Please help me.. there are too many obstacles in the graph view.

[kuacboss]

I am a beginner. I mapped the school hallway and it looks like this even though there are no obstacles. Does this black color represent matched feature points? If so, is there a way to prevent me from recognizing the ceiling or floor features as obstacles (black)?

[matlabbe]

you can look at Grid/ parameters:

rtabmap --params | grep Grid/
[...]
Param: Grid/MaxObstacleHeight = "0.0"                      [Maximum obstacles height (0=disabled).]

So to filter ceiling, you could add --Grid/MaxObstacleHeight 1.5 to rtabmap arguments.
By default the floor should not be detected as obstacle. How are you mapping? in 2D, 3D? on a robot?

[kuacboss]

I am using realsense 455 for my robot. The biggest problem is that, as in other maps, when you visit the same place on a 2D map, the previous map information is erased and a black point cloud appears, ruining the map.

[matlabbe]

Can you share the database?

If stereo data gets too noisy, you may just use a simple thresholding of the floor by turning off normals segmentation (Grid/NormalsSegmentation=false) and set Grid/MaxGroundHeight to 0.1 m for example.