Missing convertions about geometry2

[vrabaud]

right, this documentation needs advertisement, like on the wiki.
You mention a few types, but what would they convert to ? Thx

[mistoll]

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])

[vrabaud]

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.

[mistoll]

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?

[tfoote]

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?

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[cmansley]

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?

[tfoote]

#202 adds the primatives for geometry_msgs