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Automatic analysis of log end face images in the sawmill industry

Norell, Kristin (2010). Automatic analysis of log end face images in the sawmill industry. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2010:25
ISBN 978-91-576-7502-6
[Doctoral thesis]

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At present grading of sawlogs in a sawmill relies on visual inspection wherein a human expert grades a log every few seconds as it passes on a conveyor belt. This tedious and difficult work is prone to substantial inter- and intra-grader variability. This dissertation presents methods for automatic analysis of end faces from Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst). Two features are extracted: the pith (centre core) position and the number of annual rings. The pith detection uses local orientations to estimate the centre of the annual rings in a manner that is robust to disturbances as knots and cracks as well as partial coverage of dirt or snow. The number of annual rings is counted using the polar distance transform, a tool developed here. This transform combines the image intensity and the circular shape of the rings so that the annual ring pattern can be outlined in rough and noisy images. First the marks on end faces from uneven sawing are removed using an automatic method developed in this work. The data are images of untreated end faces mostly acquired at sawmills. A large amount of the data was imaged using a camera mounted above a conveyor belt at a sawmill, collecting images everymonth during one year. In total, the data consists of over 4000 images of pine and spruce. In this dissertation an algorithmfor generating synthetic log end face images is also presented. The synthetic data can be used as a tool for developing image analysis methods. The annual ring measurements were thoroughly evaluated on pine end face images acquired using the mounted end face camera. This evaluation shows that the method performs equally well as an experienced manual grader for grading the logs into quality classes. The method can thus be used as a component of an automatic grading system, overseen by a manual grader.

Authors/Creators:Norell, Kristin
Title:Automatic analysis of log end face images in the sawmill industry
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2010
Number of Pages:119
ALLKristin Norell, Creating synthetic log end face images, In proceedings of the 6th International Symposium on Image and Signal Processing and Analysis, Salzburg, Austria, pp. 353- 358, IEEE, 2009 Kristin Norell, Joakim Lindblad, and Stina Svensson, Grey weighted polar distance transformfor outlining circular and approximately circular objects, In proceedings of the 14th International Conference on Image Analysis and Processing, Modena, Italy, pp. 647-652, IEEE, 2007 Robin Strand and Kristin Norell, The polar distance transform by fast-marching, In proceedings of the 19th International Conference on Pattern Recognition, Tampa, FL, IEEE, 2008 Kristin Norell and Joakim Lindblad, Spatially-variant morphological operations on binary images based on the polar distance transform, In proceedings of the 19th International Conference on Pattern Recognition, Tampa, FL, IEEE, 2008 Kristin Norell and Gunilla Borgefors, Estimation of pith position in untreated log ends in sawmill environments, Computers and Electronics in Agriculture, 63(2):155–167, 2008. Kristin Norell, An automatic method for counting annual rings in noisy sawmill images, In proceedings of the 15th International Conference on Image Analysis and Processing, Salerno, Italy, pp. 307-316, Lecture Notes in Computer Science 5716, Springer Verlag, 2009 Kristin Norell, Counting annual rings on Pinus sylvestris end faces in sawmill industry, Submitted for journal publication
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7502-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:image analysis, growth rings, picea abies, pinus sylvestris, sawmills, automation
Keywords:image analysis, polar distance transform, coniferous end faces, wood quality, pith detection, annual ring measurements, synthetic wood images
Permanent URL:
ID Code:2274
Department:(S) > Centre for Image Analysis
Deposited By: Kristin Norell
Deposited On:22 Apr 2010 00:00
Metadata Last Modified:02 Dec 2014 10:17

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