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From 3D to 2D - where to start?

asked 2016-06-08 07:06:30 -0600

FTUB gravatar image

I need to convert some 3D-maps made with rgbdslam/rtabmap-slam into 2D gridmaps, but really don't know where to start. Can someone please answer me some question to get this done?

1.) rgbdslam: can save octomaps over GUI but the file extension of saved files is pcd instead of bt/ot. Why?

2.) read a lot about saving maps while processing with "rosrun map_server map_saver -f filename". Tried that while rgbdslam/rtabmap where running - response is always: "waiting for map". Do I have to install octomap_server into the same workspace as both slams? And if thats the solution, will I finally have a 2D gridmap by running this command?

As you can see on my questions, I'm a newbie. I know this question has been asked and answered multiple times before though i was not able to make it. I would really appreciate it if someone could help me out.


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rtabmap has proj_map output topic, which is the 3D point cloud projected on the ground: rosrun map_server map_saver map:=/rtabmap/proj_map

matlabbe gravatar image matlabbe  ( 2016-06-08 08:13:36 -0600 )edit

Thanks for your reply! Unfortunately still "waiting for map"... rtabmap is running and recording, both are "sourced" from the same setup files.

FTUB gravatar image FTUB  ( 2016-06-08 10:29:02 -0600 )edit

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answered 2016-06-08 07:42:46 -0600

1) That's a bug, I thought I already fixed. The workaround is easy though: Just change the extension to .ot in the save dialog.

2) octomap_server has some capability to downproject the map. See the description of the map topic on its wiki page. Should be easy to subscribe to this topic and save the map. Maybe there is even an existing node for that.

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Thanks for the fast reply Felix! Thats exactly my problem, how do I subscribe to a (/the map) topic? I've read this a bunch of times before but haven't found a detailed explanation yet. Do you mind to tell me how to continue with this (or the keywords to look for in ros tutorials)?

FTUB gravatar image FTUB  ( 2016-06-08 10:23:52 -0600 )edit

I recommend you to read the tutorials 6, 10, and 11 or 12. Anything more specific depends on how you want to use the map.

Felix Endres gravatar image Felix Endres  ( 2016-06-08 11:16:22 -0600 )edit

Ok, done. map_saver subscribes now from topic /projected_map, octomap_server provides the data, rqt_graph looks good. But it seems octomap_server doesn't subscribe from rgbdslam: I remapped topic with <remap from="cloud_in" to="/rgbdslam/batch_clouds"/>, but when I press ...

FTUB gravatar image FTUB  ( 2016-06-13 10:36:09 -0600 )edit

... "send model" in gui, terminal responds with: "no Subscribers, sending of clouds cancelled". rqt_graph only shows one arrow with "tf" headline and that is not a topic, right? what do I miss?

FTUB gravatar image FTUB  ( 2016-06-13 10:39:16 -0600 )edit

The remap seems correct. Could you post the rqt_graph image? Have you had success saving to file, when specifiying the extension .ot?

Felix Endres gravatar image Felix Endres  ( 2016-06-14 03:41:38 -0600 )edit

rqt-graph: saving octomap with .ot extension works fine. We firstly started rgbdslam+octomap_server+map_saver, recorded an octomap, send model. After sending the model, this error message occurs (from octomap_server): ...

FTUB gravatar image FTUB  ( 2016-06-14 05:26:00 -0600 )edit

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

FTUB gravatar image FTUB  ( 2016-06-14 05:26:09 -0600 )edit

Hm, I don't see where you would have done something wrong. Actually rgbdslam should send the transformations with the clouds, but maybe they are too old for the octomap server to use? I never had this problem though...

Felix Endres gravatar image Felix Endres  ( 2016-06-14 11:55:50 -0600 )edit

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Asked: 2016-06-08 07:06:30 -0600

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Last updated: Jun 27 '16