An Introduction to Splines for Use in Computer Graphics and Geometric Modeling

The most basic output primitives in every computer graphics library are “lineSegment()” and “Polygon()”, ortheir equivalents. These are, of course, sufficent in the sense that any curved line or surface can be arbitrarrily well approximated by straight line segments or planar polygons, but in many contexts that is not enough. Such approximations often require large amounts of data to obtain satifactory smoothness, and they are awkward to manipulate. Then too, even with the the most sophisticated continous shading models, polygonaltechniques can resultin visually ojectionable images. Mach bands may be apparent at the borders between adjacent polygons, and there is always a telltale angularity to polygonal silhouettes. Hence many modelling systems are augmented by circles, spheres, cylinders, etc. and allow such simple primitives to be combined to form quite complex objects