RELATIONAL GEOMETRIC SYNTHESIS .1.

A novel object-orientated framework is proposed for 3D computer-aided design. Geometric objects including points, lines, curves, surfaces an d solids are defined and constructed in a system which captures and re tains many dependency relationships between objects, in a data structu re equivalent to a directed graph. The primary advantage is automatic updating of the model, preserving relationships, when an underlying ob ject is changed. Multiple types of parametric curves and surfaces and multiple levels of dependency are supported through a recursive progra m structure. Difficulties of surface-surface intersection and trimming are largely avoided, by provision of novel entities and relationships which permit construction of accurate and durable joins between surfa ce objects.