AN IMPROVEMENT OF 3D OO-SOLID MODEL 
DENG Nian-dong, HOU En-ke, ZHANG Zhi-hua 
Dept, of Geology and Environment Engineering, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China - 
(gissearch, houek, zhzhihua99)@ 163.com 
KEYWORDS: 3D GIS; Data Model; Data Structure; Spatial Modeling; Geology; 
ABSTRACT: 
The key issue of 3D geology modeling is the 3D data model. Because of discontinuity, complexity and uncertainty of distribution of 
3D geo-objects, some models only are suitable for regular, continuous and relatively simple spatial objects, and some are suitable for 
discontinue, complex and uncertain geo-objects, but some improvements on these models, such as, updating of model, maintenance 
of topological and seamless integration between models, are still to be made. The OO-Solid Model is an object-oriented 3D topologic 
data model based on component for geology modeling with fully considering the topological relations between geological objects 
and its geometric primitives. Comparatively, it accords with the actual requirements of three-dimensional geological modeling, but it 
has some defects, for example, the modeling sections are limited to the parallel and vertical section, still cannot adapt to nonparallel 
and folded sections, and don't fully consider the degradation of modeling primitives. These defects bring some negative effects on the 
integrality and effectiveness of organization of spatial data, spatial query, spatial analysis based on OO-Solid model. Aiming at the 
defects of the OO-Solid Model, OO-Solid model is modified. The component of this model is the basic element of the division of 
geological volumes. Primitives of OO-Solid Model are compartmentalized into node (cru-node, inner-node, isolated-node, 
reference-node, interpolated-node, and feature-node), arc (feature-line), polygon, component face (polygon face, component 
side-face, component up-down-face) and component. And conceptual model and logical model of OO-Solid model are redesigned. At 
last, data structure of OO-Solid model is designed. Above improvement not only benefits muti-source data compositing for modeling, 
upgrades auto-modeling, facilitates dynastic updating of geological model, also favors seamless integrating with other models, such 
as TIN. 
1. INTRODUCTION 
Data model is the key issue and foundation of 3D geological 
modeling and spatial analysis, and it’s important for realization 
of 3DGMIS. Predecessors have conducted a lot of research, and 
put forward facet models, such as, Grid model, TIN 
model(Barry, J., 1991; Victor J D., 1993), B-Rep model, 
Wire-Frame model, Series Sections model, and DEMs() model 
etc. as the representative of the model, and component model, 
such as, CSQ Voxel (Dai Wu-jiao,2001), Needle, Octree, 
Regular Block, TEN, Pyramid, TP, Geocellular, Irregular Block, 
Solid, 3D Voronoi, TP(ZHANG Yu, 2001), GTP(QI An-wen, 
2002; MAO Shan-jun., 2002) and OO-Solid model(HOU 
En-ke,2002) etc. as the representative of the model(WU Li-xin, 
2003). Because of discontinuity, complexity and uncertainty of 
distribution of 3D geo-objects, some models only are suitable 
for regular, continuous and relatively simple spatial objects, and 
some are suitable for discontinue, complex and uncertain 
geo-objects, but some improvements on these models, such as, 
updating of model, maintenance of topological and seamless 
integration between models, are still to be made. 
OO-Solid model, put forward by writer in 2002, is an object- 
oriented topological model based on sections. The OO-Solid 
Model is an object-oriented 3D topologic data model based on 
component for geology modeling with fully considering the 
topological relations between geological objects and its 
geometric primitives, Comparatively, it accords with the actual 
requirements of three-dimensional geological modeling, but it 
has some defects, for example, the modeling sections are 
limited to the parallel and vertical section, still cannot adapt to 
nonparallel and folded sections, and don't fully consider the 
degradation of modeling primitives. These defects bring some 
negative effects on the integrality and effectiveness of 
organization of spatial data, spatial query, spatial analysis based 
on OO-Solid model. Aiming at the defects of the OO-Solid 
Model, this model is modified; conceptual model, logical model, 
and data structure of OO-Solid model are redesigned. 
2. MODELLING THEORY OF OO-SOLID MODEL 
The component is the base modeling unit of OO-Solid model, 
which defined by fore-component-polygon, mid-component- 
polygon and post-component-polygon. Mid-component- 
polygon is identified by the profile of section for spatial 
geo-objects, and fore-component-face and post-component-face 
are inferred from geological staff with setting equidistant 
between mid-component-face. The modeling ideas are shown in 
document written by Hou En-ke (Hou En-ke, 2002). The 
primitives of component includes node, arc, feature line, 
component polygon and component face. OO-Solid model can 
consider the topology of geological objects, and can be fully 
taken into account the limited of geological data and the needs 
of interactive inference and interpretation of geological staff, 
and benefit constructing the complex geological model(Hou 
En-ke, 2006).. 
Although compared with other 3D geological model, OO-Solid 
model have many unique advantages, it need be perfected and 
rectified in some respects, such as auto-search for topological 
relationship and taking geological model constructing and 
dynamic updating into account. 
3. MODIFICATION OF OO-SOLID MODEL 
3.1 Modelling primitives of OO-Solid Model 
Arming at these defects of OO-Solid model, the primitives are 
redesigned as following six primitives.: