---
title: "Short note: Planning and taking aerial photographs"
subject: "Surveying II"
chapter: 7
key: "semester_4/surveying_ii:aerial-photography-planning-taking"
source: https://www.bctengineer.com/q/semester_4/surveying_ii/aerial-photography-planning-taking
site: BCT Engineering
---

# Short note: Planning and taking aerial photographs

Surveying II · Chapter 7: Photogrammetry and Remote Sensing

- Asked in: 2078 Chaitra, 4 marks; 2074 Bhadra, 4 marks; 2073 Magh, 4 marks; 2072 Asoj, 4 marks; 2072 Magh, 4 marks (asked 5 times)
- Video: [Flight Planning in Aerial Photogrammetry.](https://www.youtube.com/watch?v=idn3THD8ESo) — Salim K Tutorials
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/surveying_ii/aerial-photography-planning-taking
- Whole chapter: https://www.bctengineer.com/md/semester_4/surveying_ii/chapter-7

## Question

Write a short note on planning and taking of aerial photographs.

## Short answer

Planning determines photo scale S = f/H, flying height, 60% forward and 25–30% side overlaps, flight line orientation, ground control, and suitable season/weather. During photography, the aircraft flies straight, level, and at constant speed, with an intervalometer timing exposures, while camera tilt is kept under 3° and drift corrected.

## Answer

Aerial photography is taken by an aerial camera fixed in an aircraft. Good planning decides cost, accuracy and coverage.

#### Planning (flight planning)
1. **Purpose and scale:** the scale of the photographs (and so the map) depends on the use. Photo scale $S = f/H$, which fixes the flying height $H = f/S$ for the camera focal length $f$.
2. **Area and boundaries:** the project area is marked on an index map and flight lines are drawn parallel to the longer side to reduce the number of turns.
3. **Overlap:** forward (end) overlap of about 60 % for stereoscopic vision and side overlap of about 25–30 % between adjacent strips.
4. **Photo coverage and number:** ground coverage of one photo $= $ photo size $\times$ scale denominator; the air base $B = (1-\text{end lap})\times$ ground coverage; the number of photos is computed from the strip length and strip count.
5. **Ground control:** control points are planned and marked (signalised) before the flight.
6. **Season and time:** clear sky, little cloud and haze, the sun about 30–40° above the horizon to avoid long shadows, and a season with minimum foliage if the ground is to be seen.

#### Taking the photographs
- The aircraft flies along straight parallel lines at constant height and speed with the camera axis vertical (tilt less than 3°).
- The camera is operated by an intervalometer so that exposures give the required overlap.
- Crab and drift are corrected by rotating the camera; the exposure, film speed and filters are adjusted for the light.
- The strips are flown, the film is processed, and the photos are indexed and checked for gaps, tilt and quality.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How is flying height decided in planning?
   A. H = f x S
   B. H = f/S, from photo scale S and focal length f
   C. H = S/f
   D. H = overlap x f
   Answer: B. Photo scale S = f/H, so H = f/S. (Key point: Flying height)

2. What overlaps are normally planned?
   A. Forward 25-30% and side 60%
   B. Forward 10% and side 10%
   C. Forward 90% and side 60%
   D. Forward 60% and side 25-30%
   Answer: D. About 60% end lap gives stereoscopic vision; 25-30% side lap prevents gaps between strips. (Key point: Overlaps)

3. Why are flight lines drawn parallel to the longer side of the area?
   A. To increase tilt
   B. To reduce the number of turns
   C. To increase shadows
   D. To reduce overlap
   Answer: B. Fewer, longer strips mean fewer turns, saving time and cost. (Key point: Flight line direction)

4. Which conditions suit photography?
   A. Heavy cloud and low sun
   B. Midnight
   C. Sun directly overhead with clouds
   D. Clear sky, little haze, sun about 30-40 deg above horizon
   Answer: D. Clear sky and a moderate sun angle avoid cloud, haze and long shadows. (Key point: Best conditions)