The most commonly assessed errors in maps are characterized as
classification or thematic errors. However, the effects of positional
errors, which includes both rectification errors and GPS errors, on
classification accuracy and inferences based on classifications are
often ignored. As the label suggests, rectification error results from
imperfect rectification of imagery to the coordinate system. Congalton
(2007) asserts that topography is the primary factor affecting
rectification accuracy and that rectification accuracy is an integral
component of classification accuracy. Rectification error is typically
quantified as the root mean square distance between known ground
point locations and their locations in the rectified imagery