hi Laura,

Before we dig into the data, can you verify that your odometry data is
reasonable?

Using rviz:
* set the fixed frame to 'odom' (or whatever your odometry frame is)
* increase the decay time on the laser data (e.g., to 60 seconds)
* using a joystick, slowly rotate the robot in place, and also drive
it around a little
If your odometry data is good, you should see a crude "map" be
constructed from the accumulated laser scans. Some amount of error is
expected, but the scans should be visibly coherent. If they're not,
then you should look at how you're computing the odom->base_link (or
equivalent) transform.

	brian.

On Mon, Sep 20, 2010 at 9:00 PM, laura galindez <laurago894@gmail.com> wrote:
> Hi!
>
> I have been trying to create a map from Sick lms200 laser scans using
> slam_gmapping node. However the laser scans overlap and I end up with an
> illegible map. My launch file looks like the following:
>
> <launch>
>   <master auto="start"/>
>   <!-- Static transform for base of scanner to robot base -->
>   <node pkg="tf" type="static_transform_publisher" name="tf_static"
> args="0.1 0 0.2 0 0 0 base_link base_scan 20" />
>
>   <!-- Sicktoolbox_wrapper node -->
>   <node name="SickWrapper_client" pkg="sscrovers_laser_pub" type="sicklms2"
> />
>
>   <!-- Modified version of ROSARIA client with a safe exit on interruption
> -->
>   <node name="ROSARIA_client" pkg="ROSARIA" type="RosAria"/>
>
>   <!-- Teleoperation program for RosAria node-->
>   <node name="teleop" pkg="ROSARIA" type="teleop"/>
>
>   <node name="Gmapping" pkg="gmapping" type="slam_gmapping"
> args="scan:=base_scan"/>
>   <param name="map_update_interval" value="1" />
>
> </launch>
>
> I am guessing the problem has to do either with the odometry or with the
> gmapping node. Here is a picture of the map I created:
> http://yfrog.com/5ywhdp
>
> And here is the bag file of the logged data:
> http://www.mediafire.com/?uw4jm8ffm67tbc2.
>
> I also wanted to mention that gmapping sometimes generates warnings
> concerning the cache time and TF_OLD_DATA. I am not sure if these warnings
> are in direct relation with my problem.
>
>
> Thank you for your help.
>
> Regards!
>
> Laura
>
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