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Holz als Roh- und Werkstoff

, Volume 56, Issue 3, pp 193–200 | Cite as

A preliminary study on unbiased volume estimation of resin pockets using stereology to interpret CT-scanned images from one spruce log

  • E. Temnerud
  • J. Oja
Original

Abstract

Stereological methods for the volume estimation of resin pockets in saw logs were studied using computed tomography (CT) and image analysis. The Cavalieri theorem was applied for transverse sections and the Pappus theorem was applied for longitudinal radial sections. Stereology applied on wood has to consider both the linear orientation of tracheids and rays, and the circular, lamellar oriented structure of annual rings. The precision of the estimates is illustrated with varying step length between sections, i.e. varying sample size and sampling intensity. To estimate the volume of resin pockets in one log with a coefficient of error of less than 10% requires a step length of 80 mm between transverse sections or ten radial longitudinal sections 18 degrees apart. Here, the resolution of 1.37 x 1.37 x 5 mm overestimated the true volume of resin pockets. Large resin pockets can be detected, whereas detection of small resin pockets, which involved differentiation between resin pockets and compression wood, was difficult with the CT-scanner. This study proves that implementation of stereology on wood can be a good tool for quantitative analysis of resin pockets, which also means that the methods are suited for effective quality control of resin pockets in sawn timber

Keywords

Timber Step Length Annual Ring Compression Wood Radial Section 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Vorläufige Studie zum Erfassen des wirklichen Volumens von Harztaschen mit Hilfe sterologischer Auswertung der CT-Bilder yon Fichtenrundholz

Zusammenfassung

Stereologische Methoden zum Erfassen des Volumens von Harztaschen wurden an CT-Bildern mit Hilfe yon Bildanalysetechniken untersucht. Für Querschnitte wurde das Cavalieri-Theorem, für Längsschnitte das Pappus-Theorem angewendet. Die Stereologie yon Holz muff sowohl die lineare Orientierung der Tracheiden und Holzstrahlen als auch die ringförmige Lamellenstruktur der Jahrringe berticksichtigen. Die Genauigkeit der Schätzung wird anhand verschiedener Schrittweiten der Scans belegt, d.h. durch unterschiedliche Probengröße und Scandichte. Zur Schätzung des Volumens einer Harztasche in einem Rundholz mit einer Fehlerrate unter 10% erfordert eine Schrittlänge yon 80 mm zwischen den Querschnitten oder 10 radiale Längsschnitte in Schritten von je 18°. In dieser Studie war bereits eine Aufl6sung von 1,37 x 5 mm mehr als ausreichend. Große Harztaschen sind gut erkennbar, während kleine Harztaschen, die eine Differenzierung von etwaigem Druckholz erfordern, schwierig mit CT-Scannern zu erfassen sind. Die Arbeit zeigt, daß stereologische Methoden gut zur quantitativen Bildanalyse eingesetzt werden können,, d.h. daß sie sich auch für eine effektive Kontrolle yon Schnittholz (im Hinblick auf Harztaschen) eignen.

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Copyright information

© Springer-Verlag 1998

Authors and Affiliations

  • E. Temnerud
    • 1
  • J. Oja
    • 2
  1. 1.Department of Forest ProductsSwedish University of Agricultural SciencesUppsalaSweden
  2. 2.Department of Wood TechnologyLuleå University of TechnologySkelleftéaSweden

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