{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T00:34:49Z","timestamp":1773707689712,"version":"3.50.1"},"reference-count":40,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2012,3,20]],"date-time":"2012-03-20T00:00:00Z","timestamp":1332201600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The delineation of forested areas is a critical task, because the resulting maps are a fundamental input for a broad field of applications and users. Different national and international forest definitions are available for manual or automatic delineation, but unfortunately most definitions lack precise geometrical descriptions for the different criteria. A mandatory criterion in forest definitions is the criterion of crown coverage (CC), which defines the proportion of the forest floor covered by the vertical projection of the tree crowns. For loosely stocked areas, this criterion is especially critical, because the size and shape of the reference area for calculating CC is not clearly defined in most definitions. Thus current forest delineations differ and tend to be non-comparable because of different settings for checking the criterion of CC in the delineation process. This paper evaluates a new approach for the automatic delineation of forested areas, based on airborne laser scanning (ALS) data with a clearly defined method for calculating CC. The new approach, the \u2018tree triples\u2019 method, is based on defining CC as a relation between the sum of the crown areas of three neighboring trees and the area of their convex hull. The approach is applied and analyzed for two study areas in Tyrol, Austria. The selected areas show a loosely stocked forest at the upper timberline and a fragmented forest on the hillside. The fully automatic method presented for delineating forested areas from ALS data shows promising results with an overall accuracy of 96%, and provides a beneficial tool for operational applications.<\/jats:p>","DOI":"10.3390\/rs4030762","type":"journal-article","created":{"date-parts":[[2012,3,20]],"date-time":"2012-03-20T12:07:51Z","timestamp":1332245271000},"page":"762-783","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":54,"title":["Forest Delineation Based on Airborne LIDAR Data"],"prefix":"10.3390","volume":"4","author":[{"given":"Lothar","family":"Eysn","sequence":"first","affiliation":[{"name":"Institute of Photogrammetry & Remote Sensing, Vienna University of Technology, Gu\u00dfhausstra\u00dfe 27-29, A-1040 Vienna, Austria"}]},{"given":"Markus","family":"Hollaus","sequence":"additional","affiliation":[{"name":"Institute of Photogrammetry & Remote Sensing, Vienna University of Technology, Gu\u00dfhausstra\u00dfe 27-29, A-1040 Vienna, Austria"}]},{"given":"Klemens","family":"Schadauer","sequence":"additional","affiliation":[{"name":"Department of Forest Inventory at the Federal Research and Training Center for Forests, Natural Hazards and Landscape, Seckendorff-Gudent-Weg, A-1130 Vienna, Austria"}]},{"given":"Norbert","family":"Pfeifer","sequence":"additional","affiliation":[{"name":"Institute of Photogrammetry & Remote Sensing, Vienna University of Technology, Gu\u00dfhausstra\u00dfe 27-29, A-1040 Vienna, Austria"}]}],"member":"1968","published-online":{"date-parts":[[2012,3,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1016\/S0034-4257(01)00228-0","article-title":"Estimating tree heights and number of stems in young forest stands using airborne laser scanner data","volume":"78","author":"Bjerknes","year":"2001","journal-title":"Remote Sens. 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