On Mon, Mar 25, 2013 at 11:10 AM, Dave Hershberger
<hersh@willowgarage.com> wrote:
> I wish I had time to actually work on this right now.  Failing that I will
> just suggest:
>
> Please don't break backwards compatibility.  It makes unnecessary work for
> lots of people down the road, and doesn't save that much work now.  It's
> hard enough migrating from one ROS release to the next already, let's not
> (knowingly) make it worse.

+1

> My suggestion is to make a new message, called CompressedOccupancyGrid.  It
> would look exactly like OccupancyGrid, but would have an "encoding" byte
> which would support PNG and maybe some other lossless encoding method that
> is more optimized for speed rather than compression size.  (A simple
> run-length encoding might do pretty well.)
>
> Next step might be to make a library for subscribing/publishing
> OccupancyGrid and/or CompressedOccupancyGrid so that code doesn't need to be
> repeated and so nodes can have a consistent message API going forward.
> Maybe map publishers advertise "map" and "map/compressed" and only publish
> to whichever topic gets subscribed to.  Subscribers would look for
> "map/compressed" and "map" and subscribe to compressed if available and
> uncompressed if not.  This way new code would work with old code but be fast
> if possible.

Good ideas.

Maybe we can use something like image_transport as a model.
--
 joq