How does georeferencing work in digital aerial photography?
Digital aerial photographs, either taken from a digital camera or scanned from a printed photo, are raster images. A raster image has a grid-based file where every grid cell or pixel (picture element) has a numerical value. Some raster files have georeferencing information embedded in a header record; others have a secondary metadata file.
What is the science of using aerial photography?
Airphoto interpretation is the science and art of identifying, measuring and analyzing geographic features on the Earth’s surface from aerial photographs and relating these features to other items and activities occurring on the Earth. Photogrammetry is the science of making measurements from aerial photographs.
How is the scale of an aerial photograph calculated?
Photogrammetry is the science of making measurements from aerial photographs. In its simplest form photogrammetry can be used to calculate the scale of a vertical aerial photograph by measuring the straight distance between two points on the photograph and comparing the same distance on a map that already has a known scale.
What’s the difference between low oblique and high oblique aerial photography?
A low-oblique aerial photograph is taken at an angle that does not show the horizon; a high-oblique aerial photograph includes the horizon (Figure 1). A low-oblique photograph is normally used for identification purposes and a high-oblique aerial photograph is more suited for pictorial and illustrative purposes.
How is the ground coverage of a photograph determined?
Ground coverage of an image is the area on the ground (the square ABCD of Figure 4.3) covered by the four corners of the photograph a’b’c’d’ of Figure 4.3. Ground coverage of a photograph is determined by the camera internal geometry (focal length and the size of the CCD array) and the flying altitude above ground elevation.
What are the index numbers for aerial photography?
Each photograph of the stereo pair provides a slightly different view of the same area, which the brain combines and interprets as a 3-D view. Roll and Photo Numbers: each aerial photo is assigned a unique index number according to the photo’s roll and frame.