ROS topics for output

[stephenmcc]

There don't appear to be any ROS output topics for the estimated pose or map, at least for the default settings. It'd be helpful if those could be added in.

[pinkfloydfan]

Hi,

I've partially solved this myself. Kindly refer to my fork of ORB SLAM3 here. I've only done it for the inertial node, however I imagine it'll be similar for the other nodes.

The ImageGrabber class will have a method called to mpSLAM->TrackMonocular which will return a transformation matrix. By default the return variable is not stored, modify ImageGrabber to contain a ros::Publisher and use it to publish pose. It seems older versions of ORB SLAM2 also had the same issue, and I followed the gist of this article to make the appropriate modifications. One thing you have to do is change ORB_SLAM2::Converter::toQuaternion to ORB_SLAM3::Converter::toQuaternion.

Hope this helps.

[stephenmcc]

@pinkfloydfan Appreciate the info, I was able to publish a ROS transform from that TrackMonocular method. However I'm seeing that the axes are: +x when camera moves left, +y when camera moves up, and +z when camera moves backward. This seems odd since this appears to be a left handed coordinate frame, and that +z usually means forward motion.The pangolin window is showing that the SLAM is doing a good job though, so it isn't estimating incorrectly. Any thoughts?

[pinkfloydfan]

@stephenmcc In the pose estimate I'm getting, +z is forwards, -z is backwards, -y is up, +y is down, -x is left, +x is right. Are you using mono-inertial? It might be worth checking the Tbc matrix in the configuration yaml file, which is the transfrom from body coordinates to camera coordinates. Did you use Kalibr or a similar tool?

[stephenmcc]

I just needed to invert the transform that TrackMonocular returned, which I realized after checking your fork. Really appreciate the help!

[sampath-ogmen]

@stephenmcc , would you give us some clue how we can do that , I am using orbslam3 but my robot was moving on upward direction