Features

Introduction

At times a LiAir system will need to have its boresight calibration parameters recalculated. These values are specific to each device and stored within each system’s configuration file. Some LiAir models store the calibration values are stored in .cal, .ini, or .db files that the user must load into LiAcquire or LiGeoreference before processing LiAir data. While newer LiAir models have system calibration files are save on their internal storage and are written directly into each LiAcquire project file (.sml file) or LiGeoreference project file (.live), thus there is no need to import them into LiAcquire or LiGeoreference during data processing. This How-To Guide provides instructions that should be followed when a need arises to re-calibrate a LiAir system. Please follow it carefully and send any questions or feedback you may have on its contents to support@greenvalleyintl.com.

Workflow Overview

Step 1: Identify a suitable LiAir calibration flight area
Step 2: Program calibration flight plan
Step 3: Send LiAir calibration flight project data to GVI Technical Support team
Step 4: Download new LiAir calibration file provided by GVI Technical Support team

Detailed Procedure

Step 1: Identify a suitable LiAir calibration flight area GVI technical support technicians will recalculate LiAir boresight calibration parameter values using point cloud data collected from the measurement of specific surface feature types. Namely pitched, planar building roofs and flat, hard surfaces such as paved roads or parking lots. Examples of suitable calibration flight areas must contain features like those shown in Figure 1. Surface feature types that resemble those shown in Figure 2 are not suitable for LiAir calibration flights. LiAir operators should also make sure that the calibration flight area is located outside of places with there sUAS operation is prohibited or poses a threat to safety of life or property.

Figure 1. Required land cover and surface feature types that must be found in LiAir calibration flight area

Figure 2. Surface feature and land cover types that are NOT SUTABLE for LiAir calibration flights

Step 2: Program LiAir Calibration Flight Plan
We currently recommend users program the LiAir calibration flight plan using DJI’s GSPro application. Calibration flight plans must meet specific criteria for them of to be of use to GVI’s Technical Support Team during the calculation of LiAir boresight rotation and translation parameter values. Figures 3-5 illustrate an annotated flight route that meets the necessary spatial requirements of an effective calibration flight. Flight speeds should be held constant at 5 meters per second and the flight height should be kept fixed at 50 m above the take-off and land-site elevation (i.e. no terrain following). Two separate flight should be made following the same flight plan. Two (2) INS calibration figure-8 maneuvers should be manually flow at the same height as the calibration flight route after takeoff and before landing. In total, 4 figure eight maneuvers should be performed during the calibration flight. The total flight time of the flight route described in the figures below is approximately 16 minutes to complete including the 5-miniute INS initialization periods that must take place BEFORE TAKEOFF and AFTER LANDING.

Figure 3

Figure 4

Figure 5

Step 3: Send LiAir calibration flight project data to GVI Technical Support team

After the LiAir calibration flight has been completed download the project data including the project folder stored on the devices internal hard drive, the associated base station data, as well as the camera images (if applicable). Add all of these files to a single folder, zip it up, and share with GVI Technical Support Representative. Be sure to include the LiAir model type and system Serial Number (SN) in your support case description before submitting.

Step 4: Download new LiAir calibration file provided by GVI Technical Support team
Once a GreenValley International Techincal Support Team member has finished calculating the LiAir boresight correction parameter values based on the submitted calibration flight data they will send back a new system configuration file.