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