Accuracy assessment of wetland boundary delineation using aerial photography and digital orthophotography

We compared the horizontal accuracy of forested wetland boundary delineatio ns obtained from large-scale, natural color aerial photography against deli neations obtained from "heads-up" digitizing of digital orthophotography. T he absolute value of the mean (+/- SD) distance between the field-derived " true" wetland boundary location and the orthophotograph-derived wetland bou ndaries was 3.4 +/- 3.4 m and was slightly more accurate than the mean dist ance between the "true" boundary and the aerial-photo-derived wetland bound aries (4.5 +/- 4.0 m). Field visitation increased the accuracy of delineati ng wetland boundaries, and the majority of wetland edges-both orthophotogra ph- and photo-derived-were placed on the wetland side relative to the 'true ' boundary.