• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 23
  • 9
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 55
  • 55
  • 55
  • 14
  • 12
  • 11
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 9
  • 9
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Modeling Forest Canopy Distribution from Ground-Based Laser Scanner Data

Henning, Jason Gregory 18 August 2005 (has links)
A commercially available, tripod mounted, ground-based laser scanner was used to assess forest canopies and measure individual tree parameters. The instrument is comparable to scanning airborne light detection and ranging (lidar) technology but gathers data at higher resolution over a more limited scale. The raw data consist of a series of range measurements to visible surfaces taken at known angles relative to the scanner. Data were translated into three dimensional (3D) point clouds with points corresponding to surfaces visible from the scanner vantage point. A 20 m x 40 m permanent plot located in upland deciduous forest at Coweeta, NC was assessed with 41 and 45 scans gathered during periods of leaf-on and leaf-off, respectively. Data management and summary needs were addressed, focusing on the development of registration methods to align point clouds collected from multiple vantage points and minimize the volume of the plot canopy occluded from the scanner's view. Automated algorithms were developed to extract points representing tree bole surfaces, bole centers and ground surfaces. The extracted points served as the control surfaces necessary for registration. Occlusion was minimized by combining aligned point clouds captured from multiple vantage points with 0.1% and 0.34% of the volume scanned being occluded from view under leaf-off and leaf-on conditions, respectively. The point cloud data were summarized to estimate individual tree parameters including diameter at breast height (dbh), upper stem diameters, branch heights and XY positions of trees on the plot. Estimated tree positions were, on average, within 0.4 m of tree positions measured independently on the plot. Canopy height models, digital terrain models and 3D maps of the density of canopy surfaces were created using aligned point cloud data. Finally spatially explicit models of the horizontal and vertical distribution of plant area index (PAI) and leaf area index (LAI) were generated as examples of useful data summaries that cannot be practically collected using existing methods. / Ph. D.
22

Terrestrial Laser Scanning for Quantifying Uncertainty in Fluvial Applications

Resop, Jonathan P. 20 July 2010 (has links)
Stream morphology is an important aspect of many hydrological and ecological applications such as stream restoration design (SRD) and estimating sediment loads for total maximum daily load (TMDL) development. Surveying of stream morphology traditionally involves point measurement tools, such as total stations, or remote sensing technologies, such as aerial laser scanning (ALS), which have limitations in spatial resolution. Terrestrial laser scanning (TLS) can potentially offer improvements over other surveying methods by providing greater resolution and accuracy. The first two objectives were to quantify the measurement and interpolation errors from total station surveying using TLS as a reference dataset for two fluvial applications: 1) measuring streambank retreat (SBR) for sediment load calculations; and 2) measuring topography for habitat complexity quantification. The third objective was to apply knowledge uncertainties and stochastic variability to the application of SRD. A streambank on Stroubles Creek in Blacksburg, VA was surveyed six times over two years to measure SBR. Both total station surveying and erosion pins overestimated total volumetric retreat compared to TLS by 32% and 17%, respectively. The error in SBR using traditional methods would be significant when extrapolating to reach-scale estimates of sediment load. TLS allowed for collecting topographic data over the entire streambank surface and provides small-scale measurements on the spatial variability of SBR. The topography of a reach on the Staunton River in Shenandoah National Park, VA was measured to quantify habitat complexity. Total station surveying underestimated the volume of in-stream rocks by 55% compared to TLS. An algorithm was developed for delineating in-stream rocks from the TLS dataset. Complexity metrics, such as percent in-stream rock cover and cross-sectional heterogeneity, were derived and compared between both methods. TLS quantified habitat complexity in an automated, unbiased manner at a high spatial resolution. Finally, a two-phase uncertainty analysis was performed with Monte Carlo Simulation (MCS) on a two-stage channel SRD for Stroubles Creek. Both knowledge errors (Manning's <i>n</i> and Shield's number) and natural stochasticity (bankfull discharge and grain size) were incorporated into the analysis. The uncertainty design solutions for possible channel dimensions varied over a range of one to four times the magnitude of the deterministic solution. The uncertainty inherent in SRD should be quantified and used to provide a range of design options and to quantify the level of risk in selected design outcomes. / Ph. D.
23

Integrating Laser Scanning with Discrete Element Modeling for Improving Safety in Underground Stone Mines

Monsalve, Juan J. 10 May 2019 (has links)
According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is a predominant failure mechanism in underground limestone mines. This type of instability occurs when the different discontinuity sets intercept with each other forming rock blocks that displace inwards the tunnel as the excavation takes place, posing a great hazard for miners and overall mine planning. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed numerical modeling codes to represent more realistically the behavior of a fractured rock masses. This work presents and implements a methodology that integrates laser scanning technology along with Discrete Element Modeling as tools for characterizing, preventing, and managing structurally controlled instability that may affect large-opening underground mines. The stability of an underground limestone mine that extracts a dipping ore body with a room and pillar (and eventual stoping) mining method is analyzed with this approach. While this methodology is proposed based on a specific case study that does not meet the requirements to be designed with current NIOSH published guidelines, this process proposes a general methodology that can be applied in any mine experiencing similar failure mechanisms, considering site-specific conditions. The aim of this study is to ensure the safety of mine workers and to reduce accidents that arise from ground control issues. The results obtained from this methodology allowed us to generate Probability Density Functions to estimate the probability of rock fall in the excavations. These models were also validated by comparing the numerical model results with those obtained from the laser scans. / M.S. / According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is one of the main causes of rock falls in underground limestone mines. This type of instability occurs when the fractures present in the rock mass intercept each other forming rock blocks that displace into the tunnel as the excavation takes place and poses a great hazard for miners. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed simulation softwares such as the Discrete Element Model (DEM) to represent more realistically the behavior of a fractured rock mass under excavation. The aim of this work was to develop and evaluate a methodology that could complement already exisiting design guidelines that may not apply to all kind of underground mines. The presented methodology evaluates rock failure due to presence of discontinuites, through the integration of TLS with DEM and considers site specific conditions. An area of a case study mine was assessed with this methodology, where several laser scans were performed. Information extracted from this laser scans was used to simulate the response of the rock mass under excavation by running Discrete Element Numerical Models. Results from these models allowed us to estimate the probability of rock failure in the analized areas. These, rock block failure probability estimations provide engineers a tool for characterizing, preventing, and managing structurally controlled instability, and ultimately improving workers safety.
24

The role of large woody debris on sandy beach-dune morphodynamics

Grilliot, Michael J. 30 April 2019 (has links)
Coastal foredune evolution involves complex processes and controls. Although a great deal is known about the effects of vegetation cover, moisture, and fetch distance on sediment supply, and of topographic forcing on airflow dynamics, the role of large woody debris (LWD) as a modulator of sediment supply and a control on foredune growth is understudied. Large assemblages of LWD are common on beaches near forested watersheds and collectively have a degree of porosity that increases aerodynamic roughness and provides substantial sand trapping volume. To date, no research has attempted to understand the geomorphic role that LWD matrices, as a whole, have as roughness elements affecting airflow and sediment transport across a beach-dune system, or, what the long-term implications of these impacts are on beach and foredune erosion recovery and evolution. This four-year research initiative investigated the role of a LWD matrix on beach-dune morphodynamics on West Beach, Calvert Island on the central coast of British Columbia, Canada. This study integrated data from research that spanned three temporal scales, 1) event-scale (10 min) flow and sediment transport patterns, 2) daily frequency and relative magnitude of landscape changing events, 3) seasonal to interannual-scale volumetric and LWD changes. An event-scale experiment to characterise airflow dynamics and related sand transport patterns showed that LWD distinctly alters wind flow patterns and turbulence levels from that of incoming flow over a flat beach. Overall, mean wind speed and fluctuating flow properties declined as wind transitioned across the LWD. Streamwise mean energy was converted to turbulent energy, however, the reductions in mean flow properties were too great for the increased streamwise turbulence to have an effect on transport. In response to these flow alterations and more limited sand transport pathways to the foredune, sediment flux was reduced by 99% in the LWD compared to the open beach, thereby reducing sand supply to the foredune. Sand grains rebounding off of the LWD were carried higher into the flow field resulting in greater mass flux recorded at 20-50 cm in the LWD as opposed to the flat beach. This effect was only recorded 6 m into the LWD. As such, LWD has the potential to modulate rates of foredune recovery, growth, and evolution. Time-lapse photography collected at 15 min intervals during the study revealed that storm events lead to wave-induced erosion of the backshore and reworking of the LWD matrix. The exposed LWD matrix subsequently traps aeolian sediment that leads to rapid burial of the LWD and building of a raised platform for emergent vegetation. However, infilling of the accommodation space within the LWD matrix is so rapid, that sediment starvation of the foredune is short-lived. While the LWD at this site does trap sediment in the backshore, helping to protect the dune from scarping, LWD at this study site maintains an overall lower impact on transport to the foredune. Critical to this relationship is the frequency and magnitude of nearshore events that erode the beach periodically and re-organize the LWD matrix, which directly impacts the ability of LWD to store sediment and modulate transport to the foredune. A conceptual model exploring these relationships is presented. / Graduate
25

Mapping the Spatial Movements, Behaviors, and Interactions of Captive Orangutans using Terrestrial Laser Scanning and GIS

Smith, Zachary Joseph 22 April 2014 (has links)
Five captive Bornean orangutans (Pongo pygmaeus) were observed in order to better understand their spatial selection, behavior, and interaction with their environment and each other. A newly introduced adult male's interactions with a female group containing two adults, one adolescent, and one juvenile, was documented. Visual observations were performed to document individual behaviors, along with any interactions with silvery langur monkeys, public crowd levels, temperature, and enrichment props. Methods included 15 observation periods, 0.5-3 hours in length each, during which behaviors were verbally and visually confirmed using a HD video camera. Spatial locations of each individual were recorded every three minutes during each observation period. The orangutan enclosure was measured and mapped using terrestrial laser scanning (TLS), and observed behaviors and spatial locations were georeferenced to the resulting 3D model depicting the exhibit. Results were summarized as time-activity budgets and were geo-visualized using 3D plots and density maps. This research demonstrated how the application of spatiotemporal and behavioral analysis coupled with TLS and three-dimensional modelling can be used to better study captive primates. These types of studies are important as zoos increasingly become home to great ape species.
26

Geometrische und stochastische Modelle für die integrierte Auswertung terrestrischer Laserscannerdaten und photogrammetrischer Bilddaten

Schneider, Danilo 07 September 2009 (has links) (PDF)
Terrestrische Laserscanner finden seit einigen Jahren immer stärkere Anwendung in der Praxis und ersetzen bzw. ergänzen bisherige Messverfahren, oder es werden neue Anwendungsgebiete erschlossen. Werden die Daten eines terrestrischen Laserscanners mit photogrammetrischen Bilddaten kombiniert, ergeben sich viel versprechende Möglichkeiten, weil die Eigenschaften beider Datentypen als weitestgehend komplementär angesehen werden können: Terrestrische Laserscanner erzeugen schnell und zuverlässig dreidimensionale Repräsentationen von Objektoberflächen von einem einzigen Aufnahmestandpunkt aus, während sich zweidimensionale photogrammetrische Bilddaten durch eine sehr gute visuelle Qualität mit hohem Interpretationsgehalt und hoher lateraler Genauigkeit auszeichnen. Infolgedessen existieren bereits zahlreiche Ansätze, sowohl software- als auch hardwareseitig, in denen diese Kombination realisiert wird. Allerdings haben die Bildinformationen bisher meist nur ergänzenden Charakter, beispielsweise bei der Kolorierung von Punktwolken oder der Texturierung von aus Laserscannerdaten erzeugten Oberflächenmodellen. Die konsequente Nutzung der komplementären Eigenschaften beider Sensortypen bietet jedoch ein weitaus größeres Potenzial. Aus diesem Grund wurde im Rahmen dieser Arbeit eine Berechnungsmethode – die integrierte Bündelblockausgleichung – entwickelt, bei dem die aus terrestrischen Laserscannerdaten und photogrammetrischen Bilddaten abgeleiteten Beobachtungen diskreter Objektpunkte gleichberechtigt Verwendung finden können. Diese Vorgehensweise hat mehrere Vorteile: durch die Nutzung der individuellen Eigenschaften beider Datentypen unterstützen sie sich gegenseitig bei der Bestimmung von 3D-Objektkoordinaten, wodurch eine höhere Genauigkeit erreicht werden kann. Alle am Ausgleichungsprozess beteiligten Daten werden optimal zueinander referenziert und die verwendeten Aufnahmegeräte können simultan kalibriert werden. Wegen des (sphärischen) Gesichtsfeldes der meisten terrestrischen Laserscanner von 360° in horizontaler und bis zu 180° in vertikaler Richtung bietet sich die Kombination mit Rotationszeilen-Panoramakameras oder Kameras mit Fisheye-Objektiv an, weil diese im Vergleich zu zentralperspektiven Kameras deutlich größere Winkelbereiche in einer Aufnahme abbilden können. Grundlage für die gemeinsame Auswertung terrestrischer Laserscanner- und photogrammetrischer Bilddaten ist die strenge geometrische Modellierung der Aufnahmegeräte. Deshalb wurde für terrestrische Laserscanner und verschiedene Kameratypen ein geometrisches Modell, bestehend aus einem Grundmodell und Zusatzparametern zur Kompensation von Restsystematiken, entwickelt und verifiziert. Insbesondere bei der Entwicklung des geometrischen Modells für Laserscanner wurden verschiedene in der Literatur beschriebene Ansätze berücksichtigt. Dabei wurde auch auf von Theodoliten und Tachymetern bekannte Korrekturmodelle zurückgegriffen. Besondere Bedeutung innerhalb der gemeinsamen Auswertung hat die Festlegung des stochastischen Modells. Weil verschiedene Typen von Beobachtungen mit unterschiedlichen zugrunde liegenden geometrischen Modellen und unterschiedlichen stochastischen Eigenschaften gemeinsam ausgeglichen werden, muss den Daten ein entsprechendes Gewicht zugeordnet werden. Bei ungünstiger Gewichtung der Beobachtungen können die Ausgleichungsergebnisse negativ beeinflusst werden. Deshalb wurde die integrierte Bündelblockausgleichung um das Verfahren der Varianzkomponentenschätzung erweitert, mit dem optimale Beobachtungsgewichte automatisch bestimmt werden können. Erst dadurch wird es möglich, das Potenzial der Kombination terrestrischer Laserscanner- und photogrammetrischer Bilddaten vollständig auszuschöpfen. Zur Berechnung der integrierten Bündelblockausgleichung wurde eine Software entwickelt, mit der vielfältige Varianten der algorithmischen Kombination der Datentypen realisiert werden können. Es wurden zahlreiche Laserscannerdaten, Panoramabilddaten, Fisheye-Bilddaten und zentralperspektive Bilddaten in mehreren Testumgebungen aufgenommen und unter Anwendung der entwickelten Software prozessiert. Dabei wurden verschiedene Berechnungsvarianten detailliert analysiert und damit die Vorteile und Einschränkungen der vorgestellten Methode demonstriert. Ein Anwendungsbeispiel aus dem Bereich der Geologie veranschaulicht das Potenzial des Algorithmus in der Praxis. / The use of terrestrial laser scanning has grown in popularity in recent years, and replaces and complements previous measuring methods, as well as opening new fields of application. If data from terrestrial laser scanners are combined with photogrammetric image data, this yields promising possibilities, as the properties of both types of data can be considered mainly complementary: terrestrial laser scanners produce fast and reliable three-dimensional representations of object surfaces from only one position, while two-dimensional photogrammetric image data are characterised by a high visual quality, ease of interpretation, and high lateral accuracy. Consequently there are numerous approaches existing, both hardware- and software-based, where this combination is realised. However, in most approaches, the image data are only used to add additional characteristics, such as colouring point clouds or texturing object surfaces generated from laser scanner data. A thorough exploitation of the complementary characteristics of both types of sensors provides much more potential. For this reason a calculation method – the integrated bundle adjustment – was developed within this thesis, where the observations of discrete object points derived from terrestrial laser scanner data and photogrammetric image data are utilised equally. This approach has several advantages: using the individual characteristics of both types of data they mutually strengthen each other in terms of 3D object coordinate determination, so that a higher accuracy can be achieved; all involved data sets are optimally co-registered; and each instrument is simultaneously calibrated. Due to the (spherical) field of view of most terrestrial laser scanners of 360° in the horizontal direction and up to 180° in the vertical direction, the integration with rotating line panoramic cameras or cameras with fisheye lenses is very appropriate, as they have a wider field of view compared to central perspective cameras. The basis for the combined processing of terrestrial laser scanner and photogrammetric image data is the strict geometric modelling of the recording instruments. Therefore geometric models, consisting of a basic model and additional parameters for the compensation of systematic errors, was developed and verified for terrestrial laser scanners and different types of cameras. Regarding the geometric laser scanner model, different approaches described in the literature were considered, as well as applying correction models known from theodolites and total stations. A particular consideration within the combined processing is the definition of the stochastic model. Since different types of observations with different underlying geometric models and different stochastic properties have to be adjusted simultaneously, adequate weights have to be assigned to the measurements. An unfavourable weighting can have a negative influence on the adjustment results. Therefore a variance component estimation procedure was implemented in the integrated bundle adjustment, which allows for an automatic determination of optimal observation weights. Hence, it becomes possible to exploit the potential of the combination of terrestrial laser scanner and photogrammetric image data completely. For the calculation of the integrated bundle adjustment, software was developed allowing various algorithmic configurations of the different data types to be applied. Numerous laser scanner, panoramic image, fisheye image and central perspective image data were recorded in different test fields and processed using the developed software. Several calculation alternatives were analysed, demonstrating the advantages and limitations of the presented method. An application example from the field of geology illustrates the potential of the algorithm in practice.
27

Automatic Retrieval of Skeletal Structures of Trees from Terrestrial Laser Scanner Data

Schilling, Anita 26 November 2014 (has links) (PDF)
Research on forest ecosystems receives high attention, especially nowadays with regard to sustainable management of renewable resources and the climate change. In particular, accurate information on the 3D structure of a tree is important for forest science and bioclimatology, but also in the scope of commercial applications. Conventional methods to measure geometric plant features are labor- and time-intensive. For detailed analysis, trees have to be cut down, which is often undesirable. Here, Terrestrial Laser Scanning (TLS) provides a particularly attractive tool because of its contactless measurement technique. The object geometry is reproduced as a 3D point cloud. The objective of this thesis is the automatic retrieval of the spatial structure of trees from TLS data. We focus on forest scenes with comparably high stand density and with many occlusions resulting from it. The varying level of detail of TLS data poses a big challenge. We present two fully automatic methods to obtain skeletal structures from scanned trees that have complementary properties. First, we explain a method that retrieves the entire tree skeleton from 3D data of co-registered scans. The branching structure is obtained from a voxel space representation by searching paths from branch tips to the trunk. The trunk is determined in advance from the 3D points. The skeleton of a tree is generated as a 3D line graph. Besides 3D coordinates and range, a scan provides 2D indices from the intensity image for each measurement. This is exploited in the second method that processes individual scans. Furthermore, we introduce a novel concept to manage TLS data that facilitated the researchwork. Initially, the range image is segmented into connected components. We describe a procedure to retrieve the boundary of a component that is capable of tracing inner depth discontinuities. A 2D skeleton is generated from the boundary information and used to decompose the component into sub components. A Principal Curve is computed from the 3D point set that is associated with a sub component. The skeletal structure of a connected component is summarized as a set of polylines. Objective evaluation of the results remains an open problem because the task itself is ill-defined: There exists no clear definition of what the true skeleton should be w.r.t. a given point set. Consequently, we are not able to assess the correctness of the methods quantitatively, but have to rely on visual assessment of results and provide a thorough discussion of the particularities of both methods. We present experiment results of both methods. The first method efficiently retrieves full skeletons of trees, which approximate the branching structure. The level of detail is mainly governed by the voxel space and therefore, smaller branches are reproduced inadequately. The second method retrieves partial skeletons of a tree with high reproduction accuracy. The method is sensitive to noise in the boundary, but the results are very promising. There are plenty of possibilities to enhance the method’s robustness. The combination of the strengths of both presented methods needs to be investigated further and may lead to a robust way to obtain complete tree skeletons from TLS data automatically. / Die Erforschung des ÖkosystemsWald spielt gerade heutzutage im Hinblick auf den nachhaltigen Umgang mit nachwachsenden Rohstoffen und den Klimawandel eine große Rolle. Insbesondere die exakte Beschreibung der dreidimensionalen Struktur eines Baumes ist wichtig für die Forstwissenschaften und Bioklimatologie, aber auch im Rahmen kommerzieller Anwendungen. Die konventionellen Methoden um geometrische Pflanzenmerkmale zu messen sind arbeitsintensiv und zeitaufwändig. Für eine genaue Analyse müssen Bäume gefällt werden, was oft unerwünscht ist. Hierbei bietet sich das Terrestrische Laserscanning (TLS) als besonders attraktives Werkzeug aufgrund seines kontaktlosen Messprinzips an. Die Objektgeometrie wird als 3D-Punktwolke wiedergegeben. Basierend darauf ist das Ziel der Arbeit die automatische Bestimmung der räumlichen Baumstruktur aus TLS-Daten. Der Fokus liegt dabei auf Waldszenen mit vergleichsweise hoher Bestandesdichte und mit zahlreichen daraus resultierenden Verdeckungen. Die Auswertung dieser TLS-Daten, die einen unterschiedlichen Grad an Detailreichtum aufweisen, stellt eine große Herausforderung dar. Zwei vollautomatische Methoden zur Generierung von Skelettstrukturen von gescannten Bäumen, welche komplementäre Eigenschaften besitzen, werden vorgestellt. Bei der ersten Methode wird das Gesamtskelett eines Baumes aus 3D-Daten von registrierten Scans bestimmt. Die Aststruktur wird von einer Voxelraum-Repräsentation abgeleitet indem Pfade von Astspitzen zum Stamm gesucht werden. Der Stamm wird im Voraus aus den 3D-Punkten rekonstruiert. Das Baumskelett wird als 3D-Liniengraph erzeugt. Für jeden gemessenen Punkt stellt ein Scan neben 3D-Koordinaten und Distanzwerten auch 2D-Indizes zur Verfügung, die sich aus dem Intensitätsbild ergeben. Bei der zweiten Methode, die auf Einzelscans arbeitet, wird dies ausgenutzt. Außerdem wird ein neuartiges Konzept zum Management von TLS-Daten beschrieben, welches die Forschungsarbeit erleichtert hat. Zunächst wird das Tiefenbild in Komponenten aufgeteilt. Es wird eine Prozedur zur Bestimmung von Komponentenkonturen vorgestellt, die in der Lage ist innere Tiefendiskontinuitäten zu verfolgen. Von der Konturinformation wird ein 2D-Skelett generiert, welches benutzt wird um die Komponente in Teilkomponenten zu zerlegen. Von der 3D-Punktmenge, die mit einer Teilkomponente assoziiert ist, wird eine Principal Curve berechnet. Die Skelettstruktur einer Komponente im Tiefenbild wird als Menge von Polylinien zusammengefasst. Die objektive Evaluation der Resultate stellt weiterhin ein ungelöstes Problem dar, weil die Aufgabe selbst nicht klar erfassbar ist: Es existiert keine eindeutige Definition davon was das wahre Skelett in Bezug auf eine gegebene Punktmenge sein sollte. Die Korrektheit der Methoden kann daher nicht quantitativ beschrieben werden. Aus diesem Grund, können die Ergebnisse nur visuell beurteiltwerden. Weiterhinwerden die Charakteristiken beider Methoden eingehend diskutiert. Es werden Experimentresultate beider Methoden vorgestellt. Die erste Methode bestimmt effizient das Skelett eines Baumes, welches die Aststruktur approximiert. Der Detaillierungsgrad wird hauptsächlich durch den Voxelraum bestimmt, weshalb kleinere Äste nicht angemessen reproduziert werden. Die zweite Methode rekonstruiert Teilskelette eines Baums mit hoher Detailtreue. Die Methode reagiert sensibel auf Rauschen in der Kontur, dennoch sind die Ergebnisse vielversprechend. Es gibt eine Vielzahl von Möglichkeiten die Robustheit der Methode zu verbessern. Die Kombination der Stärken von beiden präsentierten Methoden sollte weiter untersucht werden und kann zu einem robusteren Ansatz führen um vollständige Baumskelette automatisch aus TLS-Daten zu generieren.
28

Morfometria e Crescimento Diamétrico de Araucaria angustifolia (Bertol.) Kuntze no Planalto Sul Catarinense / Morphometry and Diametric Growth of Araucaria angustifolia (Bertol.) Kuntze in the Santa Catarina South Plateau

Klein, Danieli Regina 24 February 2017 (has links)
Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-14T12:14:47Z No. of bitstreams: 1 PGEF17MA076.pdf: 1708102 bytes, checksum: 322df030779727eab396b8c422e27499 (MD5) / Made available in DSpace on 2017-12-14T12:14:47Z (GMT). No. of bitstreams: 1 PGEF17MA076.pdf: 1708102 bytes, checksum: 322df030779727eab396b8c422e27499 (MD5) Previous issue date: 2017-02-24 / PROMOP / CAPES / Through the morphometric indices one can infer about the necessary space that the species needs to develop, maintain its growth and production rates. Allied to this, diametric growth information can portray competition in a stand, indicating the need for management practices. Objective of the proposed study to analyze the morphometry and behavior of the development and diametric increase of Araucária angustifolia through dendrochronology. In addition, data collected in the field were compared with information generated by cloud of points captured by the terrestrial Laser scanner equipment. For an analysis of the morphometry data were collected from 121 individual trees, for the purpose 127 samples and how to evaluate the information Laser 18 individuals sampled. Araucarias belong to two sites in the municipality of São José do Cerrito, in Santa Catarina. (Dc), height (h), crown height (Hc), crown radius (Rc), crown length (Cc), crown diameter (IS), the degree of slenderness (GE), the formal crown (Fc), crown ratio (Pc%), crown area (Ac) and sociological position (s) In addition to removal of increment rolls. For the morphometric relationships, 11 significant correlations were obtained and as 5 higher correlations (Dap, hic, Cc, Dc, Pc%, IA and GE) were adjusted for their determination, logarithmic E. A covariance analysis was found to exist in the morphometric relationships evaluated for each case sampled. (PS2) 0.223 m2 and dominated (PS3) 0.356 m2. For site 2, PS1 had a mean of 0.381 m2, PS2 0.360 m2 and PS3 0.300 m2. The study showed that IPAd is correlated with canopy characteristics, being a hic, Cc, Pc (%) and GE. A means of communication between variable, dendrometric and morphological means, by traditional methods of measurement and captured by Laser station, did not present significant difference between them. However, the methodologies proposed in literature are susceptible to failures, mainly, by the influence of points that do not correspond to the surface of the tree. However, the shape of the crown for each class of Dap showed that the species has different contours throughout its development stage, characterizing a conical cup in the juvenile phase, and with a maturity or shape tend to be configured in a flat way, or Then identifying a shape of umbel. For the methodologies to be comprehensive for a species, the case studies are as follows, the analyzes are welcome, the diametral amplitude is greater for the inferences, besides evaluating the viability of the images generated by the Scanning terrestrial laser scanner in the Forest mensuration / Através dos índices da morfometria pode-se inferir sobre o espaço necessário que determinada espécie necessita para se desenvolver, manter suas taxas de crescimento e produção. Aliado a isso, informações de crescimento diamétrico conseguem retratar quadro de competição em um povoamento, indicando a necessidade de práticas de manejo. O objetivo do estudo proposto foi analisar a morfometria e o comportamento do desenvolvimento e incremento diamétrico de Araucaria angustifolia através da dendrocronologia. Além disso, foram comparados dados coletados em campo com informações geradas pela nuvem de pontos captada pelo equipamento Laser scanner terrestre. Para a análise da morfometria foram coletados dados de 121 árvores individuais, para incremento foram utilizadas 127 árvores e para avaliar as informações Laser 18 indivíduos amostrados. As araucárias pertenciam a dois sítios no município de São José do Cerrito, em Santa Catarina. Foram mensuradas as variáveis: diâmetro a altura do peito (Dap), altura (h), altura de início de copa (hic), raio de copa (Rc), comprimento de copa (Cc), diâmetro de copa (Dc), índice de abrangência (IA), índice de saliência (IS), grau de esbeltez (GE), formal de copa (Fc), proporção de copa (Pc%), área de copa (Ac) e a posição sociológica (s) de cada indivíduo, além da retirada de rolos de incremento. Para as relações morfométricas obteve-se 11 correlações significativas e para as 5 maiores correlações (Dap, hic, Cc, Dc, Pc%, IA e GE) foram ajustados modelos para sua determinação, sendo caracterizados com distribuição gama e normal, e funções identidade e logarítmica. A análise de covariância demonstrou existir diferenças nas relações morfométricas avaliadas para cada sítio amostrado. Para a análise do incremento periódico anual em diâmetro (IPAd), o sítio 1, em árvores dominantes (PS1) teve média de 0,235 m2, codominantes (PS2) 0,223 m2 e dominadas (PS3) 0,356 m2. Para o sitio 2, PS1 teve média de 0,381 m2, PS2 0,360 m2 e PS3 0,300 m2. O estudo mostrou que IPAd está correlacionado com as características da copa, sendo elas, a hic, Cc, Pc(%) e o GE. A comparação entre as médias das variáveis dendrométricas e morfométricas, pelos métodos de mensuração, tradicional e captado pela estação Laser, não apresentaram diferença significativa entre si. Porém, as metodologias propostas em literatura estão suscetíveis a falhas, principalmente, pela influência de pontos que não correspondem a superfície da árvore. Já para o formato da copa para cada classe de Dap mostrou que a espécie possui diferentes contornos ao longo do seu estágio de desenvolvimento, caracterizando uma copa cônica na fase juvenil, e com a maturidade o formato tende a configurar-se de maneira plana, ou então identificando uma forma de umbela. Para que as metodologias sejam abrangentes a espécie, são necessários estudos que incluem diferentes sítios amostrais, bem como, uma amplitude diamétrica maior para gerar inferências, além de avaliar a viabilidade do uso de imagens geradas pela varredura Laser scanner terrestre na mensuração florestal
29

Utvärdering av terrester laserskanning i framställandet av en 3D-modell : Baserat på underlag från ritning och terrester laserskanning av en fackverksbro / Evaluation of terrestrial laser scanning in the creation of a 3D-model

Jansson, Tom January 2018 (has links)
De senaste åren har implementeringen av building information modeling(BIM) i anläggningsbranschen trappats upp efter att den svenska regeringen under 2015 beslutat att Trafikverket i större utsträckning ska nyttja de digitala möjligheterna med BIM. Trafikverket i form av både beställare och förvaltare av det statliga vägnätet, är en stor aktör i den svenska anläggningsbranschen och konstaterar att kravställningen mot övriga branschen är centralt för att driva utvecklingen och användandet av konceptet BIM. En sådan övergång från ett ritningsbaserat till ett objektbaserat arbetssätt kommer att påverka hela den svenska anläggningsbranschen. Målbilden är att ur ett livscykelperspektiv kunna hantera all information om anläggningen med hjälp av 3D-data. Ska de uppnå det målet krävs det i något skede att den befintliga anläggningen modelleras upp i konceptet BIM En metod som används världen över för 3D-dokumentation av komplexa objekt och miljöer är tekniken terrester laserskanning. Resultatet av en skanning är omfattande med låg mätosäkerhet, vilket lämpar sig väl med framställandet av 3D-modeller. Studien primära syfte är att utifrån resultatet från en skanning undersöka vilka skillnader det finns mellan 3D-modeller beroende på val av mätmetod. Först gjordes en nulägesanalys i form av en litteraturstudie för att kunna erhålla ett aktuellt resultat och placera studien i rätt kontext. Därefter framställdes två 3D-modeller av samma objekt, med hjälp av två olika mätmetoder som sedan jämfördes för att kunna identifiera vilka skillnader mellan modellerna. Resultatet visar att valet av mätmetod påverkade resultatet på 3D-modellen där terrester laserskanning som mätmetod kunde bidra med att förbättra kvalitén på 3D-modellen. Däremot fanns det även områden där mätmetoderna kunde komplettera varandra för ett ännu bättre resultat. / In recent years, the implementation of building information modeling (BIM) in the Swedish civil engineering industry has increased. This is due to directives from the government stating that the Swedish Transport Administration (Trafikverket), in greater occurrence, will benefit from the digital possibilities with the BIM concept. Trafikverket is the government agency responsible for the long-term planning and management of public roads, construction in the infrastructure such as tunnels and bridges, and has great influence in the Swedish civil engineering industry. They claim that the key to enhance the use and development of BIM is to raise their demands towards the rest of the industry. Transitioning from a drawing-based to an object-based approach will affect the entire industry. The idea is to be able to handle all the information in 3D-data and the BIM concept throughout the entire life cycle of the construction. To reach that ambition, the already-built constructions need to be represented as 3D-models in terms of being a part of the BIM concept. Terrestrial laser scanning is a method of measurement that is being used worldwide for 3D-documentation of complex objects and environments. The result of a scan is comprehensive with low uncertainty of measurement; therefore the method is well suited to assist in the creation of 3D-models. The primary aim of the study is to examine the differences between 3D-models, depending on the measurement method that was used to create them. An analysis of the current situation in these fields-of-study was made by a literature study to place this thesis in its proper context. Although the two 3D-models were the same exact object, they were created using two different methods of measurement. The models were compared to identify the differences between them. The study unveils that the choice of measurement method influences the results of the 3D-model, where the terrestrial laser scanning method could help to improve the quality of the final product. On the other hand, there were areas where the two methods of measurement could complement each other for even better results.
30

Influence of intra- and interspecific competition on timber quality of European beech

Höwler, Kirsten 10 September 2020 (has links)
No description available.

Page generated in 0.5414 seconds