Integrating land cover data with different ontologies: identifying change from inconsistency.

Spatially coincident land cover information frequently varies due to technological and political variations. This is especially problematic for time-series analyses. We present an approach using expert expressions of how the semantics of different datasets relate to integrating temporal time series land cover information where the classification classes have fundamentally changed. We use LCMGB and LCM2000 as example data sets because of the extensive object based meta-data in the LCM2000. Inconsistencies between the two datasets can arise from random, gross and systematic error and from an actual change in land cover. Locales of possible land cover change are inferred by comparing characterisations derived from the semantic relations and meta-data. Field visits showed errors of omission to be 21% and errors of commission to be 28%, despite the accuracy limitations of the land cover information when compared to the field survey component of the Countryside Survey 2000.