A raster-vector approach to GIS modelling: Natural Quality cartography

Abstract

The Surveying Department and the Transport Research Centre of the Polytechnic University ofMadrid (TRANSyT) cooperated on a research project where the generation of a Natural Quality map for the Peninsular Spain and Balearic Islands was one of the main outcomes. The main purpose of this cartography is to assist on the development of Environmental Reports for Strategic Environmental Assessments procedures.
Some local, regional, national and international organizations have been consulted in order to obtain suitable GIS thematic databases, including the recent Spanish infrastructure of spatial data (IDEE), the European Environmental Agency and the Spanish nature data bank.
The methodology begins with integration and normalization processes of data format (ESRI coverage), data accuracy (100 m), projection and datum (Lambert Azimuthal Equal Area – European Terrestrial Reference System 1989) with the aim of homogenising spatial data sets.
The generation of this Natural Quality map implies the combination of a significant number of maps, finally 12. This high number of variables resulted in a very complex methodology, which forced researchers to work with raster data instead of vector. Raster combination of data has proved to be an efficient way of simulating a vector approach for a high number of datasets. This resulted in a raster map which attribute data was a vector comprising information from 12 environmental variables.
Finally, a synthetic map was yielded through reclassification of the vector previously obtained. This map was assessed for consistency using various protected areas. The developed methodology, based on the used of GIS, has demonstrated the viability of implementation and convenience for future analysis.