Segmentation of individual tree crowns in colour aerial photographs using region growing supported by fuzzy rules

Abstract

A method based on region growing for segmentation of tree crowns in aerial photographs is presented. By using a decision function, for including a pixel or not, in the spatial domain and in the colour domain simultaneously, the irregular contour of the tree crowns is kept in the segmentation result. Thus, contour information may be subsequently used for tree species classification. A set of possible candidate regions for each tree is evaluated, and the best region, according to a measure, is selected. The method is evaluated on a large sample of high spatial resolution aerial images in central Sweden. Almost 15 ha of natural regenerated boreal forests are included in the image material. On average, the identification of 73% of the tree crowns is in agreement with the corresponding results from the manual delineations. The estimation of the total number of stems from the 30 test images is 93% of the value obtained from the manual count.