There's a basic implementation here: https://code.google.com/p/rosjava/source/browse/google_map_transport/src/main/java/com/google/google_map_transport/MapTransport.java?repo=google In this case, I'm also scaling the image if necessary. On Mon, Mar 25, 2013 at 3:48 PM, Dereck Wonnacott wrote: > Damon, > > Well, that just makes all kinds of sense, would you mind sharing your > implementation details? :) > > > I wonder if we could support this in a generic manor by adding an 'encoding' > to nav_msgs/MapMetaData +1 > then nav_msgs/OccupancyGrid's data[] could be encoded in a wide number of > formats. Perhaps we can use openCV to do the encoding/Decoding as well. > > This would break backwards compatibility, but it seems like the right way to > go since adding the encode/decode should be a trivial fix for dependent > packages to come up to date.... :/ +1 > ~Dereck > > > > “The greater danger for most of us lies not in setting our aim too high and > falling short; but in setting our aim too low, and achieving our mark.” - > Michelangelo > > > On Mon, Mar 25, 2013 at 5:25 AM, Damon Kohler > wrote: >> >> Rather than dealing with deltas, I've been simply PNG compressing the >> occupancy grid data. That helps a lot. >> >> On Sun, Mar 24, 2013 at 8:58 PM, David Lu!! wrote: >> > This is useful discussion topic. Some people have already been exploring >> > it >> > with the OccupancyGridUpdate message >> > >> > (http://ros.org/doc/groovy/api/map_msgs/html/msg/OccupancyGridUpdate.html) >> > in particular Stéphane Magnenat. There was a REP partially related to >> > this >> > topic >> > >> > (https://github.com/stephanemagnenat/rep/blob/91dc02f8f2a82c5ef4820d2fc9f0f6d1fd1d0c20/rep-0129.rst) >> > but I'm not sure what the final status of it was. >> > >> > >> > >> > >> > On Sun, Mar 24, 2013 at 8:59 AM, Dereck Wonnacott >> > wrote: >> >> >> >> ROS users, >> >> >> >> I had an idea for improving map topics and would like to open it up for >> >> discussion and get some feedback on the idea. >> >> >> >> Problem: I like to run rviz for my mobile robot on a different computer >> >> than my robot for obvious reasons, but when gmapping maps get large >> >> they >> >> tend to saturate the network. >> >> >> >> Idea: Reduce the required bandwidth by publishing map deltas rather >> >> than >> >> full maps. >> >> >> >> Implementation details: The /map topic would publish the full map and >> >> latch that message for new subscribers. >> >> >> >> The /map-updates topic could then publish a hash of the map being >> >> published on /map and a list of changes required to bring that map up >> >> to >> >> date. >> >> >> >> When the change list size exceeds some threshold, it can publish and >> >> latch >> >> a new map on the /map topic. This will cause /map-updates to have a new >> >> hash >> >> and clear the change list >> >> >> >> The full map could be published on /map-full for backwards >> >> compatibility >> >> with older nodes. >> >> >> >> Suggestions and feedback on the idea greatly appreciated. :) >> >> >> >> ~Dereck Wonnacott >> >> Michigan Tech Robotics Lab >> >> >> >> >> >> “The greater danger for most of us lies not in setting our aim too high >> >> and falling short; but in setting our aim too low, and achieving our >> >> mark.” >> >> - Michelangelo >> >> >> >> _______________________________________________ >> >> ros-users mailing list >> >> ros-users@code.ros.org >> >> https://code.ros.org/mailman/listinfo/ros-users >> >> >> > >> > >> > _______________________________________________ >> > ros-users mailing list >> > ros-users@code.ros.org >> > https://code.ros.org/mailman/listinfo/ros-users >> > >> >> >> >> -- >> :wq >> >> Google Germany GmbH >> Dienerstr. 12 >> 80331 München >> >> AG Hamburg, HRB 86891 >> Sitz der Gesellschaft: Hamburg >> Geschäftsführer: Graham Law, Katherine Stephens >> >> Tax ID:- 48/725/00206 >> VAT ID:- DE813741370 >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users > > -- :wq Google Germany GmbH Dienerstr. 12 80331 München AG Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Graham Law, Katherine Stephens Tax ID:- 48/725/00206 VAT ID:- DE813741370