Positional accuracy of boundaries between clearcuts and mature forest stands delineated by means of aerial photointerpretation

Four skilled interpreters delineated 48 boundaries between mature forest stands and clear-felled or nonproductive areas using black and white and color infrared aerial photographs. The positions of the boundaries were compared with ground-truth points located along the boundaries. On average, the interpreters located the boundaries 1.22-2.44 m inside the mature forest stands. Film type, focal length, location of the boundaries within different parts of the stereo models, and the height of the trees along the boundaries did not affect the interpretations significantly. Shadows caused by the trees, which is a hinderance to ground visibility, seriously affected the interpretation. The interpreters placed the boundaries 0.62 m farther inside the mature stands for boundaries covered by shadow than for boundaries without shadows.