An adaptation of the GAIA visualization method for cartography

Dimensionality reduction has always been important within disciplines that focus on visual representation of multivariate information. In the case of cartography this has been achieved several times by the use of statistics charts and diagrams, but these are limited in the number of components that can be combined in a single glyph. On the other hand, Multicriteria Decision Aid (MCDA) has developed tools to visually represent multidimensional information, yet these cannot be directly applied on geographical maps. In this paper we present a way to adapt the GAIA visualization tool to the representation and comparison of multicriteria profiles on maps. The process involves the use of a Principal Component Analysis (PCA) and the conversion of its result by applying a HSV color chart. We illustrate this process by applying it to two case studies: an evaluation of the Human Development Index (HDI) and of the Environmental Performance Index (EPI) of the European countries.