Interpretation of Aerial Photographs
One of the most effective tools that the geographer can use for the interpretation
of the landscape is the aerial photograph.
The benefits of using aerial photographs are many:
Whereas maps have symbols with an established meaning, aerial photos have
different tones and patterns which must be distinguished and given a meaning
by the interpreter.
- When a scene is being viewed through an aerial photo, there is an immediate
feeling of "naturalness", for the images can be intuitively understood
by the observer
- The topographic map is the result of a selective process with symbols
representing selected real world features. Many facets of the landscape
have to be omitted. This selectively is achieved at the expense of complex
reality which is the forte of aerial photography
- Aerial Photographs do not suffer from problems of human error in the
way that maps sometimes do.
- SIZE- In using this property of an object, the photo
use an object or shape he/she recognizes and from this absolute size other
objects can be placed into their relative size brackets.
- SHAPE - Of all the properties in this list, shape is frequently
factor that provides the key evidence for the interpreter. This is especially
the case with respect to landform interpretation where the external form
of a feature is its identifying mark.
- TONE - This property of a photograph is a result of the
reflectivity of the surfaces that compose the earth's crust. No feature
has a constant tone, for this will vary with the reflectivity of the object,
the weather, the angle of light on an object and moisture content of the
surface. The sensitivity of the response of tone to all the aforementioned
variables makes it a very discriminating factor. Slight changes in the
natural landscape are more easily comprehended because of tonal variations.
- PATTERN - The spatial distribution of man-made or natural
frequently a vital clue to their identity.
- TEXTURE - This is a difficult property to describe, but it is
a way of characterizing the smoothness or coarseness of the image on the
photo. Texture involves the total sum of tone, shape pattern and size,
which together give the interpreter an intuitive feeling for the landscape
being analyzed. This property is not one that can be pegged down accurately,
in definitional terms, but is nevertheless vital to the understanding of