Using an XV11 lidar and calibrated odometry, I am able to build a good quality map using both hector_mapping (using scan results only) and pure odometry (using odometry only).
However, I am unable to get a good map using gmapping (which combines scan results and odometry).
***Odometry:***
My robot has odometry that passes the tests listed in the [navigation tuning guide](http://wiki.ros.org/navigation/Tutorials/Navigation%20Tuning%20Guide) - linear translation is perfect, rotation error seems to be reasonable as well.
***Lidar:***
Additionally, it is using an XV11 lidar as laser scanner, with the xv_11_laser_driver package.
***Bagfile:***
I've recorded a short bag file with /odom, /tf and /scan topics, using following command:
``rosbag record -O second_data /scan /tf /odom``
I then compressed the bagfile (``rosbag compress second_data.bag``), and put it available [here](https://github.com/KristofRobot/frobo/blob/master/bagfile/second_data.bag).
***Map results:***
If I transform this bag file into a map using **hector_mapping**, the result looks perfect: 
EDIT: Here are links to the hector_mapping generated [pgm](https://raw.githubusercontent.com/KristofRobot/frobo/master/bagfile/hector.pgm) and [yaml](https://raw.githubusercontent.com/KristofRobot/frobo/master/bagfile/hector.yaml) files.
Moreover, if I simply display the laserscan results in **rviz in the /odom** frame, with an infinite decay time, I get a very nice map as well:
Now, when I try to run this through **gmapping**, the map looks very poor:
EDIT: Here are links to the gmapping generated [pgm](https://raw.githubusercontent.com/KristofRobot/frobo/master/bagfile/gmapping.pgm) and [yaml](https://raw.githubusercontent.com/KristofRobot/frobo/master/bagfile/gmapping.yaml) files.
***Commands:***
To generate the gmapping map, I used:
rosparam set use_sim_time true
rosparam set slam_gmapping/delta 0.1 #set resolution to 0.1
rosrun gmapping slam_gmapping scan:=scan
rosbag play second_data.bag --clock
rosrun map_server map_saver
To generate the hector_mapping map, I used:
rosparam set use_sim_time true
roslaunch hector_mapping mapping_default.launch
rosbag play second_data.bag --clock
rosrun map_server map_saver
Launch file is available [here](https://raw.githubusercontent.com/KristofRobot/frobo/master/bagfile/mapping_default.launch).
PDF graph of tf tree is available [here](https://github.com/KristofRobot/frobo/raw/master/bagfile/frames.pdf).
***Question:***
How come gmapping gives such poor results, compared to the two other approaches?
Any suggestions to improve the gmapping results would be much appreciated.
Thank you,
Kristof
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