visualize BLAM with a running Ouster LiDAR sensor

[k-mohit]

Hi,
I have installed BLAM and now I am trying to get a live visualization with the help of BLAM, but I do not know how to do it. I used the command roslaunch blam_example test_online.launch and then rviz but I see nothing. Any help will be appreciated

[oldjimmypku]

hello there,
I'm facing the same problem. It's seems like there is no fixed frame for TF. we need to add a tf to rviz,
But I don't know how yet.

[k-mohit]

@oldjimmypku I think it is possible with static_transform_broadcaster tho not sure how exactly

[DangMinh24]

Hi @mohit-khosti , can you check which frame does Ouster LiDAR is using? I have not had experience with Ouster, but I use Velodyne 16 (it uses /velodyne frame).

[k-mohit]

Hey @DangMinh24 i believe it is /os1_cloud_node/points

[DangMinh24]

/os1_cloud_node/points is a topic, not a tf frame. To know which frame LiDAR are using, run the viz.rviz file and look at Global Options -> Fixed Frame

[k-mohit]

Hi @DangMinh24 thanks for the info, I followed the steps you mentioned and the frames are os1_sensor os1_imu os1_lidar what do I do next?
thanks!

[DangMinh24]

Hi @mohit-khosti, if you use along with the robot (then there will be a frame called odom or odometry, then probably you want to make sure there is transition between this frame and the frame that Ouster LIDAR are using (static_transform_broadcaster is the right tool). However, if you use alone with LIDAR only, probably you want to change parameters in test_online.launch file.

Try change /velodyne_points to /os1_cloud_node/points

[k-mohit]

Hi @DangMinh24 I am only working with the LiDAR sensor and no robot. I did change the parameters in test_online.launch file, however I see an error in the rviz window "Fixed Frame No tf data. Actual error: Fixed Frame [map] does not exist.
Besides, I am not sure how to implement the static_transform_broadcaster solution.
Thank you!

[DangMinh24]

@mohit-khosti Can you change fixed parameter back to world in base_frames.yaml file? If you use sensor alone, the original parameter should work fine.

[k-mohit]

@DangMinh24 I tried looking up the base_frames.yaml file in the blam folder, however I cannot find it. Is it possible that you meant blam_frames.yaml?