see on the right the two point clouds correctly superposed):
Another approach
As shown by the error messages above, some loop closures are weak, because of the default GFTT/BRIEF features used that may be not suitable for this kind of environment. I reprocessed the database as source in RTAB-Map like in the above posts, but with changing Vocabulary type to SURF, then mapped again. After the run, I clicked Tools->Post-processing... and added more loop closures. The loop closure above is automatically found, so no need to manually modify the database. Here is a comparison between Tango odometry and with loop closures of the three traversals over the same box:
Other views:
As shown in the last screenshot, there are errors at the other side of the map, where there is no loop closure possible. As shown below, maybe having another "anchor" at the bottom of the slope (bottom left of the screenshot below) to find loop closures between traversals could help to reduce these errors.
cheers,
Mathieu
URL: http://official-rtab-map-forum.206.s1.nabble.com/Scan-app-import-optimize-PC-export-tp2634p2824.html
Hi,
Thx for sharing the database, it is easier to show an example. To add manually a loop closure, this can be done with Database Viewer. Here is an example. Select two images, here 6 and 712. I also changed Feature Type used (SIFT instead of BRIEF) and minimum required (25->15), then pressed "Add" in Constraints View:
I received this error:
To resolve this, instead of increasing the "RGBD/OptimizeMaxError", I rejected the loop closure 413->415. I tried again and another link caused problem, so I rejected it too. The third try worked (we can see on the right the two point clouds correctly superposed):
Another approach
As shown by the error messages above, some loop closures are weak, because of the default GFTT/BRIEF features used that may be not suitable for this kind of environment. I reprocessed the database as source in RTAB-Map like in the above posts, but with changing Vocabulary type to SURF, then mapped again. After the run, I clicked Tools->Post-processing... and added more loop closures. The loop closure above is automatically found, so no need to manually modify the database. Here is a comparison between Tango odometry and with loop closures of the three traversals over the same box:
Other views:
As shown in the last screenshot, there are errors at the other side of the map, where there is no loop closure possible. As shown below, maybe having another "anchor" at the bottom of the slope (bottom left of the screenshot below) to find loop closures between traversals could help to reduce these errors.
cheers,
Mathieu
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