KARTOGRAFISCH TIJDSCHRIFT
200I-XXVII-I
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Map Projection Selection. The American Cartographer Vol.
16, nr 1, pp. 29-38.
Richardus, P. R.K. Adler (1972), Map Projections for geo-
desists, cartographers and geographers. Amsterdam: North-Hol-
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berlin G.C. Guptil (1995), Elements of Cartography. 6th
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Snyder, J.P. (1987), Map Projections - A working Manual.
Washington: U.S. Geological Survey Professional Paper 1395.
Summary
E. Eleere M. Storms - Selection of map projections in GIS envi-
ronment
Keywords: map projection, gis, research
Reasearch, currently heing executed at the University of Utrecht,
aims at simplifying the choice of a map projection in a GIS
environment. The goal is to base the selection on the metrical
quality of the projection. This quality is determined by the so
called 'circle method'. There has to be a selection procedure
starting with only a small number of projections, using only the
projections with the highest accuracy. This research is meant for
small scale mapping of relatively large areas at a limited size of
representation. The selection consists ofconformal, equivalent and
equidistant projections plus some which are neither equivalent nor
conformalThe circle method compares distances between points
on the maps to the distances between those points in reality. The
deformation value of a certain point says something about the
accuracy ofthat point in relation to the other points on the map.
That is also the dijference with the method of Tissot, where the
distortion ofa point is shown in relation to the centre of the map.
Nevertheless, the deformation values of the circle method depend
on the chosen points in the map. Twenty projections were tested
using a coordinate file of Europe. Of these twenty projections the
equidistant Postelprojection has the lowest deformation values. In
general the differences between the projections are very small. The
results of this research are only validfor this specific coordinate file
of Europe. Further research will be done for different areas with
other sizes and shapes. Also the dividing line between small and
large scale maps - important because the projection choice is less
relevant for large scale maps - has to be found with help of the
circle method.
Resume
E. Heere M. Storms - Choix de projections cartographiques
dans le cadre du SIG
Mots-cles: projections cartographiques, sig, recherche
L'objectif de ces recherches, actuellement en cours l'Universite
d'Utrecht, est de simplifier le choix de projections dans le cadre du
SIG, en se basant sur La qualite metrique des projections, definie
par la dite "methode du cercle". Ilfaut commencerpar un nombre
limite de projections de grande precision, pour l'usage des cartes a
petite echelle couvrant des zones geographiques relativement
etendues. Ont ete choisies des projections confiormes, equivalentes,
equidistantes et encore certaines autres ni equivalentes, ni
confiormes.
La methode du cercle compare les distances entre les Localisations
sur la carte avec Celles dans la realite et la valeur de la
deformation mesuree indiquera La precision de la carte entre les
localites, la dijference de la methode de Tissot, etablissant cette
reference par rapport au centre de La carte. Toutefois, les
defiormations ainsi mesurees sont en fonction du choix des
localisations.
Vingt projections ont ete testees dans un fichier contenant les
coordonnees geographiques de TEurope et la deformation
minimale a ete enregistree pour la projection equidistante de
Postel. En general, les dijferences entre projections sont tres
reduites. Les resultats sont uniquement valables pour ce fichier
specifique des coordonnees en Europe et d'autres recherches seront
entreprises pour d'autres regions, de tailles et de fiormes dijferentes.
II faut egalement trouver par ladite methode la ligne de partage
entre cartes petite et grande echelle pour ce dernier le choix
d'une projection est moins important.
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