ISPRS, Vol.34, Part 2W2, "Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
Foundation of Education Ministry Higher Education Key 
Fig. 2 Irregular cuboid voxel express ore layer 
(3) Octree Model: Octree model is developed to get over 
the disadvantage of equal size cubic model. It is an 
extension of 2D quad-tree in 3D. Octree model 
recursively subdivide a 3D volume object into eight 
octants. If the eight octants belong to the same object, the 
volume dose not need continue subdivide, else the 
octants belongs to different objects, the octants should be 
further subdivided to smaller octants, until the 8 
sub-octants belongs to a same object or reached a given 
resolution. Octree is a 3D raster model which can be 
continuously bisection subdivided. It is a variation of 3D 
standard raster model. Octree model greatly reduces 
storage quantity from standard 3D raster model. 
Kavouras and Masry(1 987), Li (1996) use octree model to 
express geology model. Guo (1993), Han (1992) used 
octree to express underground mine 3D objects. 
(4)Tetrahedron voxel fill model: This model partitions the 
space into a lot of tetrahedrons, which adjoin but not 
overlap, just as triangulation in 2D, using the collection of 
tetrahedron to express spatial object. The characteristic 
of this model is that the coordinates of 3D sampling points 
can be used to 3D interpolation and visualization. The 
adjacency of tetrahedron can represent topology relation 
of spatial object. Pilouk(1994), Chen(1994) have done 
research work to tetrahedron voxel fill model. 
Tetrahedron parting to a volume space is a base of fitting 
volume function for volume Interpolation that will mention 
in later 3.4 
2.2 CONSTRUCTION SOLID GEOMETRY MODEL 
It is also called CSG model. The essential thought is that 
for simple geometry object (such as cubic, ball, cylinder, 
cone) by regular collect operation (such as ‘and’, ‘or’, 
‘difference’) and rigid body geometry transform (‘move’, 
'revolve') to form an ordered bintree (it is called CGS 
tree), to express complicated object. The operation is to 
Laboratory. 
adjoining son leaf node only. Every sub-tree is result of 
composition and transform to its two son-nodes. Root of 
the tree represents the whole object. This method is 
widely used in mechanical and architecture, Li (1994) has 
used it in 3D GIS to express 3D architecture group. 
2.3 3D VECTOR MODEL 
It is extension of 2D point-arc-polygon model in 3D. It 
abstracts 3D world as collection of 3D point, arc, surface, 
and body. It is very similar to 3D boundary model in 3D 
CAD. The advantages of 3D vector model are (1) precise 
express for spatial object, (2) data quantity small, (3) 
topological relationship of spatial objects can be 
expressed obviously, so the spatial inquire, topological 
inquire, adjacency inquire, net analysis can be realized 
easy. The disadvantages are (1) complicated in operation 
arithmetic, (2) poor ability to express unevenness of 
volume interior, (3) difficulty in overlay and buffer 
operation. 
M.Molennar(1990,1992), D.Fritsch (1995, 1995) studied 
3D vector model from GIS science, proposed 3D vector 
map’s format data structure. Chen & Guo (1997,1998) 
have studied in 3D geometry elements topology from 9 
intersection model. Li & Cao (1996, 1997, 1998), from 
application in mine and geology, have proposed in (1) 
‘Five group relation’ to express 3D object topologic 
relationship. The five group relation are: © Node - 
BeginEdges - EndEdges , ©Edge - BeginNode - EndNode 
- Cycles , © Cycle - Edges- InnerAdjacentFace , ©Face 
- OutCycle - InnerCycles - PositiveAdjoinPolyhedron - 
NegativeAdjoinPolyhedron, © Polyhedron - Faces, (2) 
'Introducing surface - dividing body’ as a way to dynamic 
build and maintain the 3D topology, (3) ‘One surface with 
three layers’ to deal with contradiction of integrality of 
surface with difference of both side (positive, negative) 
adjoin polyhedron, (4) 3D body function interpolation in 
body inside. 
Fig.4 Vector Model (Point,Line,surface,Volume ) 
2.4 3D OBJECT ORIENTED MODEL 
Object-Oriented is a modish topic in software industry of 
90s of 20 century, Gong & Xia (1998) proposed Object - 
Oriented 3D Data model, which integrated vector and 
raster. They have abstracted 13 classes of spatial object. 
They especially emphasize to introduce of digital surface, 
section and column. 
Huo (1996) thinks that there are two models GIS data 
model, base on region and base on object. The first model 
(base on region) emphasizes on spatial - temporal 
distribution of some geography attribute of the spatial 
object. It is an abstraction of some essence to reality 
world. It emphasizes on continuance of temporal and 
spatial. From system view, this only has some structure, 
but has not total function, it emphasize on part or local. 
The second (base on object) emphasize on system total