Log End Research Articles

Log end face image and stem tapering indicate maximum bow height on Norway spruce bottom logs

In cut-to-length logging, the harvester operator adjusts the bucking in accordance with visible defects on processed stems. Some of the defects, such as a sweep on the bottom of the stem, decrease the yield and quality of sawn products and are difficult for the operator to notice. Detecting the defects with improved sensors would support the operator in his qualitative decision-making and increase value recovery of logging. Predicting the maximum bow height of the bottom log in Norway spruce (Picea abies (L.) Karst.) with log end face image and stem taper was investigated with two modelling approaches. A total of 101 stems were selected from five clear-cut stands in southern Finland. The stems were crosscut and taper measured, and the butt ends of the bottom logs were photographed. The stem diameter, out-of-roundness, and pith eccentricity were measured from the images while the max. bow height was measured by a 3D log scanner at a sawmill. The bottom logs with an eccentric pith had higher max. bow height. In addition, a highly conical bottom part of the stem was more common on the bottom logs with a large max. bow height. Applying both log end face image and stem taper measurements gave the best model fit and detection accuracy (76%) for bottom logs with a large max. bow height. The results indicate that the log end face image and stem taper measurements can be utilised to aid harvester operator in deciding an optimised length for logs according to the bow height.

Electrical impedance and image analysis methods in detecting and measuring Scots pine heartwood from a log end during tree harvesting

Scots pine (Pinus sylvestris L.) heartwood is naturally durable wood material which has not been fully utilized in the wood industry. Currently, there are no practical measurement methods for detecting and measuring heartwood in a tree harvesting. The objective of this study was to evaluate the applicability of an electrical impedance spectroscopy and an image analysis of a log end face for pine heartwood measurements from the harvesting perspective. Both methods were tested with a fresh wood material which was collected during the harvesting operations. The results indicate that both methods have potential to measure the heartwood from processed stems with an average heartwood diameter error being less than two centimeters for each method. However, the image analysis of the log end face is only appropriate when visible contrast between the heartwood and a sapwood exists. Our findings indicate that the studied heartwood detection methods show great potential in measuring the heartwood of the stem in the harvesting phase which would ideally benefit later links in wood value chains.

Matching Score Models for Hyperspectral Range Analysis to Improve Wood Log Traceability by Fingerprint Methods

Traceability of natural resources, from the cradle to the final product is a crucial issue to secure sustainable material usage as well as to optimize and control processes over the whole supply chain. In the forest products industries the material can be tracked by different technologies, but for the first step of material flow, from the forest to the industry, no systematic and complete technology has been developed. On the way to close this data gap the fingerprint technology for wooden logs looks promising. It uses inherent properties of a wood stem for identification. In this paper hyperspectral cameras are applied to gain images of Norway spruce (Picea abies [L.] Karst.) log end faces in different spectral ranges. The images are converted to a biometric template of feature vectors and a matching algorithm is used to evaluate if the biometric templates are similar or not. Based on this, matching scores specific spectral ranges which contain information to distinguish between different log end faces are identified. The method developed in this paper is a necessary and successful step to define scanning system parameters for fingerprint recognition systems for wood log traceability from the forest.

Effect of growth stress and interlocked grain on splitting of seven different hybrid clones ofEucalyptus grandis×Eucalyptus urophyllawood

AbstractTrees with high levels of growth stress begin to show log end splits (LES) immediately after harvesting, usually reaching its maximum end split in a week, and these tensions also create splits during lumber manufacturing. Interlocked grain is another characteristic that impacts the properties of eucalyptus wood. The aim of this study was to evaluate the effect of growth stress and interlocked grain patterns on log end splitting of seven different hybrid clones ofEucalyptus grandis × Eucalyptus urophyllaplanted in Brazil. The growth stress indicator (GSI) was measured in standing trees before harvesting. Splits were measured on logs in three different stages, and interlocked grain from wood blocks was obtained across the center of the cross-section. The results showed that LES occurred as soon as the trees were harvested; however, for better selection of clones, LES should be evaluated after a week of harvesting. There were statistically significant correlations for GSI with LES. Clones that presented higher values of interlocked grain tended to develop lower values of GSI and LES. Using GSI and interlocked grain measurements, it was possible to select the most indicated eucalyptus clones for lumber production.

Possibilities of image analysis for quality wood sorting

Abstract Wood assessment optimization should be the top priority of the forestry subjects that are fundamentally dependent on the income from its sale. The aim of this paper is to analyse the beech, oak and ash tree logs that were categorized into quality classes according to the size of one of the qualitative characters related to the surface area (false heartwood, rot). The classical methodology used in forestry was compared with the application of ImageJ software. In total, thirty logs were analysed. The characters of false heartwood and rot were chosen and evaluated according to their size on the log end. There were no other characters that obstructed the categorization into quality classes. The ImageJ software application led to improved assessment (transfer to a higher quality class) in 56% of the logs. The volume of the evaluated assortments was 18.43 m3. The total difference in the value of the assortments with the ImageJ software application reached + €70.44 (+ 4.7%). The analysis therefore confirmed that in case of a considerable irregularity in a qualitative character (when the surface area of the character significantly differs from the circumscribed circular surface), the standard STN EN 1309–3 methodology systematically overvalues the surface area of this character. That affects the assessment potential of the specific log.

Magnetic Resonance Studies of Wood Log-Drying Processes

Abstract Spatially resolved measurements of moisture content (MC) in black spruce (Picea mariana Mill.) logs were undertaken by unilateral magnetic resonance (UMR) and magnetic resonance imaging (MRI). The goal of this study was to understand drying behaviors of the different regions in black spruce wood logs. Results indicate that water is lost from the entire length of the log as drying progresses. Diffusive drying from both sapwood and heartwood was observed at the log ends. The most significant drying in the log interior was through the bark. The magnetic resonance signal has an amplitude that depends on water content and a lifetime that depends on the water environment, namely, cell wall or cell lumen. The UMR measurement distinguished signal from cell wall and lumen water. The MRI measurement spatially resolved, in 3D, total water content in the wood. This was important in order to differentiate the water content and drying behavior in sapwood and heartwood. The MC in the black spruce sapwood was significantly higher than the MC in the heartwood. The water content in the cell wall does not change significantly until lumen water is depleted.

On rotational pre-alignment for tree log identification using methods inspired by fingerprint and iris recognition

Tree log end biometrics is an approach to track logs from forest to further processing companies by means of log end images. The aim of this work is to investigate how to deal with the unrestricted rotational range of cross sections in log end images. Thus, the applicability of three different rotational pre-alignment strategies in the registration procedure is assessed. Template computation and matching is based on fingerprint and iris recognition techniques which were adopted and extended to work with log end images. To address these questions, a testset built up on 279 tree logs is utilized in the experiments. The evaluation assesses the basic performance of the rotational pre-alignment strategies and their impact on the verification and identification performances for different fingerprint- and iris-based configurations. Results indicate that rotational pre-alignment in the registration procedure is the main component to deal with rotation in log end biometrics. The best configurations achieve identification rates $${>}93\,\%$$>93%. By showing that cross sections in log end images can be rotated to a distinctive position, this work is a first step towards real word log end biometrics.

Validation of models predicting modulus of elasticity in Douglas-fir trees, boles, and logs

Acoustic tools have simplified estimation of wood modulus of elasticity (MOE). Strong relationships between acoustic velocity and MOE of logs have encouraged use of acoustics at earlier points in the value chain, culminating in the development of acoustic harvesting systems. With accurate estimates of MOE of individual trees, improvements in efficiency along the value chain and increased value recovery will result. Our aim was to quantify the accuracy of MOE estimates at three distinct points: pre-harvest (standing trees), during harvest (merchantable boles), and post-harvest (5-m logs). We hypothesised that: (1) MOE estimated from acoustic velocity and wood density would provide greatest accuracy; and (2) bole estimates with a resonance tool would be more accurate than tree estimates with a time-of-flight tool. A sample of 168 Douglas-fir (Pseudotsuga menziesii [Mirb. Franco]) trees, representing the variability in acoustic velocity of 700 standing 36–51-year-old trees, was harvested from three sites. Prior to harvest, time-of-flight and breast-height diameter were recorded. After felling, resonance velocities of boles and subsequent 5-m logs were recorded. Discs, cut from log ends, were immersed, and green wood density determined. Half the logs were processed into boards, the other half into veneer sheets, and all products (in excess of 6000) non-destructively tested for MOE. MOE of parent trees, boles, and logs was then calculated from the mean MOE of derived products. Predictive mixed-effects models of tree, bole, and log MOE were developed using data from 139 trees. Fixed effects comprised combinations of velocity squared, wood density, acoustic MOE (derived from the wave equation), diameter, height, taper, and age. Random effects comprised site, plot, and, at the log level, tree. The models were validated using data from the remaining trees and compared using multiple performance metrics. For estimating tree MOE, a model with velocity squared, wood density, and taper as predictors is recommended. For estimating MOE of boles and logs, models with velocity squared and wood density are recommended. The models have an accuracy, as determined by RMSE, of about ± 2 GPa. For accurate MOE estimation, velocity alone is insufficient. Knowledge of wood density is necessary for improved accuracy.

Tracking Logs with RGB Images within the Wood Supply Chain: A Preliminary Study on Image Acquisition

Abstract In addition to the fact that actions have been taken by the European Union and the World Bank to impede illegal logging worldwide, full traceability of logs would also be of benefit to the timber industry and market participants. Therefore, in this study, basic conditions for RGB image acquisition are derived for tracking roundwood by means of biometric features on log end faces within the wood supply chain from stump to sawmill. For this purpose, 24 logs were initially photographed in the forest after felling and photographed a second time 8 weeks later in the sawmill. Difficulties in image acquisition were analyzed qualitatively as well as quantitatively by comparing the images made in the forest with those made in the sawmill. The quantitative evaluation was carried out using different measures that are well established with respect to digital image processing. Tracking efforts solely by means of these measures turned out to be unsuitable. However, the shape measures performed best and are assumed to be supportive in combination with other methods. Therewith, conditions for a practical implementation in the future can be deduced.

Towards the applicability of biometric wood log traceability using digital log end images

Log traceability in the timber based industries is a basic requirement to fulfil economical, social and legal requirements. This work introduces biometric log recognition using digital log end images and explores the robustness to a set of log end cross-section (CS) variations. In order to investigate longitudinal and surface CS variations three tree logs were sliced and captured in different sessions. A texture feature-based technique well known from fingerprint recognition is adopted to compute and match biometric templates of CS images captured from log ends. In the experimental evaluation insights and constraints on the general applicability and robustness of log end biometrics to identify logs in an industrial application are presented. Results for different identification performance scenarios indicate that the matching procedure which is based on annual ring pattern and shape information is very robust to log length cutting using different cutting tools. The findings of this study are a further step towards the development of a biometric log recognition system.

THE LTE SOLAR ABUNDANCE OF NEODYMIUM

We study the solar photospheric abundance of singly ionized neodymium (Nd II) using high resolution spectroscopic dataobtained by Fourier transform spectrograph (FTS). Based on the Local Thermodynamical Equilibrium (LTE) assumption,a new value of Nd abundance is derived. We succeed to select of 51 solar Nd II lines with accurate transition probabilitiesmeasured experimentally by Den Hartog et al. (2003) and with accurate damping parameters are determined from literature.Relying on atomic data of Opacity Distribution Function (ODF), we construct theoretical photospheric solar model.The meansolar photospheric abundance obtained from all 51Nd II lines is log eNd= , which is mostly similar to the meteoricvalue.

Plywood Industry by Using Eco-efficiency Approach and LIA- Wood Balance Sheet Program

The general purposes of this study were to improve the efficiency of wood utilization and to create wood’s value added for plywood industry. To achieve the above purposes a strategy for Agro forestry Industry should be develop based on eco-efficiencyprinciples. The details of targets were: (1). to analyze critical factors in plywood industry management regarding to eco-efficiency implementation, (2) to analyze production technology that is used in plywood industry, and (3). to design a developing strategy of integrated plywood industry based on eco-efficiency principles. The result of this study show that the key factors for plywood management’s policy was environmental awareness; material utilization; and international issues. The production technology of all plywood industry in Indonesia is relatively similar. They are using the machineries of the 80’s and have the similar working procedures. The kinds of wood wastes generated from plywood industry were classified into log end, reject log end, green veneer waste, and others. The wood waste was calculated 49.52% released from 100% input log in plywood industry. There are three strategy of integrated plywood industry based on eco-efficiency, namely (1) selecting and managing of environmental impact, showing three kinds of waste which affect the environment (2) Improvement the plywood manufacturing technology, showing the newinnovation technology or process control management and (3) Development of new product from wood waste. Wood waste can be used to produce block board, laminated board, handicraft, and others.

Relationship between tree morphology and growth stress in mature European beech stands

In European Beech (Fagus sylvatica L.) large growth stresses lead to severe log end splitting that devaluate beech timber. Our study aimed at detecting relationships between growth stress and some morphology parameters in trees. Growth stress indicators were recorded for 440 mature trees in nine stands from five European countries, together with morphology parameters. Most trees displayed an uneven distribution of growth stress around the trunk. Moreover, growth stress intensity varied largely between individual trees. Geometry of the trunk was a poor predictor of growth stress intensity. Crown asymmetry resulted in a larger stress dissymmetry within trees. Trunk inclination was not correlated to max tension stress, contrary to what is usually found in younger trees. In the case of small inclination, growth stress was close to expected from biomechanics of restoring verticality. Trees exhibiting a larger inclination probably evolved a different mechanical solution: a rather large crown, lower tree slenderness and a sufficient asymmetry in growth stress as to prevent a higher inclination due to growth. A large slenderness is the best accurate predictor of a large growth stress, although variations in the ratio height/diameter at breast height explained only 10 % of the variability of growth stress. A large crown surface was the best predictor of a low level of growth stress. A large spacing between trees seems a good solution to lower the risk of growth stress in mature beech.

Genetic variation in traits affecting sawn timber recovery in plantation-grown Eucalyptus nitens

& Introduction There is increasing interest in managing Eucalyptus nitens plantations for sawn timber production. & Aims This study aimed to determine the potential for genetic improvement of traits affecting green sawn board recovery in plantation-grown E. nitens. & Methods The study was undertaken on an E. nitens progeny trial. All trees were measured for diameter at breast height (DBH) and stem straightness, and 560 trees were selected for timber processing. Assessment was made of survival, log and green sawn board volume, log taper, and both upper and lower log end splitting. Genetic variation in and between these traits was estimated. & Results Geneticdifferencesamongracesweresignificantfor DBH at years 9 and 14, stem straightness, log taper and green sawn board volume. Within-race, narrow-sense heritabilities were significant for DBH, stem straightness, log volume, and both upper and lower log end splitting. Positive and significant additive genetic correlations were observed between DBH at all ages and survival, stem straightness and log volume. Significant adverse genetic correlations were shown between upper log end splitting and DBH at years 9 and 14. & Conclusion These findings showed that harvest-age stem straightness and log volume objective traits in E. nitens are amenable to genetic improvement and that selection for early-age DBH in breeding programmes should improve harvest-age survival, stem diameter and straightness, as well as log and green sawn board volume. However, these improvements are likely to be countered to some extent by increased end splitting of logs from larger trees.

Automatic counting of annual rings on Pinus sylvestris end faces in sawmill industry

Abstract The quality of wood can be analyzed using annual ring width. At Swedish sawmills, this is performed using manual inspection for grading purpose. Here a completely automatic method for counting the number of annual rings on log end faces is described and evaluated. The method is applied and tested using images from Pinus sylvestris end faces acquired in online sawmill production with a camera mounted above a conveyor belt. Completely untreated end faces were captured, as well as newly sawn ones. The proposed method includes preprocessing, pith detection and counting the number of rings in two regions of the end face. A new method to remove marks from uneven sawing is presented as a part of the preprocessing steps. The evaluation shows that the suggested automatic method performs as well as the manual measurements that are the method used for measuring today.

Determination of Basic Density and Moisture Content of Merchantable Loblolly Pine Logs by near Infrared Spectroscopy

The use of near infrared (NIR) diffuse reflectance spectroscopy for the estimation of basic density and moisture content of loblolly pine ( Pinus taeda L.) logs was explored. A total of 219 wood disks representing the large and small ends of 146 merchantable logs 4.87 m in length, ranging in age from 13 years to 19 years, were analysed. NIR spectra were obtained from the transverse surface of the disks when the wood was green using a Foss XDS NIR System coupled with a Smart Probe Analyser. Each disk was divided into four quadrants and two spectra were collected per quadrant (one representing juvenile wood and one mature wood). NIR calibration models were fitted using pre-processed spectra with multiplicative scatter correction and the dimensionality of the models was kept constant for comparison purposes. Successful models based on an average of all spectra collected from both ends of the logs were obtained for basic density ( R2c = 0.84) and moisture content ( R2c = 0.85) using nine factors for both properties. The predictive ability of the calibrations was acceptable, with mean square errors of 22.8 kg m−3 for basic density and 2.1% for moisture content. It was found that the number of spectra per disk could be reduced to four readings but further reductions increased prediction errors considerably. Calibration models based only on spectra collected from one of the log ends were also examined. Using large-end diameter spectra only, the fit statistics for basic density models fell to R2 c=0.76 for (eight spectra) and R2c=0.71 (four spectra). Similarly, the fit statistics for moisture content calibrations dropped to R2c=0.76 for (eight spectra) and R2c=0.72 (four spectra). Calibrations based only on small-end diameter spectra were considerably weaker than those based on large-end diameter spectra.

Improved Methods for Achieving Traceability of Tree and Log Identities in Timber Processing Studies

We successfully tracked the identities of more than 550 selected 13-year-old trees from a Eucalyptus nitens (Deane & Maiden) progeny trial through tree felling, harvesting of butt logs, and sawmill processing to finished sawn boards using a two-stage approach. To track log identity from the standing tree to the log yard, we used a numbered under-bark wooden identification plug, glued into a hole drilled in the trunk prior to harvesting. To track tree identity for individual sawn boards, log-end templates with corresponding tree identification numbers were glued to the log ends before milling. Materials and methods used withstood harvesting and debarking, log transportation, milling, air and kiln drying, steam reconditioning, and final machining. A second study confirmed the success of the under-bark plug method to successfully track 548 selected standing trees through harvesting and transportation to the mill.

Scheduling production for a sawmill: A comparison of a mathematical model versus a heuristic

Sawmill production scheduling is complex. It involves determining which logs to process taking into account the diameter, length, and grade of each log, on one hand, and the finished products that are needed to fulfill the orders, on the other. The cutting pattern determines which products are generated and also the yield, which is how much of the volume of the log ends as finished products. We used two approaches to solve the problem: a mathematical model, which calculates the volume and the schedule of various types of logs, and a heuristic that solves the problem by systematically applying the criteria used by a sawmill programmer in southern Chile. We compare the results of using both approaches under various scenarios in a 6 week planning horizon, with the mathematical model showing a superior performance in almost all instances except two, were both found the optimal solution. The proposed mathematical model can be solved in a relatively short time, which makes it a suitable basis of a practical optimization-based decision support system.

Directional variance analysis of annual rings

The wood quality measurement methods are of increasing importance in the wood industry. The goal is to produce more high quality products with higher marketing value than is produced today. One of the key factors for increasing the market value is to provide better measurements for increased information to support the decisions made later in the product chain. Strength and stiffness are important properties of the wood. They are related to mean annual ring width and its deviation. These indicators can be estimated from images taken from the log ends by two-dimensional power spectrum analysis. The spectrum analysis has been used successfully for images of pine. However, the annual rings in birch, for example are less distinguishable and the basic spectrum analysis method does not give reliable results. A novel method for local log end variance analysis based on Radon-transform is proposed. The directions and the positions of the annual rings can be estimated from local minimum and maximum variance estimates. Applying the spectrum analysis on the maximum local variance estimate instead of the original image produces more reliable estimate of the annual ring width. The proposed method is not limited to log end analysis only. It is usable in other two-dimensional random signal and texture analysis tasks.

Longitudinal growth strain as a log and wood quality predictor for plantation-grown Eucalyptus nitens sawlogs

Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old pruned Eucalyptus nitens trees from five thinning treatments in a plantation thinning trial in Tasmania. Growth strain data were gathered at breast height on each tree using the CIRAD-Foret method. The effects of thinning treatment and tree diameter on LGS and its relationships to solid-wood traits determined in a processing trial were examined. LGS was significantly higher in the direction of the prevailing wind and was not significantly affected by either thinning treatment or tree diameter. An index of log end splitting was positively related to tree diameter, sawlog position (upper/lower), and LGS, which explained up to an additional 20% of the variance after tree diameter and log position were accounted for in a linear regression model. High LGS and log end splitting were significant indicators of increased board end splitting.