Some scenarios may require you to process your True View data with different lever arm offsets or IMU mounting angles than the ones recorded in the APX-15 at the time of acquisition. For instance, if you move the system to a new drone, but forget to update the lever arm values following the applicable system hardware users guide before collecting data. The steps below explain how to use a lever arm offset override to process your data in EVO with different lever arm offsets. Applies to True View EVO v2021.1.17.0 and later.
Step 1 – Import your cycle into True View EVO.
Step 2 – In Windows File Explorer, navigate to the system folder inside your EVO project folder (Area_ /Cycle_/System_), or a folder of your choosing.
Step 3 – Create a json file named GNSSLeverArmOverride.json that defines one or both of these 3-tuples to define the lever arm offset override:
{
"IMUMountingAngles": {
"Override": "false",
"RefToIMUMountingAnglX": "0.0",
"RefToIMUMountingAnglY": "0.0",
"RefToIMUMountingAnglZ": "0.0"
},
"LeverArm": {
"Override": "false",
"PriGNSSLeverX": "0.0",
"PriGNSSLeverY": "0.0",
"PriGNSSLeverZ": "0.0"
}
}
Or, use these 3-tuples for the True View 620 or 640:
{
"IMUMountingAngles": {
"Override": "false",
"RefToRemoteIMUMountingAnglX": "0.0",
"RefToRemoteIMUMountingAnglY": "0.0",
"RefToRemoteIMUMountingAnglZ": "0.0"
},
"LeverArm": {
"Override": "false",
"PriGNSSLeverX": "0.0",
"PriGNSSLeverY": "0.0",
"PriGNSSLeverZ": "0.0"
}
}
Being sure to set the override to “true” for the desired section(s).
Step 4 – Enter the desired lever arm offsets and/or mounting angles. Save and close the GNSSLeverArmOverride.json file.
Step 5 – In EVO, select the POSPac Processing Wizard and on the Input Settings Page, browse to a JSON file that defines one or both of the 3-tuples above to override the APX values when processing. Configure the remaining as normal.
Step 6 – Confirm the correct offsets were used by examining the GNSS-Inertial Processor Configuration section of POSPac report.
Step 7 – Execute the remaining processing steps as normal. Be sure to re-create the True View Trajectories and subsequent steps if they were previously created with incorrect lever arms used in the POSPac processing.
