Canadian Forest Service Publications

Forest regeneration: individual tree crown detection techniques for density and stocking assessments. 1999. Gougeon, F.A.; Leckie, D.G. Pages 169-177 in D.A. Hill and D.G. Leckie, Editors. International forum: automated interpretation of high spatial resolution digital imagery for forestry, Proceedings: Symposium. February 10-12, 1998, Victoria, British Columbia. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC.

Year: 1999

Issued by: Pacific Forestry Centre

Catalog ID: 5180

Language: English

Availability: PDF (download)

Mark record


Sustainable forest management depends on successful forest regeneration. The use of remotely sensed aerial images or digitized aerial photographs of high spatial resolution could lead to accurate and timely semi-automatic computerized assessments. Techniques based on individual tree crown detection or delineation can produce information about regenerating areas such as stem density, proper tree spacing and stocking, and even possibly, tree species and health estimations. Various computerized tree crown detection and delineation techniques already exist. Some are geared towards dense stands, while others are aimed at open areas. An hybrid detection technique is able to detect the situation at hand and switch paradigm accordingly. Delineation techniques require higher spatial resolution and/or tree sizes, but offer more promises for tree species recognition and health estimation. Most techniques can benefit from particular acquisition conditions (e.g., autumn acquisition) and simple pre-processing techniques to increase their detection or delineation capability and accuracy. This article describes two techniques presently under investigation by the authors: one of crown detection only, and another capable of crown delineation. Their strengths and weaknesses are illustrated and discussed, as are their pre-processing needs and image acquisition criteria. Various pre-processing techniques are explored. Preliminary results with aerial images of regeneration stands of various ages and densities demonstrate more quantitatively these strengths and weaknesses relative to measurements made on the ground and from aerial photographs.