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GMAPPING: How to mark 'out of range' laserscan as free-space

asked 2015-12-17 04:33:54 -0500

Alex1209 gravatar image

I'm using a SICK TIM 300 Laserscanner with the gmapping node to create a Map. But whenever the Laserscanner can not see an obstacle at a certain angle (because the obstacles are out of range), gmapping marks these areas as 'unknown'. But the Laserscanner not seeing anything at a certain angle, means there is no obstacle within the measuring-range (in my case: 4m). As a result gmapping should mark these areas as free.

How can I solve this problem?

I'm using Ubuntu 12.04 with ROS hydro. The Laserscanner marks these 'out-of-range'-areas as 'distance = 0m', the header from the /scan - message tells that the minimum distance is 0.05m.

Thanks for your help.

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answered 2015-12-17 05:25:00 -0500

If you take a look at the gmapping page there're two parameters called maxUrange and maxRange. I quote: "If regions with no obstacles within the range of the sensor should appear as free space in the map, set maxUrange < maximum range of the real sensor <= maxRange".

So, if you want that region appears as free space, you have to set your maxUrange under the maximum range of the real sensor (which is the maxRangeparameter).

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Thank you very much :D It's that easy. Now the map looks way better.

Alex1209 gravatar image Alex1209  ( 2015-12-17 16:01:01 -0500 )edit

what is the unit of maxUrange and max range?

aarontan gravatar image aarontan  ( 2018-05-19 14:51:01 -0500 )edit

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Asked: 2015-12-17 04:33:54 -0500

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Last updated: Dec 17 '15