Generating the lidar point cloud and orthophoto from the source data requires that the data be correctly positioned using the trajectory of the drone.  This is a post-processed kinematic (PPK) solution accomplished using Applanix’ POSPac processing software to combine the GNSS observations, both base and in-air, with the angular and acceleration data recorded by the on-board inertial measurement unit (IMU) in the APX-15.

How to Create a Post-Processed Trajectory File

Step 1: Cycle

1. Check the Cycle section to validate the correct cycle name and raw position file are being referenced. If you are using the default folder structure, these should not need to be changed.

Processing Range

LP360 Drone will attempt to automatically set the start/end time for the sensor trajectory processing based on the kinematic motion of the sensor. This works in the vast majority of cases, however, there are times where the user may want to change the start time of processing due to a mismatch of when the sensor and base station observation started or GNSS issues with either the sensor or base station during the beginning or ending of the flight. If you are unsure about what time to change, look at your current Post Process Trajectory Report, or generate one with the QC-Only (Realtime) option, and use the charts to determine areas where you may want to exclude due to GNSS data quality issues.

2. Select the Processing Mode you want to use to calculate your positions. See a comparison of the Processing Modes for post processing the sensor trajectory.

Single Base: Single Base Positioning is a GNSS processing mode where a single dedicated base station is employed to provide differential corrections to the rover GNSS receiver. 

SmartBase: Applanix SMARTBase is a web service that uses existing ephemeris data from public base station infrastructure around the world to generate a virtual base station at your trajectory.

PP-RTX: PP-RTX (Post-Processed Real-Time Extended) is a GNSS processing mode that utilizes Trimble® CenterPoint™ RTX technology. It provides centimeter-level post-processed positioning accuracies without requiring local reference stations.

QC only (Realtime): Use this mode for field checks to verify the quality of the rover data. 

3. You need to select which Run Location you intend to use for processing:  

• • • If you intended to run using a local desktop copy of POSPac UAV, select Local. This will require a licensed copy of POSPac UAV installed on the processing machine. Local processing with an owned/purchased TrueView sensor does not use TrueView Points from your pool.

    • If you want to use cloud-based processing, select Cloud and enter/verify your TrueView login information is correct.  All cloud-based processing is subscription-based and will use TrueView Points from your pool.

4. GNSS Settings

5. Review the Cycle Summary section. If using TrueView Points, an estimate for the job plus your current account balance will be shown.

6. Click Next.

Step 2: Base Station

1. Verify the path for the Base Station Observation File(s) is correct.  This is the observation file you downloaded from the base station and copied to the Cycle\System folder on the USB. It was automatically moved to your project folders during the import and project set-up.  If you did not copy the observation file to Cycle\System earlier, you will need to browse to it and select it now using the “+” button.

2. Enter your base station information in the lower section and verify it is correct.  

• • • • Use Computed using Trimble CenterPoint RTX to compute the base station location from the submitted base station file to obtain a coordinate for that survey nail/reference mark. 
      • Use the Survey Nail Manager in the Base Station Location section middle of the dialog to Save your base station definition for future reference.  You can use the dropdown section to recall previously saved Survey Nail locations.

3. Click Next.

Step 3: Review Settings

1. You can review batch processing job estimates. When you are satisfied, click Submit to run your POSPac session.

2. 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.

3. Click Close to dismiss the dialog.

Note - Note that running POSPac UAV does not create any new layers in your project. If you need to externally check the POSPac output was created and added to your project data set, you can browse to the Cycle\POS folder of your project and verify a PostProcessedTraj.txt file was written here. There will also be a new subfolder named POSPac_yymmdd_tttttt for each POSPac job you run. These subfolders contain detailed logs and files related to POSPac processing and are useful for troubleshooting issues.