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Automatic sorting of sawlogs by grade

Jäppinen, Armas (2000). Automatic sorting of sawlogs by grade. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230 ; 139
ISBN 91-576-5873-0
[Doctoral thesis]

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Optical log scanners provide a possibility for sawmills to pre-sort logs automatically by grade. Logs were classified by different grades and sawn timber properties using external log geometry variables such as taper, surface unevenness, sweep and out-of-roundness. Raw data from commercial shadow scanners and laser point 3D-scanners were used. The analyses were based on data from three sawing studies on Norway spruce, a total of 1095 logs from 22 different stands, and one sawing study on Scots pine. Logistic regression was used as the classification method, and model accuracy was assessed using the areas under receiver operating characteristic (ROC) curves. Models for sorting criteria based on knot size, knot type and grain distortion, like visual stress grades, showed a better predicting performance than commodity grade and MSR (stiffness) models. The results generally improved when variables generated from 3D-scanner data were used. Similar external geometry variables proved useful in the different studies, even if the parameter estimates differed between stands and regions. A recommendation is that mills should verify and develop classification models for their own log supply and sorting criteria. The opportunity for sawmills to use the methods to improve revenue was shown in a glulam case study, where for example high stress grades were requested. The sorting accuracy, and revenue, increased when non-geometry variables such as density and grain angle were adde

Authors/Creators:Jäppinen, Armas
Title:Automatic sorting of sawlogs by grade
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Silvestria
Year of publishing :January 2000
Number of Pages:41
ALLI. Jäppinen, A., and Nylinder, M. 1997. Automatic sorting of spruce (Picea abies (L.) Karst.) sawlogs by grade. Holz als Roh- und Werkstoff 55:301- 305. II. Jäppinen, A., and Beauregard, R. 2000. Comparing grade classification criteria for automatic sorting of Norway spruce saw logs, Scandinavian Journal of Forestry Research 14. (in press). III. Lundgren, C. and Jäppinen, A, 1998, Grading of logs using external geometry features from 3D- and profile log scanners- a comparison. Proceedings- 3rd IWSS and IUFROS 5.04-10, Skellefteå. IV. Jäppinen, A., Grade sorting of Norway spruce logs by external geometry data from a 3D-scanner. (Submitted to Forest Products Journal.) V. Jäppinen, A., Pre-sorting Norway spruce saw logs for glued-laminated timber. (Submitted to Holz als Roh- und Werkstoff
Place of Publication:Uppsala
ISBN for printed version:91-576-5873-0
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:K Forestry > K50 Processing of forest products
Subjects:Not in use, please see Agris categories
Agrovoc terms:picea abies sawlogs grading sorting equipment computer applications wood properties wood defects
Keywords:classification, geometry, grade, logistic regression, log, Picea abies, saw scanner, sorting.
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ID Code:7
Department:(S) > Institutionen för skogshushållning (fr.o.m. 990101)
Deposited By: Staff Epsilon
Deposited On:23 Apr 2002 00:00
Metadata Last Modified:02 Dec 2014 10:01

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