On Fri, 2010-05-21 at 22:03 -0500, Jack O'Quin wrote: 
> On Fri, May 21, 2010 at 9:35 PM, Tully Foote <tfoote@willowgarage.com> wrote:
> 
> > With regards to a location of a potential GPS message within the ROS package
> > ecosystem, as the maintainer of common_msgs this seems like a strong
> > candidate for inclusion in the sensor_msgs package.
> 
> Good idea. I hadn't thought of that. I was imagining a new package
> defining both the messages and some utility functions.
> 
> Putting just the messages in sensor_msgs is better. There might end up
> being two or three messages, depending on how people decide to
> structure it.

sensor_msgs seems like a good place for the messages. I think it should
be three messages; GPS fix, status and waypoints/landmarks. A message
that describes a moving object may also be useful for swarming aircraft.

> > As for the library components doing a package proposal for gps_common would
> > be a good idea.
> 
> I just realized that Ken Tossell already has a gps_common package in
> the umd-ros-pkg (University of Maryland). Looks like it only has a
> message definition right now.
> 
> Whether we call it that or something similar, should it be a separate
> stack or part of some existing one?

I would guess that the gps related functions belong in a package in the
navigation stack. I think gps_common sounds like a reasonable name.

Great circle distance between the current gps position and waypoints
would be a useful function. Functions to calculate the heading to the
next waypoint and time to next way point at current speed may also be
useful.

I imagine a waypoint/landmark being a position with a rectangular of
spherical volume, an optional desired heading, and a text label.

I am willing to try to find some time this weekend to put together the
review page with a summary of the current ideas for the package and
messages if/when we have consensus on where they belong.