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vectr-ucla / direct_lidar_inertial_odometry

[IEEE ICRA'23] A new lightweight LiDAR-inertial odometry algorithm with a novel coarse-to-fine approach in constructing continuous-time trajectories for precise motion correction.
MIT License
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`baselink2imu` and `baselink2lidar` are reversed #49

Open VRichardJP opened 1 month ago

VRichardJP commented 1 month ago

Despites their name, both baselink2imu and baselink2lidar are used as imu->baselink and lidar->baselink transformations in the code.

For example, this line:

https://github.com/vectr-ucla/direct_lidar_inertial_odometry/blob/77b356325dd629cc6f0f1a048bd867ca5ff3d5c3/src/dlio/odom.cc#L1386

converts IMU angular velocity measurement into baselink frame.

Another example:

https://github.com/vectr-ucla/direct_lidar_inertial_odometry/blob/77b356325dd629cc6f0f1a048bd867ca5ff3d5c3/src/dlio/odom.cc#L575-L576

Here, the original LIDAR scan (so in lidar frame) is first transformed by baselink2lidar, as if it was "lidar->baselink".

Not only it makes the code confusing, but it is also easy to miswrite the transforms in the dlio.yaml file. I think it would be better to rename these transforms to lidar2baselink and imu2baselink:

$ grep -rIl baselink2lidar | xargs sed -i 's/baselink2lidar/lidar2baselink/g'
$ grep -rIl baselink2imu | xargs sed -i 's/baselink2imu/imu2baselink/g'

?

kennyjchen commented 4 weeks ago

Good point -- technically yes they represent the transformation from sensor to baselink. Sorry for the confusion.