In satellite photogrammetry to obtain the orientation mostly of satellite scene Rational Polynomial Coefficients (RPCs) are applied. They provide a compact representation of a ground-to-image geometry, that allow for photogrammetric processing without requiring a physical camera model. Model with RPC is provided with satellite image and can be improved using measurements of indirect surveying methods used for control point measurement. The RPC model for the coordinates of the image point is calculated as ratios of the cubic polynomials in the coordinates of the world or object space or ground point.
In photogrammetry and remote sensing, rational polynomial coefficients (RPCs) describe a specific imaging geometry model for transforming image pixel coordinates to map coordinates (thereby accounting for terrain displacement errors). A sensor model describes the geometric relationship between the object space and the image space, or vice versa. It relates 3-D object coordinates to 2-D image coordinates. RPCs are part of a general sensor model that approximates the physical sensor model. The physical sensor model represents the physical imageing process, making use of information on the sensor's position and orientation (during image acquisition). The RPC model often refers to a specific case of the RFM (rational function model) that is in forward form, has third-order polynomials, and is usually solved by the terrain-independent scenario.