hector_slam contains ROS packages related to performing SLAM in unstructed environments like those encountered in the Urban Search and Rescue (USAR) scenarios of the RoboCup Rescue competition.
if you check this line, it uses gridMap.getCellLength() function that returns cell length in millimeter.
but, according to message definition, it should be meter, not millimeter.
So I think it should be corrected as below
https://github.com/tu-darmstadt-ros-pkg/hector_slam/blob/b7d19bfee3c2848d611e8da142445b896790d7fb/hector_mapping/src/HectorMappingRos.cpp#L547
if you check this line, it uses gridMap.getCellLength() function that returns cell length in millimeter. but, according to message definition, it should be meter, not millimeter. So I think it should be corrected as below
I created pull request, so check it please.