Validating
Large-Area Land Cover Databases with Maplets
David M. Stoms
Point sampling methods traditionally used for assessing
accuracy of small-area thematic maps are less suitable for large-area,
lower resolution maps. Maplets, or detailed maps of small areas,
are proposed here as an alternative source of independent reference
data for accuracy assessment. As a land cover census instead of
a sparse sample of points, maplets can provide information on
the composition, heterogeneity, and accuracy of individual map
units, on boundary locational accuracy, and the spatial pattern
of errors in the large-area map. The techniques is illustrated
by a case study for a wildlife habitat map of southern California,
USA. Overall agreement between the maplet and the large-are map
was 63%. However, the total area of map units in which the label
agreed with the majority maplet class was 84%. This result suggests
that much of the "error" was actually generalization
rather than misclassification.