How the Formula Works

This tool plans drone mapping missions by calculating ground coverage, images needed, and estimated flight time.

Ground Coverage per Image

Ground Width (m) = (Sensor Width (mm) × Altitude (m)) / Focal Length (mm)
Ground Height (m) = (Sensor Height (mm) × Altitude (m)) / Focal Length (mm)

Effective Coverage with Overlap

Effective Width = Ground Width × (1 - Overlap% / 100)
Effective Height = Ground Height × (1 - Overlap% / 100)

Images Needed

Images Needed = Area (m²) / (Effective Width × Effective Height)

Example

  • Sensor: 13.2 × 8.8 mm
  • Focal Length: 8.8 mm
  • Altitude: 120m
  • Overlap: 70%
  • Area: 50,000 m²
Ground Width = (13.2 × 120) / 8.8 = 180 m
Ground Height = (8.8 × 120) / 8.8 = 120 m
Effective = 180 × 0.3 × 120 × 0.3 = 54 × 36 m
Images = 50,000 / (54 × 36) ≈ 26 images

FAQs

1. What overlap percentage should I use?
For reliable photogrammetry, use 70-80% forward overlap and 60-70% side overlap. Higher overlap means more images but better 3D reconstruction.

2. Why does overlap matter?
Overlap ensures the photogrammetry software can find matching points between images to create accurate 3D models and orthophotos.

3. How does altitude affect my map?
Higher altitude covers more area per image but reduces resolution (larger GSD). Lower altitude gives better detail but requires more images and flight time.

4. How long will my mapping flight take?
The calculator estimates based on image count assuming ~2 seconds between shots. Add time for battery swaps, setup, and turns between flight lines.

5. What camera settings should I use for mapping?
Use the lowest shutter speed that avoids blur, fixed aperture, and high enough ISO for good exposure. Keep the lens focused at infinity.

6. Can I use this for 3D modeling?
Yes. For 3D models, use higher overlap (80-85%) and fly multiple passes at different angles (e.g., nadir + oblique).

7. What is GSD and why does it matter?
GSD (Ground Sampling Distance) tells you how much ground area each pixel represents. Lower GSD = higher resolution map. It’s calculated the same way as the separate GSD calculator.

Reference Links