Determine the process of modelling
The process of modelling is much easier, if mathematical description of an object, or at least of part of an object may be applied. In the first case, however, a mathematical description of the object may be unavailable. One way of solution is to use as a model the coordinates of the infinitely many points of the object, but this is not feasible for a computer with finite storage. More often, the object is merely approximated with pieces (called patches, in the case of surface modelling) of planes, spheres, or other shapes that are easy to describe mathematically, and require that points on the model be close to =corresponding points on the object.