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Is gmapping possible with tilted kinect using turtlebot ?

asked 2013-08-24 12:07:16 -0600

sudhanshu_mittal gravatar image

updated 2016-10-24 08:35:14 -0600

ngrennan gravatar image

I am trying to use turtlebot for both gmapping for autonomous exploration as well as capture point cloud of ground. We know in Turtlebot, gmapping using kinect is implemented by the package "turtlebot_navagation" along with "turltebot_bringup". The gmap is constructed using the laser_scan data, which is actually fetched from the point_cloud data by selecting the particular plane of points. When we mount the turtlebot at greater height with zero tilt/Pitch angle, the point cloud of nearby ground upto first 2m is not observed. So my question is : IS it possible to construct a gmap with the downward tilted kinect ? I mean selecting a different plane of points (at some angle) from point_cloud to use it for laser scan ?

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answered 2013-08-25 15:52:40 -0600

jorge gravatar image

Fast answer is "no", sorry. Turtlebot uses pointcloud_to_laserscan (groovy) or depthimage_to_laserscan (hydro). Afaik, both assumes a horizontally pointing kinect. It shouldn't be hard to modify them to allow tilted cameras, but then you will find that both gmapping and amcl assume (again afaik) horizontally aligned laser scans.

Also, xxxxx_to_lasercan just takes an horizontal "slize" of the camera view centered on the optical axis. You can change how high this slice is, but everything outside it will not be present in the laser scan.

Now, some good news: all I said holds for 2D mapping and localization, but not for obstacles avoidance nor 3D mapping. So as long as you use your 2D map just for localization, all you need is that both amcl and gmapping "see" the same. Obstacles above or below the kinect will not be in the map, but for this you have move_base's obstacle avoidance, who can use full pointclouds with any orientation. This is not the default configuration of turtlebot, but you can easily change move_base configuration files to do so.

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Asked: 2013-08-24 12:07:16 -0600

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Last updated: Aug 25 '13