Aerial photogrammetry creates 2D or 3D models from aerial photos, often used for topographic maps and in architecture, land development, and environmental studies. Multiple angles are needed for triangulation, and other data may be combined for a full landscape picture.
Aerial photogrammetry is a technique for creating two-dimensional (2D) or three-dimensional (3D) models from aerial photographs, which are pictures of the Earth from a high point, usually an airplane. These photographs are then transformed into models by cartographers. Aerial photogrammetry usually requires photographs of two or more angles of the same area to map the image and may or may not involve computer software.
For the most part, aerial photogrammetry is used to create topographic maps. These maps can be computer models of the terrain in 2D or, more recently, in 3D. The resulting maps and models can be useful in analyzing both small and large geographic areas. These maps can be used as a basis or in combination with Geographic Information System (GIS) data.
Aerial photogrammetry can also be useful in a variety of industries. It is commonly used in architecture and land development. Additionally, these mapping techniques can be used in environmental land studies, such as watershed or deforestation research, urban planning, or even film production.
Most of the images used in aerial photogrammetry are obtained by cameras mounted on the underside of airplanes. If the image is to be taken from a low flight path, the camera is usually mounted on a small remote controlled aircraft. Flight restrictions in many areas prohibit manned aircraft from flying too low over residential and commercial areas.
The flight pattern of the aircraft typically meanders back and forth over an area as the camera records images. This model is intended to allow each area to be photographed from multiple angles. The aerial photogrammetry process almost always requires photographic data from multiple angles.
Photogrammetrists need multiple angles to determine the relative positions of objects in photographs. This process is accomplished by isolating the same points in each photograph and triangulating their positions relative to each other. This process is usually done with the help of a stereo-plotter, specialized computer software, or both. Stereo-plotters allow a cartographer to view two photographs simultaneously to better compare points of interest.
In many cases photographic data may not be sufficient to determine the full picture of the landscape. This can be especially true when creating a 3D landscape model. Therefore, aerial photogrammetry often combines other types of data with photographs using tools such as LiDAR (Light Detection and Ranging), laser scanners or white light digitizers.
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