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Dealing with transparent objects, combining two Xtion.

asked 2016-07-25 05:55:26 -0600

necro gravatar image

updated 2016-07-25 05:55:40 -0600


I'm trying to make 3D map of my office with XtionPRO Live, the biggest problem i met so far is dealing with transparent/aborbing objects etc. I tried to avoid them but they still reflects (windows, glass doors) and i got random erros on my map (like inclined in the middle of room). Other things like glasses or bottles are hard to avoid. I couldn't find any solution and it's seems to be impossible to solve problem due to Xtion sensor is using IR.
The only thing i found is publication about combining two Xtions ( ). I'm new to RoS/mapping and publication I found is too complex for me to implementation. I understand main assumption but I'm not sure how to prepare it and use with RTAB-map.
I am able to get second Xtion/Kinect but how should i calibrate them? Earlier i used ( ) but in that way i can pass mono calibration for sensors separately, how can i combine them? Is there any way to achieve goal with available packages? Is there any other solutions to deal with objects like that in RTAB-map?

Thanks for answers.

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I don't to which extent you can integrate it in RTAB map but sonars are the solution to transparent objects.

Mehdi. gravatar image Mehdi.  ( 2016-07-25 10:07:27 -0600 )edit

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answered 2016-07-26 07:48:19 -0600

matlabbe gravatar image

Reflective and transparent surfaces are very challenging for mapping approaches. For the two Xtions approach you refer, it is a stereo setup with IR images. You may use stereo calibration tutorial to calibrate the Xions with each other. Well, you may have to hide the IR pattern when calibrating. On runtime, you may use stereo_image_proc to generate the disparity image. Be aware that this package may assume horizontal stereo, so you may have to rotate the images/camera_info, then rotate back the output disparity. By converting the disparity to depth (rtabmap_ros/disparity_to_depth) and left IR image to Gray scale, you could use rgb-d interface of rtabmap.

However, some surfaces are just very difficult to detect with vision/laser, just think about a mirror or clean glass...

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Thanks for Your involvement! Already I'm waiting for second Xtion and in meantime I got ZED camera to play with. ZED Wrapper got this file, so why i need to run rosrun tf static_transform_publisher? Seems very similar for me what's the diff

necro gravatar image necro  ( 2016-07-26 08:10:19 -0600 )edit

Oh, that commit (June 21) modified the TF frames of the ZED. They are also starting their own odometry with the camera driver. The tutorial should be updated.

matlabbe gravatar image matlabbe  ( 2016-07-26 08:39:12 -0600 )edit

So what should i do? Without line from Your tutorial i got:

odometry: Could not get transform from camera_link to /zed_tracked_frame (stamp=1469541052.943110) after 0.200000 seconds ("wait_for_transform_duration"=0.200000)!

After running your line i can successfully see rtabmap gui.

necro gravatar image necro  ( 2016-07-26 08:53:23 -0600 )edit

Other thing is that my clouds are "waved". My ZED is uncalibrated in ROS but i read that it's pre-calibrated and I don't need to do anything. Here is my screenshot:
The wall on right isn't straight. Does that camera need more clouds to give depth?

necro gravatar image necro  ( 2016-07-26 09:02:44 -0600 )edit

Using ZED Depth Viewer with this tool I could obtain pointclouds straight from the camera and it's waved too. Other thing is that I can see only one cloud, because tool ZEDfu for mapping is still unreleased for Linux. I will try to check it under Windows and see if assembling will straighten image.

necro gravatar image necro  ( 2016-07-27 01:56:19 -0600 )edit

You may set a maximum cloud depth to filter far waved clouds. See also "To have similar results than ZedFu..." section in .

matlabbe gravatar image matlabbe  ( 2016-07-27 08:41:47 -0600 )edit

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Asked: 2016-07-25 05:55:26 -0600

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Last updated: Jul 26 '16