Geo-information for monitoring land use from map overlay to object-structured noise reduction

Over the last 10 years, three different national geographical databases with data on land use and land cover have been developed in the Netherlands, all of which are to be updated at a frequency of once every four years. It was shown by means of a case study in the municipality of Soest that these multi-temporal databases could not be used to monitor changes in actual land use by using a simple GIS overlay technique. Most of the resulting changes were explained by the accuracy of the data sets themselves rather than by the `real world´ changes. An initial step in an object-structured approach has been developed, resulting in improved monitoring outcome for a detail of the Top 10 vector database. The method requires (empirical) threshold values for decision rules on overlap percentage, shape factor and reliability of thematic changes. A considerable part of the noise was filtered out at various levels of detail. The method will be further developed towards a monitoring tool for noise reduction, applicable to various spatio-temporal land use databases and data quality independent