DJI L1/L2 Processed workflow with LP360

Requires an LP360 Drone license.

Introduction

This article includes a step-by-step guide on how to process DJI L1 and L2 processed data in LP360. This workflow requires the user to first pre-process the data using DJI Terra desktop and later continue the processing in LP360.

The main difference between the DJI Raw L1/L2 and the DJI Processed L1/L2 workflow, is that the raw workflow only uses LP360, while the processed workflow uses DJI Terra desktop app and LP360.

Pre-Requisites

• Before starting with the workflow, the user will need to have LP360 v2024.2 or newer.
• DJI Terra desktop 4.3 or newer.

DJI L1/L2 Processed Workflow

DJI Terra Pre-processing
Project creation and data import
Import Advanced Settings
Generate flight lines
Post Processing
Strip Align

Other recommended steps:
Smoothing
Control Points
AI Ground Classification

How to process DJI L1/L2 Processed workflow

1. Pre-process the flight in DJI Terra

The first step is to perform the sensor trajectory processing and initial point cloud generation from the raw data is performed in DJI Terra as a pre-processing step before beginning the workflow in LP360 Drone.

2. Project creation and raw data import

1. Select "Import Raw Missions into New Project" on the Startup dialog or select Cycle Import on the Sensor Tab.

2. Under the Sensor Type, select "Processed L1/L2", then press Next 
3. Press "Add DJI Terra Mission Folder"
4. Select the desired cycle folder.

Note: If the DJI Terra folder has been moved to a new location, it is also required to select the raw data location
5. LP360 will select by default the closest CRS read from the DJI Terra files. Usually, these do not always include the vertical datum. Therefore, the user will need to manually select it (in the example, we can see in red the CRS that requires our attention).

6. Define the Projects Root Folder, TrueView Output Project Name and Project Coordinate Reference System and click Finish.

7. Selecting the processed flights to be imported will automatically submit a Reproject (RPJ) Job to the Job Manager for each Cycle/Flight to ensure the LAS and SBET matches the project CRS.

8. Upon completion of the RPJ job by the Job Manager :
a) Job Manager will indicate completion by the green checkmark flashing on the Job Manager icon  
b) The job will need to be completed to view the resulting point cloud.

9. If desired, or for troubleshooting, in Job Manager , select the applicable RPJ job, then select View Log to review the RPJ processing log.
10. In Job Manager , select the applicable RPJ job, then select Open Project to open the applicable project for the job, if not currently open.
11. Then, select Complete Job to add the LAS and TrueView Trajectory file(s) to the project.

3. Flight lines generation

The next step is to generate the flight lines. There are 2 ways to generate flight lines, manual flight lines and automatic flight lines. In this example we will see how to generate automatic flight lines.

1. Select the Auto-Create Flight Lines tool on the DJI tab (or Sensor tab) to open the Auto Create Flight Lines dialog.
2. Select the Min Length

3. Press "Next"
4. In the Edit mode -->Select the desired cycle --> The flight lines of the cycle will appear -->Select the undesired flight lines and press "delete" in the keyboard --> Move to the next cycle --> When finish press "Close"

4. Post-Processing

1. Go to Sensor ribbon –> Post Processing tool.
2. Select the Clip Angle. The maximum Clip Angle is 36deg.
3. Select the Clip Range.

Post-Processing with the recommended settings for the DJI L2 in meters

4. Run Post Processing …
5. Post processing point cloud is generated.

5. Strip Align

The next step will be to verify the alignment of the flight lines and correct it. For that we should perform cross sections in the overlap areas between flight lines. It is recommended to perform this sections in flat areas, buildings are especially useful for it.
We can also use tools like Surface Precision to verify the alignment across the flight or between multiple flights. After we have verify the alignment, we proceed to correct it.
Strip Align tool requires the license addon "Strip Align"

1. Go to Sensor ribbon --> Strip Align
2. Select the LAS to align.
Tip: You can select multiple flights. If you do it, the tool will correct any misalignment between flights. However, if one flight has significant error (or bias), it will introduce error into the new Strip Align layer.

3- Press "Submit Strip Align job"

4- Go to Job manager --> Check the processing status
5- Once Strip Align finish the status will change to "Ready" --> Select the job--> Click "Complete job" Go to "Job manager" --> Check the processing status

Strip Align will create a new LAS, in my case it is called "LAS_SA". This new LAS has all the misalignments corrected. Example: