Mobile Mapping Processing Guide

Introduction

This article is meant to guide new Mobile Mapping users on how to process collected data with LP360. This workflow is recommended for any Mobile Mapping user. We've included a step-by-step guide to assist you with your processing.

Pre-Processing

For this data, LP360 Drone is used to reproject the data to various coordinate reference systems and clean up the LiDAR data, plus utilize the extensive capabilities of LP360 Drone for classification, vectorization, and derivative product generation. 

Import

1. Select "Import Raw Missions into New Project" on the Startup dialog or select Cycle Import on the Sensor Tab.
   • If data has been collected using the Ladybug camera refer to Importing Ladybug Camera
2. Under the Sensor Type, select "TrueView / Microdrones", then press Next
3. Select the the cycle folder containing flight/mapping information

Figure 1: Raw Mission Import Wizard - Input Flights

4. Press Next
5. Add the Base Station Observation Files that correspond to the mission.
   • This step is optional for import. Base observation files can be added in trajectory processing.

Figure 2: Raw Mission Import Wizard - Base Observation Files

6. Once satisfied, press Next.
7. Select the Project Output Folder.
8. Select the Project Coordinate Reference System (CRS). This is the desired project CRS.

Figure 3: Raw Mission Import Wizard - Output True View Project

9. Press Finish

Figure 4: Imported Mobile Mapping Project Example

Point cloud generation

Flight lines generation

1. Select Auto Create Flight lines on the Sensor Tab
   • Adjust parameters (Min Length, Turn Radius, and Max Deviation) if desired
2. Press Compute Flight Lines (figure 4)

Tips for Flight Lines Parameters:

• Use the Measure tool  on the Map Toolbar to learn approximately the flight line length.
• Make the Min. Length smaller than the smallest desired flight line.
• Increase Max. Deviation if terrain following is used. The example is in feet.

Figure 5:  Flight Lines - Compute Mode

3. Once satisfied, press Next to enter Edit Mode (figure 5)
4. Select the undesired flight lines and delete them using the Delete key on your keyboard. Press the Enter key to confirm the deletion.
   • It is possible to create flight lines manually on the Sensor Tab.

Figure 6: Auto Create Flight Lines - Edit Mode

Trajectory Processing

1. On the Sensor Tab, select the Trajectory Processing tool.
2. Check the Cycle section to validate the correct cycle name and raw position .T04 file are being referenced.
   • If you are using the default folder structure, these should not need to be changed.
3. Verify the path for the Base Station Observation File(s) is correct.
   • If the base observation files were not added during import, they can be added on the second page of the Trajectory Processing dialog.
4. You can review batch processing job estimates. When you are satisfied, click Submit to run your POSPac session. 
   • The job progress may be monitored using the Job Manager .
5. Upon completion, the Job Manager will indicate completion by the green checkmark flashing on the Job Manager icon
6. Select the job in the Job Manager and press Complete Job on the right-hand side of the dialog. 
   • The session will complete and ask you if you want to review the POSPac Report.  This can be useful as a rapid check on the results. The Position Errors RMS section of the report can provide an accuracy assessment.  The final Export Summary page can verify the output reference frame was set correctly for your project.
7. Click Close to dismiss the dialog.

Geocoding

1. On the Sensor Tab, select the Geocoding tool
2. Disregard the Clip Angle.
3. Select the Clip Range
   • Tip: If you want to generate all the points with no filter, uncheck "Clip Angle" and "Clip Range".

Figure 7: Geocoding - No Clip Angle

4. Press Calibration File
5. Choose Browse for Calibration File to select the SystemConfiguration file that corresponds to the Angle used during collection. 
   • If using the Ladybug Camera, be sure to select the respective JSON file. 

Figure 9: Mobile Mapping Points

Camera Calibration with Ladybug

If collecting data with the Ladybug refer to Ladybug Calibration on how to check a specific camera. Adjusting the accuracy of the data using targets visible to the Ladybug. Accuracy can be monitored through the camera calibration report once the process has been completed. 

Next Steps

Control Points

If interested in 3D accuracy assessments using Accuracy Stars, Checkerboards, and/or Concentric Circles , users must have the 3D Accuracy Add-On License Product.

If you are only interested in estimating the accuracy of Z (elevations), check the Delta-Z Only option in the top left-hand corner of the Control Points Report Dialog and no additional licensing is required.

The intention of this step is to add check points and compare them to our point cloud to estimate the accuracy and review for any bias (constant offset in all the point cloud). If there is, we can remove it it and create a final QC accuracy report.

Smoothing

This step is optional. The Smoothing PCT will help reduce the point cloud noise envelope or the thickness of the point cloud. This algorithm works well for manmade structures, flat areas or regular surfaces. For information on how this tool works, please visit the Data Smoothing in LP360 page.

Exporting or Extracting Final Products/Deliverables

Using the Export Wizard, a variety of deliverables can be exported from LP360.

• For users interested in extracting (or clipping) a section of a raster or LAS layer, see the links below:
  • How to Create an AOI Feature Layer
  • Export using Cookie-cutting by Polygon