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Translating coordinate frames? Or RGBDSLAM axis orientation? [closed]

asked 2012-12-02 00:27:41 -0500

updated 2014-01-28 17:14:27 -0500

ngrennan gravatar image

The short version of my question is: what's the easiest way to invert one axis of a point cloud (pointcloud2)? I.E. change every point from (x,y,z) to (x,y,-z).

My longer question is this: do I have to, or am I doing something wrong?

I'm trying to use a stereo camera with rgbdslam. It looks to me like rgbdslam uses a different axis orientation than what stereo_image_proc is putting out. The stero_image_proc wiki page has a diagram showing the point cloud reference frame as x-axis right, y-axis down, and z-axis forward. It appears that rgbdslam is x-axis left.

I've got everything running, and my point cloud coming from stero_image_proc looks correct in rviz (they are in front of the camera, like they should be) . But in rgbdslam, the points look like they're _behind_ the camera. In other words, they look like they're coming out of the screen at me rather than receding into the screen like they should.

Thanks, -Jon

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Closed for the following reason the question is answered, right answer was accepted by Jon Stephan
close date 2012-12-09 12:54:59


Hello, Jon Stephan, I'm a beginner. I want to use stereo_image_proc(call it SIP) with rgbdslam too. I can see disparity from image_view receiving topics from SIP. what should be next? rgbdslam seems listening /camera/rgb/image_rect_color & /camera/depth_registered/image_rect, but SIP don't have them

vdonkey gravatar image vdonkey  ( 2014-04-28 01:27:53 -0500 )edit

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answered 2012-12-09 05:00:31 -0500

Wow, once I found an area where the cameras picked up more points, I see that it is actually working correctly. My brain was playing tricks on me. It's really hard get the right perspective - I wish rgbdslam had a grid reference plane like RVIZ.

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Noted. Will be done in the next version.

Felix Endres gravatar image Felix Endres  ( 2012-12-09 10:22:33 -0500 )edit

Cool! Thanks!

Jon Stephan gravatar image Jon Stephan  ( 2012-12-09 11:46:52 -0500 )edit

answered 2012-12-05 08:51:04 -0500

It actually shouldn't differ from RVIZ at all. The Kinect clouds I am usually using are also "right/down/forward". What is the setting for "base_frame_name" and the frame_id of the point cloud (use "rostopic echo /<cloud_topic>/header/frame_id")?

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Yep, the base_frame_name and the frame_id match. BTW, I'm using a stereo camera, not a Kinect.

Jon Stephan gravatar image Jon Stephan  ( 2012-12-05 16:10:40 -0500 )edit

I know, but they seem to use the same coordinate system. Does rgbdslam work in principle, or are the transformations and the map wrong? How do the clouds look if saved and viewed in pcl_viewer or meshlab?

Felix Endres gravatar image Felix Endres  ( 2012-12-06 03:38:48 -0500 )edit

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Asked: 2012-12-02 00:27:41 -0500

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Last updated: Dec 09 '12