Geometric correction is concerned with placing the reflected, emitted, or back-scattered measurements or derivative products in their proper planimetric (map) location so they can be associated with other spatial information. It is usually necessary to preprocess the remotely sensed data and remove the geometric distortions so that individual picture elements (pixels) are in their proper planimetric (x, y) map locations. This allows remote sensing-derived information to be related to other thematic information in geographic information systems (GIS) or spatial decision support systems (SDSS). Geometrically corrected imagery can be used to extract accurate distance, polygon area, and direction (bearing) information. Geometric correction techniques are dedicated to resolving the geometric distortions caused by: (1) variations in sensor position; (2) Earth curvature; (3) rotation of Earth on its axis; (4) relief displacement. There are two types of geometric distortions, namely systematic and random distortions. The former might be caused by Earth's rotation for example and, therefore they are predictable and systematic. The second type of distortions might be caused by terrain or variations in sensor altitude. Geometric correction includes georeferencing and orthorectification techniques.
Describe the importance of geometric correction when using Earth Observation data
Explain the main causes of geometric distortions
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