INVENTORY OF PLANTATION FORESTS USING CROWN DELINEATION TECHNIQUES

摘要

With the ever-increasing demands for efficiency in the forest industry comes the need for more accurate knowledge of current stock: the volume of timber in an area of forest. Recent efforts of the research community have aimed at using computer processing of aerial photographs to provide information which could contribute to these volume statistics. This paper presents results of work in progress on computer-based methods for automatically locating individual trees within New Zealand's Pinus radiata plantation forests. These methods were modifications of, and additions to, Gougeon's crown delineation heuristic. Thirty-two images of 10 plots were included in the study, with the best results obtained from images with a low sun elevation angle. Unexpectedly, smoothing of imagery before processing generally degraded the results. None of the modifications and additions trialled improved the results of the basic Gougeon method, for which the ratios of tree count estimates to ground counts had a variance of 0.035, for low sun-angle images, about a normalised mean of 1.0.