Doubts regarding camera positioning and orientation

[rajmohan747]

Hi, I am using UR5 robot and the ZED camera mounted on a stand kept in inverted position facing downwards. So the Robot frame and the camera frame are having different orientations. According to the camera_position in Tutorial1.launch we can provide only the position (X,Y,Z) of the camera ,which I provided as [0.66,0.18,0.65] (in meters) from Robot base link (0,0,0).

So is it possible to work with camera frame and robot frame in different orientations????

[atenpas]

No, that's not supported. But why not transform the cloud into the robot frame before sending it to GPD?

[rajmohan747]

Thank you @atenpas for your quick reply. Since I am totally new to this domain,could you please provide some help with the transformation.

"/zed/point_cloud/cloud_registered" is the cloud_topic that is passing to tutorial1.launch and the camera is located at a position of [0.66 0.18 0.65 ] with orientation of [3.13 0 3.13] and robot position [0 0 0] with orientation [0 0 0].

As of now I am doing it like,

<node ="$(arg eye_on_hand)" name="dummy_handeye" pkg="tf" type="static_transform_publisher"
            args="0.66 0.18 0.65 3.13 0 3.13 $(arg robot_base_frame) $(arg tracking_base_frame) 10" />

Could you please tell me how to transform cloud into robot frame. before sending it to GPD

[jaymwong]

@rajmohan747; Since your point cloud is registered it's probably under the frame name /zed_rgb_optical_frame or something like that. So, something like,

Eigen::Affine3d world_to_camera_ = tf2::transformToEigen(tf_buffer_.lookupTransform(world_frame_, camera_optical_frame_, ros::Time(0)));
pcl::transformPointCloud(*input_cloud_xyz_, *input_cloud_xyz_, world_to_camera_.matrix());

where world_frame_ and camera_optical_frame_ are your two frames. Then, publish out input_cloud_xyz_ and make GPD subscribe to it.