Abstract: A hybrid 3D spatial data model based on multiDEMs and quasi triprism volume (QTPV) is proposed. The model is composed of six primitive and six objects. The primitive elements are vertex, segment (edge, triangle side), triangle, secund quadrilateral, QTPV and DEM, respectively. And the objects are point, line, surface, volume, complex and spatial object, respectively. Data structures and topological relationship of the six primitives and two geological objects are designed in detail. Two modelling methods, based on sample points and interpolated points, are devised, separately. Two sets of simulation data and real borehole sample data are used to verify the prototype system developed in VC++. The results show that the proposed model has better abilities of describing the surface and the inner structure of spatial objects, which is suitable for 3D modeling in geological exploration field.

Key words: multiDEMs, quasi triprism volume, hybrid data model, geologic body modelling