Python - Dataloaders

Rosbag Dataloader

The rosbag dataloader works with both ROS1 and ROS2 bags. Place split ROS1 bags together in a single folder and use that folder as the data path. ROS2 bags especially require a metadata.yaml file.

Note

It is not supported to run RKO LIO on partial or incomplete bags, though you may try and are encouraged to raise an issue if you require this supported.

There are certain reasonable defaults:

  • The bag contains one IMU topic and one LiDAR topic (otherwise specify with --imu or --lidar flags).

  • A static TF tree is in the bag. We build a static TF tree from topic frame ids and query it for extrinsic between IMU and LiDAR.

    The odometry estimates the robot pose with respect to a base frame, by default assumed to be the LiDAR frame unless you override this with --base_frame. The TF tree is queried for the necessary transformations.

If there is no TF tree, you must supply extrinsics for IMU-to-base and LiDAR-to-base. Set one transformation to identity if you want that frame to be the reference, but both must be given.

Message header frame IDs must match the TF tree frame names. If they do not, override with --lidar_frame or --imu_frame.

# The config should provide extrinsics if they can't be inferred
rko_lio -v -c config.yaml --imu imu_topic --lidar lidar_topic /path/to/rosbag_folder

Raw Dataloader

When using the raw dataloader, arrange your dataset directory as follows:

dataset_root/
├── transforms.yaml                 # required: contains 4x4 matrices
├── imu.csv / imu.txt               # must match required columns
└── lidar/                          # folder of point clouds
    ├── 1662622237000000000.ply
    ├── 1662622238000000000.ply
    └── ...

  • transforms.yaml: defines two keys (T_imu_to_base, T_lidar_to_base), each a 4×4 matrix. See Extrinsics and conventions.

  • IMU file: Only one file (CSV or TXT) is allowed. Required columns: timestamp, gyro_x, gyro_y, gyro_z, accel_x, accel_y, accel_z. Extra columns are allowed. timestamp in nanoseconds, others in SI units.

  • lidar/: contains scans as PLY files. Each filename is a timestamp (ns) for the scan. Each PLY file must have a time field (accepted names: time, timestamp, timestamps, or t) in seconds.

HeLiPR Dataloader

This loader is deprecated and will be removed in a future release. If you need it supported, please open an issue.