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GATE 2019 CE (CE2) – Question 43

Geomatics Engineering · Photogrammetry: scale, flying height, parallax, camera calibration · 2 marks · Multiple choice

A 20 cm focal-length camera in an aircraft takes vertical terrain photographs. Average ground elevation is 1200 m MSL. Find required aircraft elevation MSL for photo scale 1:8000.

  1. 2600 m
  2. 2800 m
  3. 3000 m
  4. 3200 m

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Show answer and explanation

Correct answer: (B) 2800 m

Explanation

Vertical-photo scale is $f/(H-h)$. Camera height above terrain is $8000(0.20)=1600$ m. Add ground elevation 1200 m: **H = 2800 m MSL, B**.