Full text: The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
Q.Y. LI 12 , D.Y. CAO 1 , X.D. ZHU 1 
1 Beijing Graduate School, China University of Mining and Technology, 100083, Beijing, Institute Road Ding 11, P.R.C. 
Tel: +86-010-62331409, e-mail: CDY@mail.cumtb.edu.cn 
2 Chinese Academy of Surveying & Mapping , 100039, Beijing, Beitaiping road 16, P.R.C. 
Tel:+86-010-68284094, e-mail: Liqy@.casm.ac.cn 
KEYWORDS: Mine, Geology, GIS, 3D, Data Model 
ABSTRACT: This paper discusses some 3D data model problems in Mine GIS. First, the status quo of GIS used in mines 
and mainly 3D data model are looked back. Then, the authors give some thinks about 3D data model in mine GIS. (1) 
Mine GIS model should be built on geology model. (2) Oriented-object vector model may have more advantage in mine 
application. (3) Curve surface representation is very important in 3D GIS. (4) 3D triangulate along curve surface is 
discussed to express nearly vertical or overturn fold curve surface. The procedure is (a) by manual interfering to divide 
sub-surface, (b) in every sub-surface, substitute 3D distance for 2D distance in Delaunay triangulating. The paper also 
discusses about nonuniformity of volume object interior. The authors think that 3D linear function and 3D ternary cubic 
function could be used as volume interpolation function. 
GIS(Geographic Information System) meets some 
difficulties in mine domain. It is because that the 
applications in mine are involved in many real 3D 
problems, but current commercial GIS platforms are 
absence of ability to deal with real 3D model. So, in many 
mines, the 3D model is simplified to 2D model, then, 
2D-GIS or 2D-CAD can be used. Some mine and geology 
software, such as Australian’s MINCOM, Canadian's 
Lynx, have developed mine design and exploration 
software, which can deal with 3D model and do 3D 
visualization. As far as 3D model is concerned, general 
GIS has fallen behind professional software of mine, 
geology and geophysics exploration. Although status of 
GIS in mine, geology is discomfiture, the authors think 
that in long views, 3D GIS will become basic platform of 
various 3D geographic spatial applications. Professional 
systems may be developed to general 3D GIS. Some 
professional system manufacturer may peel 3D function 
from their professional system, and add some general 
tools to suit other 3D geographic spatial applications. 
General GIS software manufacturers may develop 
2D/2.5D GIS to general 3D GIS too 
Model is an abstraction to real world. Data model is a 
bridge of real world to data world. Data model of an 
information system decides the data store structure and 
executable operation to the data. 3D data model is a 
kernel of 3D GIS and 3D CAD. The main ways of 3D data 
model are follows. 
3D objects are abstracted as an aggregation of 3D voxels. 
It expresses a point object by a voxel. A linear object is 
expressed by a string of voxels, which extend along one 
direction and the direction may change. A surface object 
is expressed by a collection of voxels, which extend 
along two directions and the direction may change. A 
volume object is expressed by a collection of voxels, 
which extends along three directions. 
The common advantage of voxels filling model is it has 
some ability to express uneven attribute in inside an 
object (including line, surface and volume object). The 
common disadvantages are as follows: (1) there is not a 
concise concept for an object, an object is expressed by 
an aggregate of voxels (exclusion of point object), (2) 
there is not distinct topological relation in object, 
however the relationship is very important in many spatial 
3D voxels may be cubic, regular cuboid, irregular cuboid, 
The research is supported by National Nature Science Foundation of China (SES:49771059) and Visitor Scholar 
tetrahedron, and so on. On voxel, 3D voxels fill model can 
be classed into next classes. 
(1) Regular Cuboid Voxels full Model (3D Raster Model): 
In 3D, the simplest voxel is regular cuboid voxels, just as 
equilateral square pixel in 2D. It is an extension of 2D 
raster in 3D. 
Fig. 1 Point, Li ne, Surface and Body in 3D Raster Model 
The advantage of 3D raster is simplicity in operation 
arithmetic. Especially, the data structure of unpacked 
standard voxel model is simple, standard and universal, 
(in 2D, the standard raster model is universal nearly). 3D 
raster model has some expressive ability for inner of body. 
Operation of overlay, buffer etc. can be realized easily in 
3D raster model. 
The disadvantages of 3D raster are (a) express for spatial 
object is imprecise, (b) it spends huge amount of memory 
units. When the resolving power improves, the quantity of 
memory unit expands as cubic quantity level. For 
example, in an exploration area of coal-field, length is 
2km,width is 1km, height is 0.5km, coal layer thick is 
1-3m. By 1m as voxel size, it needs 10,000,000,000 
voxels to express the 3D model. If the resolving power is 
increased 0.5m, it needs 80,000,000,000 voxels. Even so, 
it is still not enough to express coal layer. 
(2) Irregular Cuboid Voxels Full Model. In some 
application, resolving power in one direction has more 
importance than other direction. For example, in last 
coal-field exploration example, the resolving power in 
vertical direction has more importance than horizontal 
direction. In this case, the irregular cuboid voxel can be 
used. If using the voxel of length, width 10m, height 1m, 
it need 10,000,000 voxels

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