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The planning of wood procurement requires reliable information about the species-specific timber assortments on which the economic value of a production forest depends. The timber assortments refer to the stem volumes of the sawlog and pulpwood fractions, specified in terms of both timber quality and allowable log dimensions, e.g., the stem diameter at breast height (dbh). We propose here an airborne laser scanning based calibration framework for generating species-specific dbh distributions that combines the area-based approach (ABA) and individual-tree detection (ITD), two established and independent approaches for retrieving forest attributes from airborne laser scanning data. Both ABA- and ITD-derived dbh distributions were generated nonparametrically for pine, spruce, coniferous, deciduous, and all species and assessed with respect to the plot-level species-specific total stem volume ([m.sup.3] x [ha.sup.-1]) and approximations of volume of timber assortments. Although after calibration, the total volume of all species and the volume approximations of coniferous sawlog and spruce pulpwood decreased in accuracy by 4%-7%, the calibration improved the accuracy of the other 12 species-specific estimates by 2%-17%, testifying to the general effectiveness of the proposed calibration framework. Key words: species specific, forest inventory, timber assortments, diameter distribution, airborne laser scanning. La planification de l'approvisionnement en bois exige des donnees fiables au sujet des assortiments de bois specifiques a l'espece dont depend la valeur economique de la production de la foret. Les assortiments de bois referent aux fractions du volume des tiges destinees au sciage et a la pate, definies tant en termes de qualite du bois que de dimension des grumes admissible, telle que le diametre de la tige a hauteur de poitrine (dhp). Nous proposons ici une approche de calibration fondee sur le balayage laser aeroporte pour generer des distributions de dhp specifiques a l'espece qui combinent une approche par zones (APZ) et la detection d'arbres individuels (DAI), deux approches eprouvees et independantes pour obtenir des attributs forestiers a partir de donnees de balayage laser aeroporte. Les deux distributions de dhp derivees de l'APZ et de la DAI ont ete generees de facon non parametrique pour le pin, l'epicea, les coniferes, les feuillus et toutes les especes et elles ont ete evaluees quant au volume total de la tige ([m.sup.3] x [ha.sup.-1]) de chaque espece a l'echelle de la place echantillon et aux approximations du volume des assortiments de bois. Bien qu'apres calibration le volume total de toutes les especes et les approximations du volume des billes de sciage des coniferes et du bois a pate d'epicea aient diminue de 4-7 %, la calibration a ameliore la precision des douze autres estimations specifiques a l'espece de 2-17 %, temoignant de l'efficacite generale de l'approche de calibration qui est proposee. [Traduit par la Redaction] Mots-cles: specifique a l'espece, inventaire forestier, assortiment de bois, distribution des diametres, balayage laser aeroporte., 1. Introduction The planning of wood procurement counts on obtaining reliable information on stand characteristics, especially the total stem volume and the timber assortments and tree species available, which markedly [...]

Where airborne laser scanning (ALS) measures the entire aboveground vegetation, the target of a stand-level forest inventory is usually the living tree stock above a given diameter but excluding standing dead trees. The aim here was to investigate the effects of varying field-measured minimum diameters (3-10 cm) and standing dead wood on ALS-based forest inventories. The characteristics considered in this case were volume, basal area, number of stems, mean diameter, and mean height for each species, as well as the total growing stock and the total aboveground biomass. The field data comprised measurements of all trees that were ≥ 3 cm at breast height (1.3 m) on 601 sample plots located in pine-dominated managed forests in eastern Finland. The results showed that the minimum diameter had a significant effect on the estimates obtained in young forests, for which the three smallest minimum diameter datasets (3, 4, and 5 cm) gave the most accurate estimates. Minimum diameter had no marked influence in the case of middle-aged or mature forests. The inclusion of standing dead trees did not have any effect on the estimates of living tree characteristics. The effect of minimum diameter is minor where large-area inventory applications are concerned; however, especially from a silvicultural point of a view, a minimum diameter of 3 cm should be employed in young forests, for which a large proportion of the tree stock usually consists of small trees, i.e., with diameters of Key words: airborne laser scanning, k-NN, species-specific forest characteristics, diameter at breast height, field sample plot. Alors que le balayage laser aeroporte (BLA) mesure l'ensemble de la vegetation au-dessus du sol, la cible d'un inventaire forestier a l'echelle du peuplement est generalement l'ensemble des arbres vivants dont le diametre depasse un seuil donne, mais a l'exclusion des arbres morts sur pied. L'objectif de cette etude etait d'examiner les effets de differents diametres minimum mesures sur le terrain (3-10 cm) et du bois mort sur pied sur les inventaires forestiers realises au moyen du BLA. Les caracteristiques considerees dans ce cas etaient le volume, la surface terriere, le nombre de tiges, le diametre moyen et la hauteur moyenne de chaque espece ainsi que le volume total du materiel sur pied et la biomasse aerienne totale. Les donnees de terrain comprennent des mesures de tous les arbres >3 cm a hauteur de poitrine dans 601 parcelles d'echantillonnage etablies dans des forets amenagees dominees par les pins et situees dans l'est de la Finlande. Les resultats ont montre que le diametre minimum avait un effet significatif sur les estimations obtenues dans les jeunes forets, oU les ensembles de donnees composes des trois plus petits diametres minimum (3,4, et 5 cm) ont donne les estimations les plus precises. Le diametre minimum n'a pas eu d'influence marquee dans le cas des forets d'age moyen ou matures. L'inclusion des arbres morts sur pied n'a pas eu d'effet sur les estimations des caracteristiques des arbres vivants. L'effet du diametre minimum est mineur lorsque l'inventaire est applique a une grande region, mais surtout d'un point de vue sylvicole, un diametre minimum de 3 cm devrait etre utilise dans les jeunes forets, oU une grande partie du volume sur pied se compose generalement de petits arbres dont le diametre est Mots-cles: balayage laser aeroporte, k-NN, caracteristiques forestieres propres a chaque espece, diametre a hauteur de poitrine, placette d'inventaire terrain., Introduction The operational usefulness of remote sensing material was enhanced dramatically about 10-15 years ago when the airborne laser scanning (ALS) technique was developed further and became available for widespread [...]

: In this study, Lorenz curve descriptors of tree diameter inequality were used to characterize the dynamics of forest development in a shelterwood-managed Pinus sylvestris (L.) dominated area. The purpose was to stratify the forest area into forest structural types (FST) from airborne laser scanning (ALS)-based wall-to-wall predictions of the chosen indicators: Gini coefficient (GC) and Lorenz asymmetry (LA). A clear boundary at GC = 0.5 was found, which separated even-sized (below) and uneven-sized (above) areas. Furthermore, a need for including LA in the characterization of the uneven-sized areas was detected, to distinguish bimodal from reverse J-shaped stands. Beta regression was used for the ALS predictions, yielding RMSEs of 19.67% for GC and 11.01% for LA. Based on our results, we concluded that forest disturbance decreases GC, whereas seed regeneration increases GC and, therefore, gap dynamics are characterized by shifts between either side of the GC = 0.5 threshold. In even-sized stands, GC decreases toward maturity owing to self-thinning occurring at the stem exclusion stage. In uneven-sized stands, the skewness of the Lorenz curve indicates understory development, as ingrowth decreases LA. The possible applications of the resulting FST map are discussed; for instance, in identifying areas needing silvicultural treatments or evaluating forest recovery from distur-bances. Resume: Dans cette etude, des courbes de Lorenz ont ete utilisees comme descripteurs d'inegalite de la distribution diametrale des arbres pour caracteriser la dynamique du developpement d'une zone de foret dominee par Pinus sylvestris (L.) et soumise a un regime de coupe progressive. Le but etait de stratifier la superficie forestiere en types structuraux a partir de predictions en continu des indicateurs choisis sur la base d'un balayage laser aeroporte (BLA). Ces indicateurs etaient le coefficient de Gini (GC) et l'asymetrie de Lorenz (LA). Une ligne de demarcation claire de GC egale a 0,5 permettait de separer la strate reguliere (GC inferieur a 0,5) de la strate irreguliere (GC superieur a 0,5). En outre, il etait necessaire d'inclure LA dans la caracterisation de la strate irreguliere pour distinguer le peuplement a distribution diametrale bimodale du peuplement a distribution en J inverse. La regression beta a ete utilisee pour produire des modeles de prediction de GC et LA bases sur le BLA avec une erreur quadratique moyenne de 19,67 % pour GC et 11,01 % pour LA. Les resultats obtenus ont permis de conclure que: GC diminue avec la perturbation de la foret alors qu'il augmente avec la regeneration par graine et la dynamique des trouees est caracterisee par les ecarts autour d'un seuil de GC egal a 0,5. Dans les peuplements reguliers, GC diminue avec la maturite en raison de l'auto-eclaircie qui se produit au stade d'exclusion des tiges. En peuplements irreguliers, l'asymetrie de la courbe de Lorenz est un indice de developpement du sous-etage car l'augmentation des recrues fait diminuer LA. La discussion porte sur les applications possibles de la cartographie des types structuraux ainsi definis, par exemple pour identifier les peuplements necessitant des traitements sylvicoles ou pour evaluer la recuperation de la foret a la suite de perturbations. [Traduit par la Redaction], Introduction Forest dynamics and development are affected by the structural complexity of forests and the shape of their diameter distribution (Muller-Landau et al. 2006). For this reason, indicators describing forest [...]

With the development of terrestrial laser scanning (TLS) and its applications in forestry, the question arises as to how the scanners should be ideally placed for the best possible data acquisition. We searched for an optimal scanning distance for recognition of stems in natural beech-dominated forests, focusing particularly on the shading effect of tree stems and terrain. Recognised tree stems in TLS point clouds were compared with reference stem maps. A GIS-based visibility simulation was carried out to enhance the quantitative assessment and generalizability of results. The analyses also include the additive effect of multiple scanning positions. Single scans only have a tree recognition rate above 80% up to a distance of 15 m from the scanner; using at least three scanning positions a comparable recognition rate was attained up to 20-25 m. A simulated coverage of a beech-dominated natural forest by laser beams using a 40 m square grid of scanning positions captured at least half of the stem perimeter for more than 90% of trees with a DBH [greater than or equal to ]10 cm. In sites with rough terrain, the relief configuration has a more significant effect of occlusion than present tree stems. Resume: Avec le developpement du balayage laser terrestre (BLT) et de ses applications en foresterie, on s'interroge sur la position ideale des scanneurs pour recolter les meilleures donnees possibles. Nous avons cherche la distance optimale de balayage pour la reconnaissance des tiges dans une foret naturelle dominee par le hetre en mettant l'accent sur l'ombrage cause par le tronc des arbres et la topographie. La reconnaissance de la tige des arbres dans des nuages de points obtenus par BLT a ete comparee a des cartes de reference des tiges. Une simulation de la visibilite a ete effectuee a l'aide d'un SIG pour ameliorer l'evaluation quantitative et la generalisabilite des resultats. Les analyses incluaient aussi l'effet additif de positions de balayage multiples. Les balayages simples ont seulement un taux de reconnaissance de 80 % jusqu'a 15 m du scanner; un taux de reconnaissance comparable a ete obtenu jusqu'a 20-25 m en procedant au balayage a partir d'au moins trois positions. Une couverture simulee d'une foret naturelle dominee par le hetre au moyen de rayons laser, en utilisant des positions de balayage determinees par une grille carree de 40 m de cete, a capte au moins la moitie du perimetre de la tige de plus de 90 % des arbres avec un DHP [greater than or equal to ] 10 cm. Dans les stations ou le terrain est accidente, la configuration du relief a un effet d'occlusion plus important que la tige des arbres. [Traduit par la Redaction], Introduction Forest inventories are one of the main tools for decision making for forest managers, policy makers, conservation planners, and forest scientists. Traditional approaches such as area-wide stem-position mapping or [...]

As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30[degrees] x 30[degrees] in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users. [c] 2010 Optical Society of America OCIS codes: 140.0140, 280.0280, 040.0040.

The aim of this article is to review the potentiality and reliability of the integrated usage of global positioning system (GPS), terrestrial laser scanner (TLS), and total station survey measurements in the geomorphologic studies. Test surveys based on these techniques were done in the area of 'Tana della Volpe' blind valley and in the adjacent 'Monticino' quarry, near Brisighella, Ravenna, Northern Apennines, Italy. Such sites are characterized by peculiar geomorphologic attributes such as the presence of slope, karst, and anthropic forms. We surveyed about 18,000 GPS points and about 42,200,000 TLS points in a total of 22 scans. The processing of the survey's whole data set produced three distinct arrays of three-dimensional (3D) coordinates complemented by orthometric heights. Moreover, an integrated multistep procedure was implemented based on the following premises: (1) the removal of points not referred to the bare earth surface; (2) the combination of three coordinate sets into a single one referred to the whole study; (3) the generation of a bare earth digital model; and (4) the elaboration of a unified contour map. The resulting high correspondence between the observed forms and the 3D models was used to realize a detailed thematic geomorphologic map by means of which it is now possible to locate and highlight the forms observed in the field. In particular by means of TLS measurements we found a maximum difference in the spatial attitude of the observed discontinuities of 5.6[degrees] and some interesting coincidences in the evaluation of the joint roughness of several centimeters. DOI: 10.1061/(ASCE)SU.1943-5428.0000022 CE Database subject headings: Global positioning; Digital techniques; Surveys; Morphology; Case studies; Italy. Author keywords: GPS; TLS; DEM; Digital 3D modeling; Geomorphological survey.

Fault scarps represent the most obvious expression of tectonic activity at the Earth's surface. Studies on scarp morphology place constraints on fault kinematics and scarp-degradation processes, and were often based on geomorphic dating techniques. Fault scarps exposed in areas of simple topography facilitate data acquisition and interpretation, whereas little work bad been done where fault scarps are superimposed on complex, dissected topography. Fault scarps developed in complex topography are commonly observed along flower structures and at tips of strike-slip faults. Such structures are important elements for evaluating the evolution and linking of strike-slip fault systems, and appear to be scale-independent from several meters to hundreds of kilometers. We examined the detailed meter- to hundred meter--scale structure and surface expression of a flank of one fault scarp--bounded pressure ridge (Rex Hills flower structure) by combining field mapping with high-resolution digital elevation model (DEM) analysis. Based on terrestrial laser scanning we generated a detailed DEM and extracted high-resolution topographic cross sections, which enabled us to identify fault scarps and to determine their relative ages and geometry. Our study site is located on the transpressional left-bend between the Pahrump and Amargosa segments of the dextral Stateline fault system. The topography is characterized by alternating valleys and ridges (each ~100 m long, relief of ~4 m). We observed the following: the southern Rex Hills slope exhibits three fault scarps related to three reverse fault branches; the basal scarp (scarp 1) is most continuous, and exhibits five segments, the upper two scarps (scarps 2 and 3) are less continuous. Furthermore, fault scarps exposed on ridge crests are more numerous (up to four to five scarps), and smaller (~5 m high); valleys often exhibit single large (>10 m high), smoothed scarps. To easily detect differences between the scarps, we evaluated the height and slope angle of the scarps using topographic cross sections. Our analysis indicates that scarp shape is influenced by fault dip, lithology, and degradation processes resulting in large scatter and broad overlap in scarp-height--slope-angle space. The analysis further indicates that scarp degradation is stronger in the valleys, and that the preservation potential of small, individual fault scarps is therefore greater on the ridge crests. We compared our fault-scarp data with published, calibrated data yielding an age of-2 ka for the Rex Hills scarps consistent with an earlier finding. This suggests that the scarp shape mainly reflects progressive degradation since the most recent surface rupture. Our approach of analyzing high-resolution topographic data of closely spaced fault scarps is promising especially when combined with subsurface data as well as geochronological and paleoseismic data, and it provides a basic scheme for analyzing scarp populations in a complex topographic region. Despite the absence of subsurface data, our approach allowed the study of complex high-resolution fault-scarp morphologies across a flower structure for the first time. doi: 10.1130/B26536.1

Cartilage morphology change is an important biomarker for the progression of osteoarthritis. The purpose of this study was to assess the accuracy of in vivo cartilage thickness measurements from MR image-based 3D cartilage models using a laser scanning method and to test if the accuracy changes with cartilage thickness. Three-dimensional tibial cartilage models were created from MR images (in-plane resolution of 0.55 mm and thickness of 1.5 mm) of osteoarthritic knees often patients prior to total knee replacement surgery using a semi-automated B-spline segmentation algorithm. Following surgery, the resected tibial plateaus were laser scanned and made into 3D models. The MR image and laser-scan based models were registered to each other using a shape matching technique. The thicknesses were compared point wise for the overall surface. The linear mixed-effects model was used for statistical test. On average, taking account of individual variations, the thickness measurements in MRI were overestimated in thinner ( Keywords: cartilage, thickness, accuracy, osteoarthritis, MRI