In some fields (graphics?) some folks like to make a strong distinction between a point and a vector, but I agree that it is redundant to have both. I would also definitely vote for combining Transform and Pose, since the message type conversions are cumbersome. It raises the question of which name to keep... I would vote Transform, since it is more general. --Adam Adam Leeper Stanford University aleeper@stanford.edu 719.358.3804 On Tue, Oct 19, 2010 at 7:11 AM, Armin Hornung < HornungA@informatik.uni-freiburg.de> wrote: > Alright, I changed the message title so that maybe there can be more > opinions on it. If you haven't read it, see full message below for > reference (which was a reply to Tully's notification of common_msgs API > changes) > > Am 15.10.2010 13:57, schrieb Andreas Tropschug: > > As I see it (which is based on, well... only me) > > > > This inconvenience is related to geometry_msgs being > > "message" types. Messages are often autogenerated types. > > They are not meant to do math with, they are a serialization wrapper. > > > > I am guessing one should convert to tf (bullet) types with the > > tf::MsgToTf() family of functions as soon as they are not > > messages anymore, but mathematical entities. > > Then all the consistencies (Poses being only typedefs of transforms for > > instance) and > > math operator goodies are all there. > > That's all correct, but that still doesn't explain why there should be > both Pose[Stamped] vs. Transform[Stamped], and Point vs. Vector3 > messages. In fact, it only creates more confusion because now there also > need to be more conversion methods to and from tf or bullet to do math. > And for some navigation-related things (see the example I mentioned > about Odometry), you even need to fill in *both* types of messages. > > If there's only a historical reason that there are both, then I feel > like they should be merged for Diamondback (i.e. 22nd of October? What > else needs to be done until then for that?) > > > Best regards, > Armin > > > > > Am 15.10.2010 11:02, schrieb Armin Hornung: > >> Am 08.10.2010 19:51, schrieb Tully Foote: > >>> If you want changes in common_msgs for diamondback please pay > attention. > >> I'm not sure if that's worth a review or change, or if I'm just unaware > >> of some details. But I always wondered why there is a difference between > >> geometry_msgs::Pose[Stamped] and Transform[Stamped]. The data fields are > >> identical, the only difference I see is semantically (translation as > >> "Vector3" vs position as "Point", rotation vs orientation). This makes a > >> quick (& efficient) conversion between the two not possible, the > single > >> fields have to be copied instead (which I see myself doing quite often > >> e.g. in a localization code; best example: [1]). > >> > >> This boils down to Point vs. Translation, is there a reason to have > >> both? Mathematically this is really the same (a point is just a > >> translation from the origin), with only a very small semantic difference > >> (which could be expressed in the variable or topic name at hand, if > needed). > >> > >> [1] > >> > http://www.ros.org/wiki/navigation/Tutorials/RobotSetup/Odom#Writing_the_Code > >> > >> Best regards, > >> Armin > > > > _______________________________________________ > > ros-users mailing list > > ros-users@code.ros.org > > https://code.ros.org/mailman/listinfo/ros-users > > > -- > Armin Hornung Albert-Ludwigs-Universität > www.informatik.uni-freiburg.de/~hornunga Dept. of Computer Science > HornungA@informatik.uni-freiburg.de Humanoid Robots Lab > Tel.: +49 (0)761-203-8010 Georges-Köhler-Allee 79 > Fax : +49 (0)761-203-8007 D-79110 Freiburg, Germany > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users >