ABSTRACT
Geometric modeling techniques in computer graphics have evolved significantly as the field matured and attempted to portray the complexities of nature. Earlier geometric models, such as polygonal models, patches, points, and lines, are insufficient to represent the complexities of natural objects and intricate man-made objects in a manageable and controllable fashion. Higher-level modeling techniques have been developed to provide an abstraction of the model, encode classes of objects, and allow high-level control and specification of the models. Most of these advanced modeling techniques can be considered procedural modeling techniques: code segments or algorithms are used to abstract and encode the details of the model, instead of explicitly storing vast numbers of low-level primitives. The use of algorithms unburdens the modeler/animator from low-level control, provides great flexibility, and allows amplification of their efforts through parametric control: a few parameters to the model yield large amounts of geometric detail (Smith [1984] referred to this as database amplification). This amplification allows a savings in storage of data and user specification time. The modeler has the flexibility to capture the essence of the object or phenomena being modeled without being constrained by the laws of physics and nature. He can include as much physical accuracy, and also as much artistic expression, as he wishes in the model.
