Delineamento de copas de árvores em fotografias aéreas de alta resolu??o, através de suas sombras periféricas: estudo de caso na floresta ombrófila mista

摘要

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.