A Structural Approach to Representation of 3D-objects

In this paper a structural method for 3D object modelling and representation is presented. The process of construction of 3D objects is realized by modelling 2D-patterns and extruding them by means of the defined operations: translational, rotational and generalized extrusion (sweeping) operations. Modelling of 2D-patterns is performed by grouping primitives into 2D features. All the presented extrusion operations are defined on the basis of the shape feature languages (1),(2),(3),(10). Each extrusion operation creates a volume subtracted from or added to a solid in order to obtain a 3D feature. Composition of any of such extrusion operations allows grouping of 3D features into 3D-objects with complex, classifiable structures. Parallel to the modelling process the hierarchical graph representation of an object is created which could then be used for feature recognition (6),(7),(9) and object analysis. Using the presented method one can model the machinning of a wide class of prismatic components. The presented method for 3D object representation is then compared with other similar approaches for representation of a 3D object (12), (13).