ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
162 
RESEARCH ON INFORMATION AUTOMATIC GENERALIZATION WITH VARYING MAP SCALE 
Yuanhui LI 1 Dan LIU 2 Yifan LI 3 
1 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel:86-411-4729297 
E-mail: yuanhuilee@hotmail.com 
2 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel:86-411-4729297 
3 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel:86-411-4729297 
E-mail: yifanli@163.net 
KEY WORDS: Information Automatic Generalization, Varying Map Scale, Topological Relation 
ABSTRACT 
The change of spatial topological relation and how to recover these topological relations through studying the change of objects’ 
geometrical relation are studied, twelve approaches have been given to resolve 12 kinds of geometrical deformation in map 
generalization. 
1. INTRODUCTION 
Along with the development of GIS in various application field, 
the existing GIS data processing technique can not meet with the 
requirements of space times and information society, the 
important problem is that GIS can not resolve the increase and 
decrease of information when data on vector space change with 
scale. Namely, the problem of extraction and recovery of space 
information with the varying map scale. The varying map scale 
GIS is a kind of information processing techniques for extraction 
and recovery of GIS space information in accordance with the 
scale, which the information of spatial objects increases or 
decreases automatically along with the change of the scale in a 
certain region, based on a big database. Varying map scale 
technique includes map automatic generalization and information 
automatic generalization. Many scientists had made a detail 
definition and analysis for map automatic generalization and 
gained mature results, But Information automatic generalization 
is emerging, which mainly studies the change of spatial objects’ 
topological relation, geometrical relation and attribute relation in 
information extraction of GIS when map automatic generalization. 
This paper mainly research into the change of spatial topological 
relation and how to recover these topological relations through 
studying the change of objects’ geometrical relation. 
2. THE CHANGE OF INFORMATION IN MAP AUTOMATIC 
GENERALIZATION 
As all known, the following means influence the geometrical 
relation of map in map automatic generalization: 
1. Selection of diagnostic object sign 
2. Displacement 
3. Distortion 
4. Merging 
So, we can get 12 kinds of change in map generalization.: 
1. Reshape polygon to counter self-coalescence 
2. Reshape two polygons to counter coalescence 
3. Displace polygon to counter coalescence 
4. Select subset of points to counter congestion 
5. Amalgamate polygons to counter coalescence and 
congestion 
6. Partial area collapse to counter self-coalescence 
7. Area conversion to counter congestion 
8. Typification in sets of polygons to counter congestion 
9. Dissolution in a subdivision to counter imperceptibility 
and congestion 
10. Exaggeration amidst other features 
11. Exaggeration in a subdivision 
12. Typification of a polygon to counter self-coalescence 
3. INFORMATION AUTOMATIC GENERALIZATION WITH 
VARYING MAP SCALE 
Points are independent objects in topological data structure and 
they can be connected each other to form a line. Line is 
constituted by a series of connected points, starting with a start 
point and ended by a terminal point. String is a line of one or 
more polygons, also called arc or edge. Node is the intersectant 
point or the terminal point of line or string. A polygon is composed 
by a outer ring and zero to more inner rings, and a ring is 
composed by one or more strings. This shows that the essential 
geometrical structure in topological data is line, so we should 
generalize line, then smooth it and process consistency check. 
Now we discuss the change of topological data based on 12 
kinds of deformation in map generalization. 
1. Deformation of single polygon 
We only need change the deformation of the line related to 
this polygon. A SHAPE polygon q ^ _ ( u v ( 5 )) is given, 
make a polygon S*(s, t) through these lines, t is the parameter of 
the SHAPE polygon, then s * (s, t) = (U(s, t), V(s, t)) and 
U(s,t i ) = u l (s),V(s,t i ) = v i (s) 
Vf e [0,1] .make S(s,t)=(x(s,t),y(s,t),z(s,t)),so 
S(s, t) = P(t) + a(s, t)x(t) + b(s, t)y(t) 
a(s,t)and b(s,t)isdefined as follows: 
Let 
m x = minU(s,t),m 2 = ma xU(s,t) 
m, = min V(s, t),m A = max V(s, t) 
sc x 
m 2 - w, 
sc., 
-m 2 
|/ 4 (0-/ 3 (0| 
then