Aerial Photography and Photo Interpretation Flashcards
What are some practical applications of Aerial Photography
- map making
- urban and rural planning
- environmental impact studies
- civil law cases
- real estate evaluations
- art
When and who took the first aerial photograph?
Gaspard Felix
- 1859
- used a balloon.
Oblique Photography
What does it enable?
What are its downsides?
- side views of features, enables general interpretation
- difficult to take measurements
Vertical Photography
What does it enable?
What is one benefit from using this?
Top down views of features, enable more detailed interpretation (measurements etc.)
- Allows more quantitative interpretation
How do we define colour?
3
Hue - the property of colours, determined by the dominant wavelength of the light.
Chroma - intensity, saturation or purity of a colour/hue. (A measure of lack of black or white)
Value - lightness and brightness, the relative abundance of primary colours
In terms of image properties, what does ISO mean?
What would Slow (low) Iso need in terms of light?
- ISO = amount of light needed
- fast (high ISO) requires less light
Slow (low ISO) requires more light.
Film Characteristics: in terms of speed and resolution, how does crystal size effect this?
- larger crystals create fast films with less resolution
- smaller crystals provide slower film at a higher resolution
What types of photography use filters?
panchromatic and colour photography
What are filters used for?
Designed to absorb certain reflected wavelengths and transmit others.
When would you use a blue filter?
To remove the shorter wavelengths where most atmospheric noise is created.
Why would you us a UV filter?
Use glass UV filter to remove effects of UV radiation and protect the glass lens.
What does an IR filter do?
Removes all visible light, only transmits IR radiation.
Define resolution.
The capability of a film or lens to image spatial details
How is resolution expressed in photography?
How do you find Rs?
- expressed in terms of lines per millimetre
- examine smallest pattern: line pairs/mm
Ground Resolution Determination, how can you find ground resolution?
Rg =(Rs x f) / H
Rg = ground resolution in line pair/meter
Rs - system resolution in line pairs per millimeter
f = camera focal length in millimeter
H= height above ground inmeters
