Aerial Photography Fundamentals
Aerial photography — the oldest form of remote sensing — remains vital for detailed mapping, providing high-resolution imagery from aircraft and drones.
Theory & Foundations
Aerial photos capture visible-light images from above, offering centimeter-level resolution unmatched by most satellite sensors.
Types: Vertical (nadir, looking straight down) vs Oblique (angled, showing building facades and terrain perspective). Vertical is used for mapping; oblique for visualization.
Scale = focal_length / flying_height. Higher altitude = smaller scale = less detail. A 150mm lens at 3000m gives 1:20,000 scale.
Stereo coverage: 60% forward overlap creates stereo pairs for 3D viewing and height measurement using parallax. 30% side overlap ensures complete coverage.
Photo interpretation: Tone, texture, pattern, shape, size, shadow, site, and association are the eight elements used to identify features from aerial photos.
In-Depth Coverage
Photo Interpretation Elements
Eight elements help identify features in aerial photos.
- Tone: Light/dark variations indicating material
- Texture: Coarseness — smooth water vs rough forest
- Pattern: Regular (orchards) vs irregular (natural)
- Shape: Regular = man-made, irregular = natural
- Shadow: Reveals height and shape of features
- Size: Relative dimensions help identification
- Site: Location context (bridge over river)
- Association: Features found together (school+playground)
Stereo Vision
Overlapping photos enable 3D perception.
- 60% forward overlap creates stereo pairs
- Parallax differences reveal height differences
- Stereoscopes: Pocket, mirror, or digital viewing
- Modern: Digital photogrammetry automates 3D extraction
Key Techniques
Data Visualization
- Mapping: 40%
- Survey: 25%
- Inspection: 20%
- Historical: 15%
- 🎨ToneLight/dark material differences
- 🌊TextureSurface roughness patterns
- 🔷ShapeRegular=man-made, Irregular=natural
- 🌓ShadowReveals height and form
Practical Workflow
- Plan flight lines and overlap
- Calculate required scale and altitude
- Execute photo mission
- Develop/process imagery
- Create stereo pairs
- Interpret features using 8 elements
- Digitize features into GIS
- Orthorectify for accurate positioning
Software & Tools
Video Tutorials
Real-World Application
Real-World Projects
National mapping from aerial photography.
Case Study
Problem-Based Learning
City growth study needs historical baseline data.
Solution: Obtain 1960s aerial photos from national archives. Georeference to modern coordinate system. Digitize land use boundaries. Compare with current satellite imagery.