- Original Article
- Published:
Predicting spiral grain by computed tomography of Norway spruce
Journal of Wood Science volume 48, pages 479–483 (2002)
Abstract
Spiral grain is a feature of wood that affects the shape of the sawn timber. Boards sawn from logs with a large spiral grain have a tendency to twist when the moisture content changes. The aim of this study was to investigate the possibility of predicting spiral grain based on variables that should be measurable with an X-ray LogScanner. The study was based on 49 Norway spruce (Picea abies) logs from three stands in Sweden. The logs were scanned with a computed tomography (CT) scanner every 10mm along the log. Concentric surfaces at various distances from the pith were then reconstructed from the stack of CT images. The spiral grain angle was measured in these concentric surface images, and a statistical model for predicting spiral grain was calibrated using partial least squares (PLS) regression. The PLS model predicts the spiral grain of a log at a distance 50mm from the pith based on different variables that should be measurable with an industrial X-ray LogScanner. The result was a PLS model withR 2=0.52 for the training set andR 2=0.37 for the test set. We concluded that it should be possible to predict the spiral grain of a log based on variables measured by an industrial X-ray LogScanner. The most important variables for predicting spiral grain were measures of sapwood content, variation in the ratio between the heartwood and log areas, and the standard deviation for the mean log density in 10mm thick cross slices along the log. The accuracy when sorting the logs into two groups with spiral grain of ≥2.0° and of <2.0°, respectively, was 84% of the correctly sorted logs.
References
Harris JM (1969) Spiral grain and wave phenomena in wood formation. Springer, Berlin Heidelberg New York. ISBN 0-387-19382-0, pp 214
Skatter S, Kucera B (1997) Spiral grain: an adaptation of trees to withstand stem breakage caused by wind induced torsion. Holz Roh Werkstoff 55:207–213
Skatter S, Kucera B (1998) The cause of the prevalenl directions of the spiral grain patterns in conifers. Trees 12:265–273
Forsberg D (1999) Warp, in particular Iwist, of sawn wood of Norway spruce (Picea abies). Doctoral thesis, Swedish University of Agricultural Sciences, Uppsala. Silvestria 119; ISBN 91-576-5853-6
Sepúlveda P (2001) Measurement of spiral grain with computed tomography. J Wood Sci 47:289–293
Sepúlveda S, Grönlund A (2000) Measurement of spiral grain with computed tomography compared wilh pallern on boards: Luleå University of Technology, Skellefteå Campus, Sweden. In: Proceedings of the Conference on Wood NDT 2000, Sopron, Hungary, pp 281
Grundberg S, Grönlund A (1997) Simulated grading of logs with an X-ray LogScanner: grading accuracy compared with manual grading. Scand J For Res 12:70–76
Oja J, Grundberg S, Grönlund A (2001) Predicting the stiffness of sawn producls by X-ray scanning of Norway spruce saw logs. Scand J For Res 16:88–96
National Institutes of Health (1996) NIH Image Version 1. 61
Grundberg S, Grönlund A (1992) Log scanning: exlraclion of knot geometry. Seminar/workshop on scanning technology and image processing on wood, 1992, Skellefteå, Sweden
Lindgren O (1991) Medical CT scanner for non-destructive wood density and moisture conlenl measuremenls. Wood Sci Technol 25:341–349
Anonymous (1998) User's guide to SIMCA, version 7.0 Umetri AB, Umeå, p 230
Wold H (1982) Soft modeling: the basic design and some extensions. In: Jöreskog K-G, Wold H (eds) Systems under indirect observation, vol 2. North Holland, Amsterdam, p 343
Wold S, Ruhe A, Wold H, Dunn WJ (1984) The collinearily problem in linear regression: the partial least squares approach to generalized inverses. SIAM J Sci Comput 5:735–743
Bradley E, Gail G (1983) A leisurely look at the boolstrap, the jackknife, and cross-validation. Am Statistician 37(1):48
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sepúlveda, P., Oja, J. & Grönlund, A. Predicting spiral grain by computed tomography of Norway spruce. J Wood Sci 48, 479–483 (2002). https://doi.org/10.1007/BF00766643
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF00766643