Error in update external sensor (LidarView SLAM Not Integrating External Sensor Trajectory Data)

I use a Velodyne VLP-16 LiDAR and an Advanced Navigation (Spatial) GNSS device. I have a *.pcap file with a position orientation reader with global x,y,z, and roll, pitch,yaw. I have generated a csv file with position with timestamp. Now is it possible to slam lidar data with an external sensor, currently I’m facing an issue with doing that.

Hi @Nitin_Garg,

Which version of LidarView are you using?

You should be able to load the csv file in the SLAM filter, in the property dock widget and the field External Sensor File.

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Hope this helps,
Timothée

Thanks for your reply @Timothee_Couble. I am using version 4.5.0 and I have tried the slam filter and selected external sensor file. My csv file is attached below. The trajectory generated by the slam is different from the actual position orientation trajectory. I am giving epoch time in csv.

Please help me to solve this. I am a bit new to this.

Thanks.

RawSensorsnew.csv (1.0 KB)

@Timothee_Couble @Gatien_Ferret

Please help me to resolve this.

Hi @Nitin_Garg,

The external sensor is a measurement in the SLAM, but it is not the only one so the resulting trajectory may not be exactly the same. To make it follow it more closely, set a high value in the Pose Weight field.
Strange thing about your data is that you seem to have only one measurement per second ( each line is incremented by 1 in the time array) when such sensors usually output a much more frequent data.

Also, you need make sure you are providing it a calibration matrix ( to link the pose measurements you have to the LiDAR / SLAM coordinate system ), as explained in the external sensor guide.
For an easier interface, you may use latest LidarView build ( link from there → Download artifacts for your system).

You may subscribe to a contract support ( 10 hours should be sufficient) if you would like us to test directly on your data and debug the process on your data.

I hope this helps.

Hi @Gatien_Ferret,

Thank you for your helpful response.

I have a question regarding which timestamp should be used to synchronize data with GPS/IMU timestamps. The GPS timestamp is in Unix (epoch) format, such as 1718857370.63. However, I’m uncertain which timestamp from the frame (pcap) data should be synchronized with this. The frame data includes timestamp, adjusted time, and frame time.

This question might seem a bit unconventional, but clarifying this will greatly assist me in my work. I have attached updated CSV files below for your reference.

RawSensors_final.csv (3.1 MB)
@Timothee_Couble

@Timothee_Couble @Gatien_Ferret