JUNCTION MODELING IN VEHICLE NAVIGATION MAPS AND MULTIPLE 
REPRESENTATIONS 
A. O. Dogru® and N. N. Ulugtekin® 
® ITU, Civil Engineering Faculty, 34469 Maslak Istanbul, Turkey - (dogruahm, ulugtek)@itu.edu.tr 
TS — PS: WG 1V/3 Data Generalization and Data Mining 
KEY WORDS: Cartography, database, generalization, navigation, automation. 
ABSTRACT: 
Generalization is certainly one of the most important current issues in cartography, with particular emphasis being placed on its 
automation. This paper considers the automation of generalization applied to road networks primarily urban roads. In this context car 
navigation is considered as main subject. As Timpf et al. (1992) stated car navigation require data at a wide range of scales and at 
different levels of abstraction so a case study on map design for car navigation is done in this work 
Navigation Key problem areas are parts of the network where a topological change occurs based on scale. For example, single or 
multiple lane representation of the roads and junctions can cause many problems to both the navigating user and the cartographer 
who designs the map. So these different representations of the roads are examined in this study. Each possible representation of the 
highways and its junctions is considered as different representational level in the scope of multiple representational databases 
(MRDB). Fundamentals of the MRDB are developed for the urban road data, where the significant transformations are identified 
and tracked. Generalization tools that can be used for obtaining multi-scale representations from the base database are defined in this 
paper. 
1. INTRODUCTION 
1.1 General 
Technological developments occurring in time affect 
cartography just as the other disciplines. Especially 
developments in computer technologies and the use of the 
Geographical Information Systems (GIS) made significant 
changes in map production and generalization processes. 
Managing full automation of these processes has become one of 
the main tasks of cartographers and related researchers. 
Fundamental studies were done from the beginning of the 1960s 
up to now by Tópfer and Pillewizer (1966), Douglas and 
Peucker (1973), Shea and McMaster (1989), and etc. on these 
subjects. In most of these studies different algorithms, which 
are used for the automation of map production (especially 
generalization), were developed. However, in this period, 
studies were done not only on algorithm development but also 
on acquisition, storage, and maintenance of spatial data. 
Multiple Representational Database (MRDB) is one of the 
significant products of these attempts. 
Developments mentioned above have affected automobile 
industry so car navigation systems recently became one of the 
prime parts of this market. As a result, use of maps by the driver 
has evolved from the classical roadmaps to the screen maps 
while travelling. 
1.2 Aim of This Work 
This work is a product of a continuous study that aims to 
produce maps for navigation purposes in terms of MRDB. Car 
navigation is considered as the basic case among the different 
navigation concepts and different levels of representations of 
the highways, which will be displayed on in-vehicle devices, 
are examined. The problems that occur on the problematic parts 
of the road networks, junctions, while finding shortest path and 
optimal route because of topology are determined then optimal 
representations for any scale are proposed. Meanwhile the 
fundamentals of an MRDB for navigation maps are formed in 
.this work. This work is an approach for solving a specific 
problem occurring in navigation map production process by 
using MRDB. 
2. CARTOGRAPHY AND GENERALIZATION 
Cartography is the science, art and technology of making, 
using, and studying maps. As a result of the technological 
developments, significant changes on cartographic process 
occurred in time. Digital map production became as important 
as classical methods by the help of computer technologies. 
Moreover Internet brought a new perspective to the cartography 
so Web cartography became an important and discussing 
subject for cartographers (Kraak, 2002). Nowadays, mobile 
mapping technologies and methods, which aim to design maps 
for mobile devices such as mobile phones or Personal Distiller 
Assistants (PDA), introduced mobile cartography or small 
display cartography. 
Generalization, which is considered as the spatial equivalent of 
simplification by Bertin (1983), can be defined as selection and 
simplified representation of detail appropriate to the scale 
and/or purpose of a map (ICA, 1973). It is one of the most 
important and problematic subjects of cartography. It is 
problematic because, although the widespread use of GIS and 
spatial databases and the need for visualization of spatial data 
over a huge range of scales has stimulated much research and 
development effort in this direction, success in automation of 
the generalization progress has been limited. There are several 
definitions for generalization from different experts and 
associations but it is obvious that most of them consider 
generalization as one of the most difficult task of cartographer. 
244 
Internai 
Spatial 
steps: .? 
two m 
general 
represei 
consists 
1997). 
preproc 
other h: 
compor 
so it is 
art. As 
in the t 
geograr 
product 
2.1 Ge 
Studies 
concept 
process 
should 
while d 
step. G 
questiot 
or proc 
these oj 
and Mc 
while a 
operato 
as sin 
amalgar 
merging 
operato; 
transfor 
Issues ' 
(1997) « 
infrastrı 
2.2 Ne 
General 
product 
concept 
the mo: 
2000). . 
the mar 
and qua 
the fact 
(1978). 
the hun 
process 
As it i 
Especia 
the proc 
the ger 
mathem 
"charac! 
coordin: 
words, 
relation: