Brief introduction of orthophoto image

Orthographic image is a remote sensing image with orthographic projection properties. Due to the influence of the internal state changes of the sensor (optical system distortion, scanning system nonlinearity, etc.), the original remote sensing image has different degrees of distortion and distortion. ), external state (such as attitude change) and surface condition (such as curvature of the earth and topographic relief). Geometric processing of remote sensing images not only extracts spatial information, such as drawing contour lines; It is also possible to resample the image gray level according to the correct geometric relationship to form a new orthographic image. Orthophoto production is mainly carried out by special equipment, such as aerial photos projected from the center of the flat ground, and an optical mechanical corrector can be used.