A 3-dimensional Data Model for Visualising Cloverleaf Junction in a City Model

Seldom research work has been done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its main body is bestraddle in air, and has aerial intersections between its parts. This complex feature made cloverleaf junction quite different from buildings and terrain, therefore, it is difficult to express this kind of spatial objects in the same way as for buildings and terrain. In this paper, authors analyzed spatial characteristics of cloverleaf junction, proposed an all-constraint points TIN algorithm to partition cloverleaf junction road surface, and developed a method to visualize cloverleaf junction road surface using TIN. In order to manage cloverleaf junction data efficiently, the authors also analyzed the mechanism of 3DCM data management, extended BLOB type in relational database, and combined R-tree index to manage 3D spatial data. Based on this extension, an appropriate data structure for cloverleaf junction in 3DCM is proposed. * In Proceedings of International Workshop on Urban 3D/Multi-media Mapping, Shibasaki, R. and Shi, Z. (eds.), 30 September – 2 October, Tokyo: 203-208.