Stereographic (conform)：. Maintains angles.[翻译请求] This mapping would be ideal for photographers because it doesn't compress marginal objects as much. Samyang is the only manufacturer to produce this kind of fisheye lens, but it is available under different brand names. This mapping is easily implemented by software.
Equidistant (linear scaled)：. Maintains angular distances. Practical for angle measurement (e.g., star maps). PanoTools uses this type of mapping.
Equisolid angle (equal area)：. Maintains surface relations. Every pixel subtends an equal solid angle, or an equal area on the unit sphere. Looks like a mirror image on a ball, best special effect (unsophisticated distances), suitable for area comparison (clouds grade determination). This type is popular but it compresses marginal objects. The prices of these lenses are high, but not extreme.
Orthographic：. Maintains planar illuminance. Looks like an orb with the surroundings lying on < max. 180° aperture angle.
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