In photogrammetry, the original image of aerial photography is () projection?

Orthographic image is a remote sensing image with orthographic projection properties. Due to the influence of the internal state change, external state and surface condition of the sensor during imaging, the original remote sensing image has different degrees of distortion and distortion. The geometric processing of remote sensing images not only needs to extract spatial information, but also needs to resample the image gray level according to the correct geometric relationship to form a new orthophoto image.