Pinhole camera model

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In computer vision and 3D computer graphics, the pinhole camera model describes the mathematical relationship between the coordinates of a point in three-dimensional space and its projection onto the image plane of an ideal pinhole camera, where the camera aperture is described as a point and no lenses are used to focus light. The model does not include, for example, geometric distortions or blurring of unfocused objects caused by lenses and finite area apertures. It also does not take into account that most practical cameras have only discrete image coordinates (pixel indices). This means that the pinhole camera model can only be used as a first order approximation of the mapping from a 3D scene to an image plane. Its validity depends on the quality of the camera and, in general, decreases from the center to the edges of the image, as lens distortion effects increase. Some of the effects that the pinhole camera model does not take into account can be compensated, for example by applying suitable coordinate transformations on the image coordinates; other effects are sufficiently small to be neglected if a high quality camera is used. This means that the pinhole camera model often can be used as a reasonable description of how a camera depicts a 3D scene.