Large velocity and Point cloud timestamp not available

[imkaleem]

Hello, I hope you're doing well. Thanks for modifying it to support a 6-axis IMU.

I'm using the following configs for Ouster Lidar (N_SCAN = 32):

# Topics
pointCloudTopic: "/pointcloud"               # Point cloud data
imuTopic: "/imu"                         # IMU data
odomTopic: "odometry/imu"                   # IMU pre-preintegration odometry, same frequency as IMU
gpsTopic: "gps_odom"                   # GPS odometry topic from navsat, see module_navsat.launch file
useGPS: false

I'm getting some errors using your package. I have attached screenshots of the error messages and warnings.
First, it points to the timestamp error:

But I have time stamps, as it can be seen in the following image:

Secondly, there are large velocity warnings:

Hence, it maps the pointcloud data with huge drifts:

Could you please help me resolving these issues in this regards?

Thanks!

[JokerJohn]

Hi, @imkaleem , Thanks for your questions.

The issue is that the LiDAR point cloud type has not been adapted to your dataset. The “Large velocity” message stems from the same cause and is also crashing the IMU pre-integration node.

Please adapt the data format to your setup using the steps below:

1. Play back the bag and run
   rostopic echo /top_front/lidar_points/fields -n1
   to inspect the basic schema (field names, types, and order) of your point cloud.

2. Define your point cloud structure accordingly, paying strict attention to each field’s type and order.

3. Update imageProjection.cpp to add your format, and extend the cacheProject() function with the corresponding point-cloud handling logic. Ensure dst.time is in seconds, with values in the 0–0.1 s range.