how to manually translate a point from one frame to another

edit

just to extend to this question.

a dynamic way to find transforms should be to use transform listener (from tf2)

add the following dependencies

#include <tf2_ros/buffer_interface.h>
#include <tf2_ros/transform_listener.h>
#include <tf2_eigen/tf2_eigen.h>

(you should also add in CMakeLists.txt and pckage.xml) then you create a transform listener and buffer (in header should be awesome):

tf2_ros::Buffer tf2_buffer__;
std::shared_ptr<tf2_ros::TransformListener> tf_listener_ptr__;

inside the class definition declare the transform listener using you buffer:

tf_listener_ptr__.reset(new tf2_ros::TransformListener(tf2_buffer__));

then, alwasy you want to have a transform, just do:

geometry_msgs::TransformStamped transform = tf2_buffer__.lookupTransform("odom","base_footprint", ros::Time(0), ros::Duration(0.5));

another way to do it (more static, in case the transform never change) is using eigen library https://eigen.tuxfamily.org/dox/group... This way you can find easily a transform matrix given the values you put in the question

thank you for the tips! I also found another method:

tf2_ros::BufferInterface -> transform (const T &in, T &out, const std::string &target_frame, ros::Duration timeout=ros::Duration(0.0))

I'm in doubt about the meaning of ros::Duration(0.0), means "generate an out pose based on the last available transform"