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Kinect laser range - strange values.

asked 2012-04-07 06:53:40 -0500

anonymous user


updated 2016-10-24 09:02:37 -0500

ngrennan gravatar image

I'm trying to get several value from my turtlebot's kinect laser (specifically the left-most and right-most laser ranges). I'm currently reading the sensor_msgs/LaserScan ranges array for those values. If I cover the laser with my hand, the values are read as 11 for some reason - can anyone explain this? Also, it seems like the laser doesn't fire as far as it possibly can - if I put the turtlebot in the middle of a room, the range values reported are also 11 (most of the time - if I put an object a few feet in front of the turtlebot, some of the ranges change. Is there a way to extend or set the kinect's laser range? Could someone clear this up for me?

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answered 2013-02-11 01:43:43 -0500

JBuesch gravatar image

updated 2013-02-11 01:44:30 -0500

The reason is that Kinect doesn't use single laser beams to get the distance, but a laser image, that is projected into the room. A camera slightly apart from this laser image source 'sees' this image from a slightly different angle and can hence calculate the distances. To do this successfully, objects must have a minimum distance to the Kinect - usually 60cm.

That the sensor reports 11m, when you cover it with your hand, means it has no reasonable values to offer and reports invalid ones. Have a look at range_max value. It will pretty sure be 10m in your case.

If that's the case, everything is ok. Although there should be reasonable values in the laser array, if distances in front of the camera range from 60cm - 6m.

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answered 2013-02-11 02:42:19 -0500

By default for kinect the angle sweep is from -90 to +90 but it only works for -28 to +28 therefore most of the value is around 11.0 if ur max_range_value is set to 10. Try using demo gmapping program for turtlebot and u'll get better incite about laser values from the map that is created.

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Asked: 2012-04-07 06:53:40 -0500

Seen: 877 times

Last updated: Feb 11 '13