Modeling and visualizing methods for real 3D geosciences model based on amended generalized tri-prism(GTP)

Abstract

By amending the auxiliary geometric primitive,diagonal,of generalized tri-prism(GTP) into tetrahedron,the inconsistentness of data organization and of geometric primitive in real 3D geosciences modeling as well as the geometric interstice in spatial operation were solved.The amended GTP model synthesized the merits of TIN,GTP and tetrahedron,and its constructing algorithm was simple and the spatial operation on it is seamless.The modeling process for R3DGM includes: ① to generate the constrained delaunay TIN(CD-TIN) of terrain according to the collar data of borehole and the outcrops of faults;② to extend each triangle of the CD-TIN downward to generate a GTP along the borehole tracks referring to the geo-inference rules;and ③ to convert the GTP model into tetrahedron model based on the smallest vertex identifier(SVID) method. The visualizing methods for arbitrary planar cutting,virtual excavation designing,virtual wandering and spatial inquiry on so constructed R3DGM were illustrated,and the effects out from the methods are shown with the real 3D integral modeling and 3D spatial operations for the underground geo-technical environment of CBD in Beijing being an example.