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What are LaserScan intensities?

asked 2015-07-19 21:30:51 -0600

nodge gravatar image

updated 2015-07-20 03:59:07 -0600

mgruhler gravatar image

Hi, the LaserScan ROS message is

Header header
float32 angle_min        # start angle of the scan [rad] 
float32 angle_max        # end angle of the scan [rad]
float32 angle_increment  # angular distance between measurements [rad]
float32 time_increment   # time between measurements [seconds] 
float32 scan_time        # time between scans [seconds]
float32 range_min        # minimum range value [m] 
float32 range_max        # maximum range value [m]
float32[] ranges         # range data [m] (Note: values < range_min or > range_max should be discarded)
float32[] intensities    # intensity data [device-specific units]

What are the intensities?



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answered 2015-07-20 02:20:54 -0600

mgruhler gravatar image

The intensities field should contain the measured intensity (i.e. brightness) of the reflected laser beams. This is, however, device specific and thus you cannot really make any assumptions about the values. In general, the higher the value, the brighter the reflected laser beam.

You can use the intensities to make some assumptions about the properties of the scanned material. E.g. it is used to detect reflectors and reflector tape, as there the intensity of the reflected beam is, in general, higher than from other material.

E.g. the Hokyuo Laser scanner provides full intensities, whereas the Sick S300 only provides information about whether it detects a Reflector Tape (0 if none, not 0 if a reflector tape detected).

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Asked: 2015-07-19 21:30:51 -0600

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Last updated: Jul 20 '15