If you read through the tf tutorials, you will probably get a better idea of what is required. http://www.ros.org/wiki/tf/Tutorials/Introduction%20to%20tf Without a proper tf tree setup, it is impossible for the different nodes to know how to relate, say, a scan from the laser to a point in the odometry frame. Basically, in order to get my SLAMgmapping going with my lms291, I needed to publish a few transforms. You will need one from the base_laser to the base (base_link or whatever frame you gave it), and one from the base_link frame to the odom frame. Perhaps someone from WG can update the wiki, but I was able to get it all working after reading through the tf documentation. Some other notes about your stuff: - You are correct, you don't need scan:=scan if your laser_scan topic is already called /scan - Are you missing a publisher for /cmd_motor_state? It has a subscriber, but no type. That means nothing is publishing but something is listening, which is usually an error. If you can't figure it out from the docs, I can post the code I used to get gmapping up and running later tonight. And to answer your second post, all I needed was a static_transform_publisher to do the base_laser to base_link transform. You still need a transform from base_link to odom, and I didn't see a /tf topic at all, so no transforms were getting published. - Eric Perko wisesage5001@gmail.com eric.perko@case.edu mobilerobots.case.edu On Fri, Mar 26, 2010 at 12:28 PM, Enea Scioni wrote: > > Dear ROS-users, > I'm trying to build a map using slam_gmapping stack but without success. > I tried before to download and use the test bag file and everything works > fine. > I'm using a sick lsm200 laser and a pioneer(peoplebot) platform and for make > my bag file I used the sicktoolbox_wrapper package (sicklms), a version > modified of p2os driver wrapper and the old package teleop_base (in > particular I'm using teleop_base_keyboard to send cmd_vel commands). > > I don't know if I make a mistake when I'm trying to make a bag file, or on > the second step, when I'm trying to elaborate the bag file; anyway in the > tutorial > http://www.ros.org/wiki/slam_gmapping/Tutorials/MappingFromLoggedData I > read: > Start recording scans and transforms (note that the scan topic may vary from > robot to robot): > rosrecord -f mylaserdata /base_scan /tf > > But maybe I didn't understand the meaning of "transforms". I know that for > make a map from slam algorithm I need to save/record laserdata and odometric > data; In my case, I've the following topics: > Published topics: >  * /motor_state [p2os/MotorState] 1 publisher >  * /battery_state [pr2_msgs/BatteryState] 1 publisher >  * /rosout [roslib/Log] 3 publishers >  * /rosout_agg [roslib/Log] 1 publisher >  * /pose [nav_msgs/Odometry] 1 publisher >  * /scan [sensor_msgs/LaserScan] 1 publisher >  * /cmd_vel [geometry_msgs/Twist] 1 publisher > > Subscribed topics: >  * /time [unknown type] 4 subscribers >  * /rosout [roslib/Log] 1 subscriber >  * /cmd_vel [geometry_msgs/Twist] 1 subscriber >  * /cmd_motor_state [unknown type] 1 subscriber >  * /clock [unknown type] 4 subscribers > > So I recorded scan and pose messagges in this way (note: I don't have a tf > topic message) : > record -f mylaserdata /scan /pose > > After, When I'm try to make a map, I ran: > rosrun gmapping  slam_gmapping scan:=scan > (scan:=scan it's not necessary I think) > and I used the rosplay command as well: > rosplay mylaserdata-.bag > > After this, I received form slam_gmapping command this warning: > [ WARN] 1269617084.120287000: MessageFilter [target=/odom ]: Dropped 100.00% > of messages so far. Please turn the [ros.gmapping.message_notifier] > rosconsole logger to DEBUG for more information. > > The warning it's correct (I send a odom messages) and it doesn't receive > information from scanner data, like in the test.bag example. > So I suppose that something in topic name is wrong, or better, the > slam_gmapping expects a tf message, as described in the ros wiki > http://www.ros.org/wiki/gmapping 5.1 Subscribed topics, where I read > "Transforms necessary to relate frames for laser, base, and odometry (see > below) " but "below" I didn't find information necessary for understand how > convert odometric message in a tf message and why I need to to this... > > Anybody can help me? > Thank You! > > Regards, > Enea Scioni > > -- > View this message in context: http://n3.nabble.com/slam-gmapping-messages-problem-tp676863p676863.html > Sent from the ROS-Users mailing list archive at Nabble.com. > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. 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