The evaluation and comparison of thematic maps derived from remote sensing

The accuracy of thematic maps derived from remote sensing is often viewed negatively. This reflects difficulties in mapping but also issues connected with accuracy evaluation targets and assessment approaches. This paper focuses on the latter issues suggesting that the widely used target accuracy of 85% may often be inappropriate and that the approach to accuracy assessment adopted commonly in remote sensing can be pessimistically biased. Problems are also encountered in the comparison of thematic maps, hindering research that seeks to increase classification accuracy which is often based upon evaluations of the accuracy of maps derived from a set of classification algorithms. It is hoped that a greater awareness of the problems encountered in accuracy assessment and comparison may help ensure that perceptions of classification accuracy are realistic and fair.