Research on the terrain-objects oriented DEM and its preliminary application

Though most of nature terrains, such as flat plains and hills, can be represented well by traditional grid-based DEM, a lot of Nature-artificial Terrains (NATs), like typical terraces in loess plateau in northwest China cannot be represented well and efficiently directly by grid-based DEM. Therefore, the concept, data model and data structures of a new Terrain-objects Oriented DEM called TODEM are presented in this paper. The classification of terrain objects and their encapsulation are discussed in detail. The main attributes and methods of several core classes of TODEM, such as SubTIN, GlobalGrid, Terrace, and TODEM, are also described in details. The methods of constructing TODEM by embedding the SubTINs into GlobalGrid seamlessly are also put forth and used to represent the typical NATs like terraces in loess plateau successfully in our case study. The results of the case study show that the planar and vertical shapes of terraces can be represented well and visualized realistically by the TODEM. The methods of constructing TODEM by using feature lines of NATs are feasible.