summaries
78
KT 1989.X V.l
M.C.S. Wopereis and A.K. Bregt - Complexity measures for
choropleth maps: a comparison
The complexity of a choropleth map has an important in-
fluence on its readability. Six map complexity measures
(aggregation index, compactness index, Muller's complexity
index, fragmentation index, boundary index, size disparity
index) that are given in cartographic literature are presented
in this study. Correlation coefficients between these indices
are calculated using 90 different maps. It is shown that most
of the measures are highly corre/ated and therefore
redundant.
Visual judgement of 13 maps by 28 subjects shows that four
indices (aggregation index, compactness index, fragmentation
index, boundary index) can serve as reliable indicators of
map complexity. As a result each of these measures can be
used to compare pattern complexity among different maps.
The fragmentation index seems to be the best choice in view
of its simplicity and ease of calculation.
L.W. van der Velde and J.H. Wiechers - Development of a
computer-assisted route finding System
The computer-assisted route finding System described in this
article is a System which constructs a route between a Storf
ing object indicated and one or more objects of destination.
With this system it is made possible to provide tailor-made
information to the individual user. It is possible to couple the
route constructed with information about that particular
route (e.g. travel time and distance) and about the objects to
be visited. Attention is paid here to the programming lan-
guage used, the method of searching the shortest route and
the construction of the database. Finally, some possible ap-
plications of the route finding system are discussed.
L. Heres - DEMETER: Digital road maps for car navigation
Systems
The last decade has shown an increasing number of activities
in the field of car navigation and information Systems,
thanks to the availability of cheep and powerful microproces-
sors and the development of the Compact Disc. In the most
complete Systems 5 different functions can be distinguished:
address conversion, route search, driver guidance, vehicle lo-
cation and position visualization. These functions have
different information requirements that vary from the need
for street names to the need for information about traffic
restrictions. Common is the need for a good knowledge of
the geometry of the road network. The route search function
also needs a good topological representation.
Different activities exist to create digital road data bases that
are suitable for car navigation Systems. One of these activi
ties is the Demeter project, the aim of which is a certain
degree of standardization.
Digital road databases can be considered as a special kind of
maps, their creation as a special kind of mapping and the
speciality that occupies itself with them as a special kind of
cartography; a kind of cartography that offers new
challenges.
M. de Graaf and K. Witteveen - North Sea Project
In October-November 1988 the Norwegian survey vessel
Lance made a voyage across the North Sea, with six different
Electronic Chart Display and Information Systems (ecdk)
aboard. This was a part of the test, called 'North Sea
Project', a result of the Cooperation between the Hydro
graphie Services around the North Sea, including the Canadi-
an Hydrographie Service, and ecdis manufacturers.
The aim of this project was to test the Systems themselves
and the iho-specifications on ecdis. The results of the test
shall be used for further development of ecdis.
This article reviews the six Systems aboard and some ques-
tions about the cartographic aspects of the Systems aboard
and ecdis in general.
H.M. Bosma - Graphic Software on Apple Macintosh
The characteristics of the Apple Macintosh personal Com
puters are discussed first. After that some graphic Software
pass in review: programs for painting and drawing, business-
graphics, desktop Publishing, cad and special cartographical
programs. In the discussion of Software for painting and
drawing much attention is given to the characteristics of
raster-drawing and vector-drawing in particular.
M. W.H. van Elk - Free Hand, also for cartographers
In the field of the automated produetion of small scale
thematic maps there are still many obstacles to overcome that
deal with the manipulation of the Software, the user-
friendliness of the operating Systems and the quality of the
Output. Userfriendly Systems are on the market, but until
recently they were not compatible with the ms-dos
environment.
In 1988, FreeHand, a new graphic design Software package,
became available for the Apple Macintosh. In this article the
author describes the use and extended possibilities of this
Software.
Manipulating FreeHand is very easy, and although not spe-
cially developed for cartographic purposes, point-, line- and
area-symbols can easily be designed and stored in a menu.
There are no restrictions like in the usual cartographic Soft
ware; changing a once defined symbol in FreeHand only
