[ros-users] Map Topic Idea

Damon Kohler damonkohler at google.com
Mon Mar 25 14:54:09 UTC 2013


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 <dereck at gmail.com> 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 <damonkohler at google.com>
> 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!! <davidvlu at gmail.com> 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 <dereck at gmail.com>
>> > 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
>> >>
>> >> _______________________________________________
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>> >> https://code.ros.org/mailman/listinfo/ros-users
>> >>
>> >
>> >
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>>
>>
>>
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