ros
Missing convertions
Once understood the convert method is quite helpfull. But IMO there are some basic convertion methods missing.
For example: tf2_geometry_msgs.h missing Vector3, Pose, Point (only stamped versions available) tf2_eigen.h missing Quaterniond, Matrix3d
Furthermore the documentation on creating convertion methods is incomplete or hard to find.
right, this documentation needs advertisement, like on the wiki. You mention a few types, but what would they convert to ? Thx
Nice convertions would be: Eigen::Quaterniond <=> geometry_msgs::Quaternion Eigen::Vector3 <=> geometry_msgs::Vector, geometry_msgs::Point Eigen::Matrix3d <=> geometry_msgs::Matrix Also great (but might be incompatible) Eigen::Matrixxd <=> geometry_msgs covariances (e.g. float64[36])
Ok, if you have any other types that you'd like to have converted, please add in here.
Eigen::Vector3 <=> geometry_msgs::Vector, geometry_msgs::Point
is a tricky one: a vector is not the same things as a point in ROS (a vector is a direction, that is therefore not translated when a transform is applied to it, cf https://github.com/ros/geometry_experimental/blob/jade-devel/tf2_geometry_msgs/include/tf2_geometry_msgs/tf2_geometry_msgs.h#L77 )
Same with the matrix and the covariance matrix: the info is the same, but not the semantic (same with pose and transform).
Anyway, I need to write the wiki page about conversion and utils.h, and add those conversions above that make sense.
I wasn't aware of the doTransform method. That complicates things.
So what do you recommend for those non-bijective mappings? Should everyone implement them application-specific or not use convert at all?
If it's not bijective it shouldn't use the convert method. You should define a method which captures the semantic meaning, potentially application specific, potentially somewhat generic and shareable between similar applications as any function can be done already.
On Mon, Aug 17, 2015 at 6:44 AM, mistoll [email protected] wrote:
I wasn't aware of the doTransform method. That complicates things.
So what do you recommend for those non-bijective mappings? Should everyone implement them application-specific or not use convert at all?
— Reply to this email directly or view it on GitHub https://github.com/ros/geometry_experimental/issues/116#issuecomment-131821305 .
I agree with @tfoote, but we should define which conversions are the bijective ones and which are not. Because geometry_msgs::Pose is being converted into tf2::Transform in tf2_geometry_msgs.h, but it could have easily been geometry_msgs::Transform instead.
And these conversion functions are replicated in the buffer_core.cpp.
So, I guess there are two things.
- When do we use the convert interface defined in convert.h?
- What is the policy for defining "custom" methods?
