sdf_map_frame orientation

[sayali-purdue]

GraspPlanner publishes a map on sdf_map_topic. The reference frame of this map is set to sdf_map_frame. This frame is defined in a launch file that invokes grasp planner. E.g. offline_yumi.launch at line 74. I have a few questions about this frame:

1. does the published map (described in this frame) represents the object to be grasped? Or is it a world-fixed frame?
2. how/why did you decide on the orientation of sdf_map_frame to be 'forward-down-left', where Z-axis is not pointing up but to the left?

Would appreciate if someone could describe the sdf_map_frame.

Thank you!

[ksatyaki]

Hi, it has been a long time since I worked on this. I hope that @tstoyanov, @hoangcuongbk80 or @jsll can help you on this. :-)

[tstoyanov]

It's been a long time since anyone has worked on this code base actually. Very glad that you are playing with it, but bear in mind that some parts might have broken down by now. Let me try from memory:

1. This would be a workspace map, or at least the relevant parts of the workspace.
2. No particular constraint here, the axes can be arbitrary of course. If memory serves me right, this particular choice was made because it was the closest orientation to the way the depth camera was pointing ( Z there is the camera axis). It just makes it easier to hand-calibrate and tune.

[sayali-purdue]

Thanks for your response. ROS standard for frames is x=forward y=left and z=up as per REP https://www.ros.org/reps/rep-0103.html. Do you think this axis orientation standard can be used for sdf_map_frame so that it is easier for users to understand the code?

[tstoyanov]

Sure. Make the change in the launch file and open a PR. It really does not matter from my point of view, as long as the parameters are encoded in the launch file, and someone has tested that it really works.

[sayali-purdue]

Thanks. One more question: "Z there is the camera axis": does this mean the current z axis of the sdf_map_frame is in the same direction as z axis of the camera, and this z axis is pointing forward with respect to the camera?