Index of efficiency for strength-grading machines for solid wood

The settings of strength-grading machine for structural pieces of wood are checked according to the EN 14081 standard. However, different machines have different performances depending on the accuracy of the estimation of the board’s properties, and there is no easy way to compare the efficiency of these machines especially if the machine does not use the same sampling. In this paper, we introduce an index called index of efficiency for grading machines. This parameter is in the range of 0–100% and allows to compare performances of different machines for a given set of grades. The computation of this index is based on the cost matrix method of the EN 14081 and requires to have the size matrix of a setting to be computed

Détection automatique de la moelle sur des images d'extrémités de grumes de Douglas brutes de sciage

National audienc

Digital Straight Segment Filter for Geometric Description

International audienceIn this paper, an algorithmic scheme is proposed to estimate different local characteristics of image structures using discrete geometry tools. The arithmetic properties of Digital Straight Lines and their link with the Farey sequences allow the introduction of a new directional filter. In an incremental process, it provides local geometric information at each point in an image, such as the length, orientation and thickness of the longest Digital Straight Segment passing through that point. Experiments on binary and grayscale images are proposed and show the interest of this tool. Comparisons to a well-known morphological filter for grayscale images are also presented

Knot Detection in X-Ray CT Images of Wood

International audienceThis paper presents an original problem of knot detection in 3D X-ray Computer Tomography images of wood stems. This image type is very different from classical medical images and presents specific geometric structures. These ones are characteristic of wood stems na- ture. The contribution of this work is to exploit the original geometric structures in a simple and fast algorithm to automatically detect and analyze the wood knots. The proposed approach is robust to different wood qualities, like moisture or noise, and more simple to implement than classical deformable models approaches

Pith Estimation on Tree Log End Images

International audienceIn this paper, we present an algorithm for pith estimation from digital images of wood cross-sections. The method is based on a probabilistic approach, namely ant colony optimization (ACO). After introducing the approach, we describe the implementation and the reproduction of the method linking to an online demonstration. Results show that the approach performs as well as state-of-the-art methods. The estimated pith is below 5mm from the ground truth. It is a fast method that could be used in real-time environment. This paper also gives the details about the intern parameter choice and shows how to use the C++ source code for testing, as well as provides limit cases of the proposed method and future improvements

Segmentation robuste de nœuds à partir de coupes tangentielles issues d'images tomographiques de bois

National audienceCet article présente une méthode rapide, précise et automatique pour segmenter les nœuds de bois à partir d'images volumiques de troncs d'arbres obtenues par scanner à rayons X. La segmentation des nœuds est un probléme récurrent où les techniques classiques produisent des résultats non satisfaisants. Un premier travail nous a permis de développer une méthode capable d'isoler chaque nœud. Quelques approches ont été proposées pour la segmentation de ces nœuds isolés mais elles ne sont pas entièrement satisfaisantes en présence de zones humides. Nous présentons ici une nouvelle approche pour répondre à ce probléme, basée sur l'idée originale de coupes tangentes aux cernes. Elles permettent de suivre la trajectoire du nœud de la moelle du tronc jusqu'à l'écorce. Les nœuds sont segmentés par détection d'ellipses discrètes dans chaque coupe tangentielle. Une implémentation complète de la méthode est proposée dans le logiciel TKDetection, disponible librement

Automatic knot detection and measurements from X-ray CT images of wood: A review and validation of an improved algorithm on softwood samples

International audienceAn algorithm to automatically detect and measure knots in CT images of softwood beams was developed. The algorithm is based on the use of 3D con- nex components and a 3D distance transform constituting a new approach for knot diameter measurements. The present work was undertaken with the objective to automatically and non-destructively extract the distributions of knot characteristics within trees. These data are valuable for further studies related to tree development and tree architecture, and could even contribute to satisfying the current demand for automatic species identification on the basis of CT images. A review of the literature about automatic knot detection in X-ray CT images is provided. Relatively few references give quantitatively accurate results of knot measurements (i.e., not only knot localisation but knot size and incli- nation as well). The method was tested on a set of seven beams of Norway spruce and silver fir. The outputs were compared with manual measurements of knots performed on the same images. The results obtained are promising, with detection rates varying from 71 to 100%, depending on the beams, and no false alarms were reported. Particular attention was paid to the accuracy obtained for automatic measurements of knot size and inclination. Comparison with manual measurements led to a mean R2 of 0.86, 0.87, 0.59 and 0.86 for inclination, maximum diameter, length and volume, respectively

Cutting Forces in basic and real life wood machining processes review, COST Action E35 2004-2008: Wood machining - Micromechanics and fracture

The data available in the literature concerning wood cutting forces permit to build models or to simulate the main wood machining processes (milling, sawing, peeling etc.). This approach contributes to a better understanding of formation of wood surfaces and chips and the data may be helpful to optimize cutting geometry, reduce tool wear, improve tool material, and to size tool-machines. The models may also be useful for industrial application in two ways: (1) providing data to optimise the settings for a given operation (batch approach) and (2) building predictive models that could be the basis of an online control systems for the machining processes (interactive approach). A prerequisite for this is that numerous machining tests on different wood materials are performed based on experiences with different kind of tools and experimental devices. With potential industrial applications in focus, the emphasis of this review was on the wood peeling process, which is a very demanding special case of wood cutting. Though not so many industrial machines are equipped with expensive force sensors, there is a lot of high quality information available about cutting forces which may be useful to improve the scientific or technologic knowledge in wood machining. Alternative parameters, such as vibration or sound measurements, appear to be promising substitutes in the praxis, particularly to feed online control systems of any wood cutting process.Cost Action E35 2004-200