This paper deals with the semi automatic delineation of crowns of trees on high resolution aerial photograph using their peripheral shadows. The study was carried out on 2 hectares of native Araucaria forest due to the avaliability of field data and the interpretation, in analogic and digital formats, of a 70 mm 1:1.000 high resolution aerial photograh . The methodology consisted in the transformation of the 3 original bands of the digital color photograph in only one, and then, through a threshold, the shadow component was separated from the other targets. From the results obtained, the main conclusions reached were: a) the shadows were due to the open areas on the forest among the branches and the crowns of the trees; b) the resultant image evidenced the inconsistency to delineate the crowns exclusively through their peripheral shadows; c) the inadequate result may be related to the type of natural forest and not to the technique itself; d) the used technique showed promising as an additional enhancement technique, and e) it is necessary to carry out more research in order to obtain conclusive results.
high resolution aerial photograph; illumination/albedo image; peripheral shadows; araucaria forest
