A3 in Practice

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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.

A3 Orthophoto Acquisition Efficiency Table
Orthophoto GSD (m) 0.05 0.10 0.15 0.20 0.25 0.30
Max allowed oblique angle (deg from Nadir) 10 15 17.5 22.5 25 25
Altitude above ground (ft) 5,500 10,900 16,400 21,900 27,300 32,800
Ground Speed (knot) 160 230 240 240 260 300
Orthophoto coverage (sq. km/hour) 158 683 1,261 2,212 3,363 4,662

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°
Aerial Survey Productivity (sq.km/hour) 158 71 50
Productivity comparison 316% 142% 100%
GSD = 25 cm
Max allowed oblique angle (from Nadir) = 25°
Aerial Survey Productivity (sq.km/hour) 3,363 1,524 1,067
Productivity comparison 316% 143% 100%