Geoscience Reference
In-Depth Information
12
CHAPTER
An Error Matrix Approach to Fuzzy Accuracy
Assessment: The NIMA Geocover Project
Kass Green and Russell G. Congalton
CONTENTS
12.1 Introduction...........................................................................................................................163
12.2 Background...........................................................................................................................164
12.3 Methods ................................................................................................................................165
12.3.1 Classification Scheme...............................................................................................166
12.3.2 Sampling Design ......................................................................................................166
12.3.3 Site Labeling.............................................................................................................167
12.3.4 Compilation of the Deterministic and Fuzzy Error Matrix.....................................168
12.4 Results...................................................................................................................................168
12.5 Discussion and Conclusions.................................................................................................170
12.6 Summary...............................................................................................................................171
References ......................................................................................................................................171
Appendix A: Classification Rules..................................................................................................172
12.1 INTRODUCTION
As remote sensing applications have grown in complexity, so have the classification schemes
associated with these efforts. The classification scheme then becomes a very important factor
influencing the accuracy of the entire project. A review of the recent accuracy assessment literature
points out some of the limitations of using only an error matrix approach to accuracy assessment
with a complex classification scheme. Congalton and Green (1993) recommend the error matrix
as a jumping-off point for identifying sources of confusion (i.e., differences between the map
created from remotely sensed data and the reference data) and not simply the “error.” For example,
the variation in human interpretation can have a significant impact on what is considered correct.
If photographic interpretation is used as the source of the reference data and that interpretation is
not completely correct, then the results of the accuracy assessment could be very misleading. The
same holds true even for observations made in the field. As classification schemes become more
complex, more variation in human interpretation is introduced (Congalton, 1991; Congalton and
Biging, 1992; Gong and Chen, 1992; Lowell, 1992).
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