Virtual reality based solid modeling

This paper presents an approach for intuitive and precise solid modeling in virtual reality environments. It develops a hierarchically structured and constraint-based data model to support object modeling, and uses automatic constraint recognition and precise constraint satisfaction to assist object manipulation. The proposed data model integrates a high-level constraint-based model, a mid-level hybrid solid model, and a low-level polygon model for object definition, object creation, and real-time interaction respectively. Constraint-based modeling operations and typical locating methods are also provided in the paper with details.