Cartographical methodologies in calculating spatial indicators supported by GIS, accuracy and errors on choropleth maps: applications in demographic and land use indicators

Abstract

Within a decade, the dimensions of cartographic communication have multiplied due to the developments in geο-informatics. It has also been noted that the transformation of the traditional cartographic methodologies into special aspects of digital communication, supported by Geographical Information Systems, has led to new techniques that have been considered to be effective methodological tools in the field of spatial development. However, the current methodologies of spatial analysis and specially those who are based on the use and representation of spatial indicators include the risk of cartographical and methodological errors. These errors are due to parameters οf cartographical accuracy, as well as to parameters in the calculation of the indicators. A typical example of these concerns the choropleth maps (spatial density maps). The main goal of the study is the compilation of an alternative proposal, concerning cartographic methodologies of the calculation of spatial indicators supported by Geographical Information Systems. Two groups of indicators, simple but typical and representative of their construction methods, are selected. The first group includes two spatial indicators, quite widespread in the field of demographic analysis: "Built-up areas referred on statistical units" and "Population density referred on the pure built-up areas". The second group includes two indicators related to land use: "Analytical land cover referred on spatial units" and "Agricultural land per capita referred on spatial units".