A3 in Practice
In a typical mapping project, A3 cut at least 50 percent of the acquisition time and 50-75 percent of the processing time. The tables below show the figures behind several typical acquisition and mapping scenarios.
| Orthophoto GSD (m) | 0.05 | 0.10 | 0.15 | 0.20 | 0.25 | 0.30 |
|---|---|---|---|---|---|---|
| Max allowed oblique angle (deg from Nadir) | 10 | 17.5 | 22.5 | 25 | 25 | 30 |
| Altitude above ground (ft) | 5,500 | 10,900 | 16,400 | 21,900 | 27,300 | 32,800 |
| Ground Speed (knot) | 180 | 215 | 245 | 275 | 340 | 370 |
| Orthophoto coverage (sq. km/hour) | 176 | 753 | 1,692 | 2,850 | 4,404 | 7,121 |
Acquisition and Processing Case Study
Project scope:
- 1000 km2 coverage
- 14 cm GSD required products
- 180 kts ground speed
- 14000 feet flight altitude
- 2700 meter distance between flight lines
Total image acquisition time: 1.5 Hours including all turns and lifts
| Processing Workflow | Processing Time | User Time |
| Download & Pre-processing | 2 Hours | 5 Minutes |
|---|---|---|
| AT & Bundle Adjustment | 23 Hours | |
| Stereo pairs export | 0.5-1.5 Hours | |
| Orthophoto Creation | 18.5 Hours | |
| Total Processing Time | 45 Hours | 10 Minutes |
*processed by 4 Intel Xeon-based servers
A3 and Large Format Cameras Comparison
The following table compares the productivity of different large format cameras, providing photogrammetric products in different resolution cases (GSD).
| Parameters | A3 | Typical Large Frame Digital Camera | Standard Analog Camera |
| Focal length (mm) | 300 | 100 | 150 |
|---|---|---|---|
| Pixel Size / Scan resolution (micron) | 9 | 7 | 15 |
| Frame size cross track (pix) | ~62,500 | 15,000 | 15,000 |
| Frame size along track (pix) | 7,850 | 10,000 | 15,000 |
| GSD = 5 cm Max allowed oblique angle (from Nadir) = 10° |
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| Aerial Survey Productivity (sq.km/hour) | 158 | 71 | 50 |
| Productivity comparison | 316% | 142% | 100% |
| GSD = 25 cm Max allowed oblique angle (from Nadir) = 25° |
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| Aerial Survey Productivity (sq.km/hour) | 3,363 | 1,524 | 1,067 |
| Productivity comparison | 316% | 143% | 100% |
