AUTOMATIC MAPPING OF _LAKES_FUK _SMALL-SCALE_ MAPS. 
USING DIGITAL LANDSAT IMAGERY 
CARTOGRAPHIE AUTOMATIQUE DES LACS POUR LES CARTES A PETITE ECHELLE 
UTILISANT LES IMAGES NUMERIQUES LANDSAT 
by 
E.A. Fleming 
Surveys and Mapping Branch 
Department of Energy, Mines and Resources 
Ottawa, Canada 
ABSTRACT 
In much of Canada lakes predominate the landscape, but the carto- 
graphic generalization employed in producing maps at scales of 1:500 000 and 
1:1 000 000 often fails to capture this aspect of the terrain. 
A more realistic rendition of the hydrology can be obtained if the 
conventional cartography of drainage is combined with lakes as imaged on Land- 
sat MSS. Thematic extraction of the water using geometrically corrected digi- 
tal imagery has proved feasible for this purpose. 
RESUME 
Sur la plus grande partie du territoire canadien, les lacs sont la 
principale caractéristique du paysage, mais la généralisation cartographique 
employée dans la production des cartes aux échelles de 1:500 000 et 1:1 000 000 
néglige souvent de démontrer cet aspect du terrain. 
Une traduction plus réaliste de l'hydrologie peut être obtenue si la 
cartographie conventionnelle représentant le réseau hydrographique est associée 
aux lacs tels qu'ils apparaissent sur les images multi-spectrales prises par 
Landsat. L'extraction thématique de l'eau à partir d'images numériques corri- 
gées au point de vue géométrique est um moyen d'en arriver aux résultats 
souhaités. - 
INTRODUCTION 
  
In much of Canada, lakes predominate the landscape. They vary in form from 
intricate, island-filled lakes of Canadian Shield to the smoother outlines of 
lakes in open country. The prairie wetlands are covered with intermittent 
lakes; the muskegs and tundras of the north are dotted with small ponds.  Under- 
standably, lakes and drainage form an important part of the cartography of 
Canadian maps, and as water becomes an increasingly important resource, their 
mapping takes on new significance. 
Each area and each map scale presents its own cartographic problems. An an 
alternative to the conventional portrayal of water areas on small scale maps of 
the scales 1:500 000 and 1:1 000 000, the use of Landsat-imaged water areas is 
being explored. These methods could lead to a more accurate portrayal of the 
terrain at small scales and could at the same time provide a digital data base 
for computing water areas. 
CONVENTIONAL CARTOGRAPHY 
Topographic maps are currently compiled at a scale of 1:50 000 in Canada. Where 
965