| 89 | | The second stage in the calibration process is to calibrate the range offsets. |
| | 89 | The second stage in the calibration process is to calibrate the range offsets. |
| | 90 | |
| | 91 | Can do range correction if the boresight results are good. This is a 2 stage process: |
| | 92 | |
| | 93 | * 1. Nominal offset determination A1 |
| | 94 | * 2. Define relative differences for A2,A3,A4 and B1,B2,B3,B4 |
| | 95 | |
| | 96 | points have approx. the same range error within +/-7 degrees of Nadir, so we look only at this region firstly. |
| | 97 | |
| | 98 | == Procedure == |
| | 99 | |
| | 100 | 1. Start up ALS Post Processor |
| | 101 | * In filters dialog set the angles to +7 and -7 degrees |
| | 102 | * Change the output directory (to 02a_Roff+-7deg if using suggested directory structure) |
| | 103 | * Run the processing on the 4 low altitude flight lines. |
| | 104 | |
| | 105 | 2.Load the results into Terrascan and use the 30-40 GCPs of the calibration site. |
| | 106 | * Tools -> Output Control Report |
| | 107 | * Browse -> GCP file and remove bad points (maybe an error occurred in the surveying of a certain point) |
| | 108 | * Look at the dz value, the average dz is used for the nominal range offset A1. |
| | 109 | * Save the text file. |
| | 110 | |
| | 111 | 3. Preferably using data including areas of forest and the BIT mode data, run Rangecardcal (from ALSPP tools menu) |
| | 112 | * Enter the average dz value as A1 to get the other offsets. |
| | 113 | * Add the outputs to the ALSPP dialog and save the settings reg file (to a new name) |
| | 114 | |
| | 115 | 4. Analyse the results |
| | 116 | * Check these results and re-run using the full FOV (~45 degrees) |
| | 117 | * Check average dz is less than 1cm or so, and standard deviation <5cm in Terrascan control report. (also look at cross sections) |
| | 118 | * Then process the 4 high altitude flights in ALSPP and check in TerraScan (around nadir and swath edges) |
| | 119 | * Finally load in all flights into Terrascan (within a fence if memory issues) and check them (ideally along a stream because this has a “good” profile) Can use the travel path tool in Terrascan for comparing cross sections along a path. |
| | 120 | |