Formal Description of 3D Semi-tunnel Component

Formal description is an abstract mathematical description based on the mathematical model, and it is a theory foundation of three-dimensional (3D) modeling and system development. The semi-tunnel is component which constructs 3D tunnel model as research object, using Object-oriented approach and the collection operation for specific ways, by analyzing the construction elements of semi-tunnel, all modeling elements of semi-tunnel are strictly defined and made formal description by utilizing the theory of topology. Then, based on the formal description of modeling elements, the formal description of semi-tunnel is expressed, it is easier to design and program the semi-tunnel. According to the formal description of semi-tunnel, it also simplifies the construction of 3D tunnel network model, and facilitates the spatial analysis and query.