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According to REP 103 (http://www.ros.org/reps/rep-0103.html) units in ROS should always be SI units. In this case, linearUpdate is in meters, as it is a distance traveled by the robot.
Setting this value lower will cause gmapping to update more frequently (say, every 0.25 or 0.5m of travel). Setting it to a higher number means less frequent updates. Less frequent updates are nice for reducing the memory/processor usage, however, if you have a short range laser or very poor odometry, it may cause the scan matcher to fail if the robot goes too far between updates.
Thanks Fergs for your reply. In slam_gmapping, linearUpdate is 1 by default. Do it mean it updates global map after every 1m travel? Does it mean it ignore laserScan which are saved before each 1 meter?
Thats exactly what it means. Once you move 1m, gmapping will use that laserscan in the map building process. If you are using a 30m laser like the UTM30 on the PR2, 1m is fine. If you're using something like a kinect or smaller Hokuyo laser, 0.25 or 0.5 is pretty common.
Asked: 2013-11-11 13:48:13 -0500
Seen: 435 times
Last updated: Nov 11 '13
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