# Creating Custom SLAM Trajectory

**URL:** https://discourse.paraview.org/t/creating-custom-slam-trajectory/14292
**Category:** LidarView, Lidar, and SLAM
**Created:** [March 29, 2024, 2:30am UTC](https://discourse.paraview.org/t/creating-custom-slam-trajectory/14292 "2024-03-29T02:30:06Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![Gatien\_Ferret](https://discourse.paraview.org/user_avatar/discourse.paraview.org/gatien_ferret/32/9789_2.png) [@Gatien\_Ferret](https://discourse.paraview.org/u/Gatien_Ferret)
#### Post date: [April 2, 2024, 8:23am UTC](https://discourse.paraview.org/t/creating-custom-slam-trajectory/14292/4 "2024-04-02T08:23:52Z")

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Hi @baldpixels,

In order to be able to load an external trajectory, it needs to satisfy the 3 following requirements :

- It shall have the correct formatting: yours seems correct
- It shall come with an external calibration file so that the SLAM know the transform between the poses and the LiDAR data =\> have you provided this file in your test ? And do you know this calibration ?
- It shall be synchronized with the LiDAR time : in your csv file the time array starts at 3 seconds. And hard to say for sure your without your pcap data, but LiDAR data is usually in POSIX time (now would be 1712045779 )

When those conditions are satisfied, you may do the following to use it in the SLAM :.

- Create a SLAM filter.
- Use the “External sensors” field and load a CSV file containing synchronized poses. Change the following parameters: “Undistortion: External”, “Motion extrapolation: External”, “pose weight = 100000000” (this last parameter should appear in a new section at the bottom of the “Properties” window when the CSV file is entered).
- Launch the SLAM.

For refinement at the end: check “Use pose graph”. Check “external pose” in the pose graph settings section and click on “Optimize graph”.

Would it be possible to send your pcap file ( even privately), so we can also have a look and see if the SLAM can also be improved in that scenario without external poses ?

You may also consider using latest LidarView/SLAM.

Artifacts of master are available [here](https://gitlab.kitware.com/LidarView/lidarview-superbuild/-/jobs/9560755/artifacts/file/build/LidarView-master-4.5.0-107-g04576769.zip)

Latest release available [here](https://gitlab.kitware.com/LidarView/lidarview/-/releases/v4.5.0)

Hope this helps,

Gatien

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