Hi, I'm a beginner trying to build a map using this tutorial. There is one change I'd like to make: build in real time. I figured that slam_gmapping node would have to take data not from .bag file, but directly from topics /scan and /tf. My first question is: is my thinking correct?

If so, how should look rosrun command? In tutorial it's "rosrun gmapping slamgmapping scan:=basescan". I've tried this one, but gmapping does not work: there's a following warning:

MessageFilter [target=/odom ]: Dropped 100.00% of messages so far. Please turn the [ros.gmapping.message_notifier] rosconsole logger to DEBUG for more information

and there is no data on my /map topic. I guess it's because I didn't point to odometry topic anywhere. So my second question is: how to make it work? Things I've tried:

• Execute command "rosrun gmapping slamgmapping scan:/robot/scan _odomframe:=odom_combined"
• This solution: "rosrun gmapping slamgmapping scan:=/robot/scan _odomframe:=/robot/odom"
• This solution with running statictransformpublisher

None of these worked. My tf tree:

/robot/odom -> /robot/baselink -> /robot/baselaser_link