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Need some help with Mapping and Azure Kinect

asked 2020-11-23 09:38:45 -0500

Janus gravatar image


i am a newbie, a first time user of RTAB-MAP and ROS. But after days of trouble shooting and reading forum messages a think it's time to just ask.

First of all, i think it is good to explain my goal. I want to make as good as (it gets with a Azure Kinect) possible pointclouds, from rooms/houses/buildings and maybe some scans of accutools.

What i want from that is:

  1. 2d plans (with angles between walls) and height.
  2. Measure some random things (at home) like windows (frames).
  3. And if thats working allright, use software (with recognition) to make a 3d file/project from the cloudpoints (for VR and or designing and building cabinets)

I know that ROS and RTAB-Map is more designed for robot navigation, but if all goes well, i want to build a robot for scanning/mapping. Number one priority for now, is quality of the pointcloud.

So a couple of questions and a problem:

  1. The most important one: can RTAB-Map deliver good enough pointclouds for my goals? (icm Azure Kinect)
  2. What are the device specific settings that i can alter for best results of points? Maybe for the kinect the field of view, min and max distance because of distortion, or is that all (better) handled by ROS/RTAB-MAP?
  3. If nr. 1 is Yes; what is the best way to do this. Set decimation of the points as low as possible while scanning, or do that afterwards? I also could not find a clear answer if RTAB-Map saves all info to make an as good as possible pointcloud, or is a lot of information gone after decimation and filtering?

I believe i saw all photos from a scan, but depth images where in another format as extracted from Azure Recorder's mkv. So does it contain all info, and if ROS or RTAB-Map isnt build / cannot produce best possible pointcloud, can other software handle this format depth images?

Till now i can only produce i pointcloud from what i believe is always the last viewing point. First i thought it had to do with not loading all pointclouds. But now i think it has to do with not getting any loopclosures. I filmed it with hand so i think that has to do with to fast movement, and i also did sometimes point it upwards for filming the cealing. But even then, i think there are long enough parts that should have more info for a larger pointcloud than just the end scene (last picture). I dont mind my pc is calculating for days to get it. Just curious of that is possible, or if i have to film it more slowly and carefully.

In another forum question i saw that rtab-map is saving/using only 1 fps for its map and also that 30 fps is way to fast for it. Is that true with all graphicscards? (maybe only an answer on that particular question) Because i ordered an Jetson AGX to ... (more)

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You appear to have posted a duplicate of your own question. Could you please check #q366175 and delete either that one or this one? Thanks.

gvdhoorn gravatar image gvdhoorn  ( 2020-11-23 10:06:17 -0500 )edit

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answered 2020-11-24 16:47:02 -0500

matlabbe gravatar image

It will be easier to answer to question if you have a database to share on some tests you tried. The 1 FPS is the update of the map, not the odometry. It is recommended to run odometry at 30 FPS or more. The 1 FPS is because unless you move very fast, we don't need to keep all 30 HZ frames (which would have a lot of overlap anyway). With Kinect for Azure, I've seen better visual odometry using IR image + Depth image, which has a larger field of view than the RGB camera. It is also possible to do only ICP odometry too, which gives quite accurate results like in this post. The point cloud can be regenerated at the the resolution you want as rtabmap keeps all raw data. For detecting corners and make a nice 2D floorplan from the point cloud, rtabmap cannot do that (only occupancy grids but it seems not what you want to do).

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Thanks for your answer. How should i share the db's? Because i see a lot of "rosbag's" on the forums but don't know how to generate these yet. So if thats not necessary i will upload the normal db.

In that post the depth setting is binned. Is that possible even if i have recorded the mkv unbinned, so is all info still there in mkv? In my test with rtabmap and a mkv it looked like all changes like fps and resolution where ignored which makes sense to me because starting the camera in an other resolution is different than transcoding it. So my guess would be that all settings will be the same the way it is recorded, also binned and unbinned, but i am not sure of that.

Also you have 720p as RGB resolution, do you think that is the max resolution that ...(more)

Janus gravatar image Janus  ( 2020-11-25 06:20:03 -0500 )edit

I didn't test a lot MKV format with some other API options when reading it, but I guess the output format would be the same than the one recorded. It can be also a rosbag, but you must also provide the launch file you used. The database is faster to debug with for common errors. If the errors are coming from visual odometry, then a rosbag will be required (or the MKV file).

matlabbe gravatar image matlabbe  ( 2020-11-25 09:43:49 -0500 )edit

I finally have some time for trouble shooting again. Have all databases, mkv's and the used launch file in a folder and ready to share. Can i PM the link and password to you? The fabric has a "no video" policy, i did get an exception because it was for measuring, but i rather share it with only the people that help trouble shoot.

I am also compiling RTABMap from source with k4a gtsam and libpointmatcher enabled as you mentioned in the post you shared, so hopefully i can test that setup tomorrow.

Janus gravatar image Janus  ( 2020-12-02 16:46:44 -0500 )edit

my email is the same than my username here, at gmail.

matlabbe gravatar image matlabbe  ( 2020-12-10 12:31:55 -0500 )edit

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Last updated: Nov 24 '20