Made available in DSpace on 2014-06-12T16:28:13Z (GMT). No. of bitstreams: 2 arquivo2062_1.pdf: 1509610 bytes, checksum: 0d01745da91f48293497491ad7abe7cb (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A utilização de dados LIDAR para a obtenção de representações fiéis a respeito da superfície terrestre vem, nos últimos anos, consagrando-se como uma das alternativas mais viáveis e recorridas para se adquirir o MDS (Modelo Digital de Superfície) e principalmente do MDT (Modelo Digital do Terreno). Essa aceitação se justifica em especial pelo auto grau de automação na aquisição e processamento de dados, mas também se destaca a notável resolução altimétrica e planimétrica que os dados LIDAR oferecem. A obtenção automática do MDT a partir desses dados ocorre por meio de um processo conhecido por classificação, que consiste na remoção virtual dos pontos de um MDS que, em principio, não pertencem à superfície do terreno propriamente dita, mas sim às informações que se encontram sobre o solo, tais como edificações e elementos da própria natureza. Esse tema se trata de uma questão atual e ainda não concluída pelos principais centros de pesquisa nessa área do conhecimento em nível mundial. Nesse sentido, o presente trabalho, considerando aspectos visuais e numéricos, apresenta um estudo comparativo entre quatro métodos de filtragem e classificação automática de pontos que constituem o MDS oriundo dos dados LIDAR, a fim de se obter o respectivo MDT de quatro regiões distintas do Centro Politécnico da Universidade Federal do Paraná UFPR em Curitiba, Paraná Brasil. Os métodos implementados e variações propostas são pertinentes às principais linhas de pesquisa à respeito do assunto. A partir da análise dos resultados apresentados, discutidos e pontuados os principais problemas encontrados, é possível afirmar que a filtragem e classificação de dados LIDAR para geração automática do MDT é um fato bem sucedido, uma vez que os produtos gerados apresentam notável coerência visual e indicadores numéricos considerados satisfatórios

Made available in DSpace on 2014-06-12T16:31:16Z (GMT). No. of bitstreams: 2 arquivo525_1.pdf: 1509610 bytes, checksum: 0d01745da91f48293497491ad7abe7cb (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A utilização de dados LIDAR para a obtenção de representações fiéis a respeito da superfície terrestre vem, nos últimos anos, consagrando-se como uma das alternativas mais viáveis e recorridas para se adquirir o MDS (Modelo Digital de Superfície) e principalmente do MDT (Modelo Digital do Terreno). Essa aceitação se justifica em especial pelo auto grau de automação na aquisição e processamento de dados, mas também se destaca a notável resolução altimétrica e planimétrica que os dados LIDAR oferecem. A obtenção automática do MDT a partir desses dados ocorre por meio de um processo conhecido por classificação, que consiste na remoção virtual dos pontos de um MDS que, em principio, não pertencem à superfície do terreno propriamente dita, mas sim às informações que se encontram sobre o solo, tais como edificações e elementos da própria natureza. Esse tema se trata de uma questão atual e ainda não concluída pelos principais centros de pesquisa nessa área do conhecimento em nível mundial. Nesse sentido, o presente trabalho, considerando aspectos visuais e numéricos, apresenta um estudo comparativo entre quatro métodos de filtragem e classificação automática de pontos que constituem o MDS oriundo dos dados LIDAR, a fim de se obter o respectivo MDT de quatro regiões distintas do Centro Politécnico da Universidade Federal do Paraná UFPR em Curitiba, Paraná Brasil. Os métodos implementados e variações propostas são pertinentes às principais linhas de pesquisa à respeito do assunto. A partir da análise dos resultados apresentados, discutidos e pontuados os principais problemas encontrados, é possível afirmar que a filtragem e classificação de dados LIDAR para geração automática do MDT é um fato bem sucedido, uma vez que os produtos gerados apresentam notável coerência visual e indicadores numéricos considerados satisfatórios

Submitted by Amanda Silva (amanda.osilva2@ufpe.br) on 2015-03-05T15:17:55Z No. of bitstreams: 2 DISSERTAÇÃO Mirele Viegas da Silva.pdf: 7784954 bytes, checksum: 56193e4339b0daaaa3548129ff171819 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-05T15:17:55Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Mirele Viegas da Silva.pdf: 7784954 bytes, checksum: 56193e4339b0daaaa3548129ff171819 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-06-04 / O laser scanner aerotransportado, ALS (Airborne Laser Scanner), também conhecido como LIDAR (Light Detection and Ranging), consiste atualmente numa das tecnologias mais utilizadas para a aquisição de enormes volumes de dados num curto período de tempo. Essa tecnologia envolve a emissão de um pulso eletromagnético em direção à superfície tendo como produto as coordenadas plani-altimétricas e a intensidade do feixe refletido pelo objeto atingido. A posição tridimensional somente pode ser calculada, se em qualquer momento, a posição e orientação do sistema de laser se façam conhecidos com respeito a um sistema de coordenadas, isso é possível devido ao fato que o sistema dispõe de GPS (Global Positioning System)/GNSS (Global Navigation Satellite System) e INS (Inertial Navigation System), auxiliando diretamente no georreferenciamento das imagens e nuvens de pontos adquiridas. O conjunto de dados do laser scanner é uma alternativa poderosa para ser aplicado na otimização de técnicas de mapeamento fotogramétrico, permitindo um ótimo desempenho para extrair informação espacial tridimensional. A imagem fotogramétrica permite, por sua vez, a extração exata de feições planimétricas. Este trabalho descreve uma metodologia para avaliar feições planimétricas em áreas urbanas obtidas com a tecnologia laser scanner aerotransportado tendo, como objetivo, estudar a qualidade posicional planimétrica das feições pontuais em imagens provenientes do laser scanner (imagens de intensidade), através da comparação da saída de dados deste com os dados provenientes do método fotogramétrico aéreo e topográfico. Na presente pesquisa, foi concentrada a detecção principalmente de feições planimétricas de telhados e arruamentos. O método de avaliação da acurácia foi baseado na análise de pontos e medidas de feições lineares obtidas com imagens de intensidade do sistema laser scanner comparadas com medidas obtidas em levantamento GNSS e restituição fotogramétrica de duas áreas localizada no Campus da Universidade Federal de Pernambuco e no bairro da Macaxeira, município de Recife/PE, avaliando de acordo com o Padrão de Exatidão Cartográfico para Produtos Cartográficos Digitais – PEC PCD.

Delivery of sediment to beach-dune complexes along the northern California coast, as elsewhere, is controlled by littoral and aeolian processes governed largely by oceanic and meteorological conditions such as wind speed and direction, wave characteristics and water level fluctuations. Furthermore, patterns of sediment deposition on foredunes are controlled by the zonation, density and physical structure of dominant vegetation assemblages. This study explores the link between varying oceanic, meteorological and ecological patterns and coastal foredune morphodynamics at a site within the Humboldt Bay National Wildlife Refuge (HBNWR) near Arcata, CA, to provide coastal managers a local context of foredune erosion and accretion. At a site within the HBNWR a 75-year north to south alongshore gradient in foredune response was observed during the study period. Foredunes in the north experience seaward progradation (up to +0.51 m a-1) and greater sediment volumes then southern foredunes, characterized by foredune retreat (up to -0.49 m a-1) and larger erosive feature areas. Seasonal signatures of a previously observed bi-directional littoral drift partially inform the interpretation of an alongshore gradient in foredune position. In the summer, wind and wave directions were out of the NNW, combined with north to south littoral drift and significant sediment input into the northern beaches. During the winter, the dominant drift direction was from the south to the north, accompanied by large waves, high water levels and beach erosion. Following a comprehensive morpho-ecological model of foredune evolution (Hesp, 1988; 2002), greater foredune volumes, dense vegetation and seaward progradation are indicative of stage 1 foredunes. Transitioning to the south, lower vegetation densities and seaward retreat support a classification of stage 3 developed foredunes, characterized by shorter, more hummocky morphologies. Meteorological patterns and disturbance to vegetation concurrently influence foredune response and recovery to erosive wind, wave and water level events. As such, seasonal to interannual patterns of foredune morphodynamics may be altered following periods of both environmental and human induced vegetation disturbance (i.e., seasonal phenology, dynamic restoration). At a section of foredune in the northern HBNWR, a dynamic restoration project was implemented with the first stages of vegetation removal occurring in August, 2015. In a year following vegetation disturbance through preliminary stages of restoration an annual sediment budget examination indicates net accretion on the foredune (+0.54 m3 m-2) while net erosion occurred on the beach (-0.38 m3 m-2). At smaller seasonal scales site-wide erosion occurred in the winter due to high-water and wave run-up recorded during intense storms. Summer monitoring reveals site-wide accretion due to beach rebuilding, heightened aeolian activity and an increase in vegetation cover. As such, seasonal sediment budgets that influence longer-term patterns of foredune development may be primarily controlled by the amount of sediment available on the beach for aeolian transport and secondarily by localized presence/absence of vegetation. Results of this study provide insight into the impact of continued coastal disturbance on foredune morphodynamics, around which a framework for future vegetation management projects may be implemented. / Graduate

Les forêts représentent une ressource naturelle de grande valeur écologique et d'une valeur économique considérable. En fait, la superficie occupée par la forêt à l'échelle planétaire est estimée à 4 milliards d'hectares, soit 30% de la surface terrestre . À lui seul, le Canada possède 10% de ces ressources forestières mondiales, et s'est vu conférer le titre du plus grand exportateur de produits forestiers en 2006 (RNCan, 2009). Vue l'importance de la superficie occupée et le besoin de connaître davantage les paramètres de structure des arbres et des peuplements afin d'en assurer une gestion adaptée, il appert essentiel de recourir à des outils technologiques avant-gardistes. À cet égard, l'utilisation du lidar (light detection and ranging) terrestre imageur en foresterie suscite un intérêt sans cesse grandissant, et ce, afin de bonifier les inventaires sur le terrain. Des paramètres de structure tels que la hauteur de l'arbre, le diamètre à hauteur de poitrine (DHP ) et le défilement de la tige et le volume peuvent s'avérer être des facteurs décisifs à la gestion des ressources forestières et à leur suivi. Divers projets de recherche ont permis de développer des outils de traitement de données lidars en milieu forestier, dont celui de la compagnie TreeMetrics en Irlande et celui de la Chair of Forest Yield Science de la Technische Universitét Munchen en Allemagne. Dans le cadre du présent projet, l'objectif principal vise à explorer le potentiel de ces deux outils (Autostem et R-Routine) afin de traiter les données lidars provenant de divers milieux forestiers localisés au Canada et en Allemagne. Le défi majeur consiste à traiter les données de milieux naturels et hétérogènes provenant des sites d'étude localisés en Gaspésie (Québec, Canada). La complexité de ces sites représente une limite importante, principalement quant à la présence du sous-bois, à la densité du couvert et à la présence de branches dans la partie inférieure du tronc. Les mesures de la hauteur, du DHP et du défilement obtenues avec les deux logiciels pour des sites hétérogènes et homogènes sont confrontées aux mesures manuelles acquises sur le terrain, et ce, pour les 39 arbres étudiés. Une synthèse des forces et limites du lidar terrestre dans un contexte d'opérationnalité en milieu forestier est également présentée afin d'en arriver à un protocole de prise de mesures. Suite au traitement des données, il a été possible d'obtenir une précision de l'ordre du mètre pour ce qui est de la hauteur , et ce, avec les deux logiciels, et dans les deux types de peuplements. Pour le DHP, avec le logiciel Autostem, une sous-estimation moyenne de 5,8 cm a été observée pour les peuplements hétérogènes, comparativement à 6,5 cm pour les peuplements homogènes, alors qu'avec le logiciel R-Routine, la tendance est inversée, soit une surestimation de 3,5 cm pour les arbres de peuplements hétérogènes et 3,0 cm pour ceux de peuplements homogènes. Néanmoins, tout comme pour la hauteur, l'erreur moyenne du DHP en milieu hétérogène et homogène dans le cadre de cette étude est comparable , et ce, sans égard au logiciel utilisé. Finalement, les résultats de défilement obtenus sont contraires à ce qu'on aurait pu s'attendre, les erreurs des défilements en milieu hétérogènes, sont légèrement inférieures à celles en milieu homogène. Quant aux forces et limites du lidar, notons tout d'abord l'avantage d'une représentation 3D des peuplements qui soit non subjective, de la possibilité de conserver ces données pour éventuellement les traiter à nouveau afin d'extraire d'autres paramètres avec des algorithmes, ou de faire un suivi temporel de l'évolution d'un peuplement. D'autre part, le temps d'acquisition représente un atout majeur de nombreux modèles de lidars, bien que leur utilisation puisse être restreinte en raison de l'accessibilité au site parfois restreinte en raison de la taille et du poids de l'équipement. De plus, bien que les scans puissent être effectués à tout moment dans l'année, il est préférable de les faire en absence de feuille, soit au printemps ou à l'automne; soit avant le débourrage ou après la chute des feuilles. Néanmoins, l'atout majeur des données du lidar terrestre réside dans le potentiel d'automatisation de l'extraction des paramètres qui permet, entre autres, d'obtenir la reconstruction des tiges , d'évaluer le défilement de la tige, le DHP et la hauteur, et ce, avec une relativement bonne précision, sans abattre les arbres.

The climate of the Wester Ross region of NW Scotland is particularly sensitive to fluctuations in the strength and latitude of the North Atlantic Gulf Stream. This was particularly apparent during the last deglaciation (14.7-12.9 ka), when overall climatic amelioration was interrupted by periods of cooling, the most significant being a 1.2 ka return to glacial conditions during the Younger Dryas (12.9-11.5 ka). Glacial readvances during these cooling episodes left behind numerous geomorphological features, which have been mapped and interpreted through a variety of methods, including fieldwork observations, aerial photography and digital elevation models, to form a detailed reconstruction of the style and timing of deglaciation. These methods were augmented by the study of 3D digital models, produced by combining 5cm resolution, Light Detection and Ranging (LiDAR) scans with colour photography, leading to the production of a detailed geomorphological map of a cirque formation in Torridon, Wester Ross, which was covered by an ice-sheet at the Last Glacial Maximum, and experienced localised ice flow during subsequent deglaciation and readvances. Six statistically comparable cosmogenic 10Be bedrock exposure ages give a Younger Dryas age for sites in Torridon and Applecross (Wester Ross), and have also been used to constrain the vertical extent of these ice fields. Reconstructions of these ice bodies revealed that the Torridon ice field (mean ELA, 482m) covered ~100km2, over twice the surface area covered by the Applecross ice field (~43km2). This could have resulted from the survival of ice in Torridon prior to the onset of the Younger Dryas cooling, and is tentativelty supported by pre-Younger Dryas cosmogenic 10Be exposure ages from this study and previous studies, which imply that ice existed close to the Wester Ross coastline and within central Torridon between 14-13ka. The Applecross ice field mean ELA (361m) was lowered by the presence of independent glaciers, which formed in low-lying troughs as snow was efficiently transferred to the NE by prevailing SW winds. Using empirical values from a global dataset, average annual Younger Dryas palaeoprecipitation values for the Torridon and Applecross ELAs are 2010 ± 266 and 2312 ± 534 mm a-1 respectively, suggesting a wetter climate than today. Palaeoprecipitation calculated using equations based on a climate model of NW Scotland, yield lower values between 1005 ± 67 mm a-1 and 1758 ± 118 mm a-1 for the Torridon ELA and 1205 ± 233 mm a-1 to 2109 ± 407 mm a-1 for the Applecross ELA, perhaps a more reliable estimate which reflect enhanced continentaility, promoted by the formation of sea ice on the NE Atlantic seaboard during the Younger Dryas.Despite the rapid warming observed in palaeotemperature proxies, studies of glacial geomorphology and basal shear stress suggest that initial deglaciation was slow, oscillatory and warm-based, leading to the formation of prominent retreat moraines in the lower valleys. This prolonged transition can be related to the northward migration of sea ice and the gradual reintroduction of a Gulf Stream-dominated maritime climate. Ice remaining in the central area down-wasted in-situ as the regional ELA increased, creating hummocky landscape. Finally, cosmogenic 10Be exposure ages indicate that glaciers (probably characerised by a polythermal regime) retreated into the high north-facing corries at approximately 11.8ka, depositing a series of flutes.

Global modeling of gross primary production (GPP) is a critical component of climate change research. On local scales, GPP can be assessed from measuring CO₂ exchange above the plant canopy using tower-based eddy covariance (EC) systems. The limited footprint inherent to this method however, restricts observations to relatively few discrete areas making continuous predictions of global CO₂ fluxes difficult. Recently, the advent of high resolution optical remote sensing devices has offered new possibilities to address some of the scaling issues related to GPP using remote sensing. One key component for inferring GPP spectrally is the efficiency (ε) with which plants can use absorbed photosynthetically active radiation to produce biomass. While recent years have seen progress in measuring ε using the photochemical reflectance index (PRI), little is known about the temporal and spatial requirements for up-scaling these findings continuously throughout the landscape. Satellite observations of canopy reflectance are subject to view and illumination effects induced by the bi-directional reflectance distribution function(BRDF) which can confound the desired PRI signal. Further uncertainties include dependencies of PRI on canopy structure, understorey, species composition and leaf pigment concentration. The objective of this research was to investigate the effects of these factors on PRI to facilitate the modeling of GPP in a continuous fashion. Canopy spectra were sampled over a one-year period using an automated tower-based, multi-angular spectroradiometer platform (AMSPEC), designed to sample high spectral resolution data. The wide range of illumination and viewing geometries seen by the instrument permitted comprehensive modeling of the BRDF. Isolation of physiologically induced changes in PRI yielded a high correlation (r²=0.82, p<0.05) to EC-measured ε, thereby demonstrating the capability of PRI to model ε throughout the year. The results were extrapolated to the landscape scale using airborne laser-scanning (light detection and ranging, LiDAR) and high correlations were found between remotely-sensed and EC-measured GPP (r²>0.79, p<0.05). Permanently established tower-based canopy reflectance measurements are helpful for ongoing research aimed at up-scaling ε to landscape and global scales and facilitate a better understanding of physiological cycles of vegetation and serve as a calibration tool for broader band satellite observations. / Forestry, Faculty of / Graduate

Lidar has the ability to supplant or compliment many current measurement technologies in ocean optics. Lidar measures Inherent Optical Properties over long distances without impacting the orientation and assemblages of particles it measures, unlike many systems today which require pumps and flow cells. As an active sensing technology, it has the benefit of being independent of time of day and weather. Techniques to interpret oceanographic lidar lags behind atmospheric lidar inversion techniques to measure optical properties due to the complexity and variability of the ocean. Unlike in the atmosphere, two unknowns in the lidar equation backscattering at 180o (𝛽𝜋) and attenuation (c) do not necessarily covary. A lidar system developed at the Harbor Branch Oceanographic Institute is used as a test bed to validate a Monte-Carlo model to investigate the inversion of optical properties from lidar signals. Controlled tank experiments and field measurements are used to generate lidar waveforms and provide optical situations to model. The Metron EODES backscatter model is used to model waveforms. A chlorophyll based forward optical model provides a set of 1500 unique optical situations which are modeled to test inversion techniques and lidar geometries. Due to issues with the lidar system and model the goal of validating the model as well as a more mature inversion experiment were not completed. However, the results are valuable to show the complexity and promise of lidar systems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

The use of terrestrial laser scanner in forestry seems to be promising technology for new findings about forest ecosystem together with precise information for forest managers and planners. With new technology comes also new methodology of data acquisition, data processing and presentation of results. In this thesis are proposed methodological aspects of scanning setup if forest with analysis of two main obstacles - terrain and tree stems together with estimation of synergic effect of additional scan and optimal distance of such scan. In the following section software for processing of TLS data from forest environment - 3D Forest - is introduced and briefly described. In the last part original and early attempt of the below ground tree biomass reconstruction and volume estimation using TLS data is presented as a part of coppice forest study.

Speckles are a phenomenon which often appears in situations involving lasers. Their properties can be used as an advantage but in the case of LiDAR applications, they’re purelydestructive. The peaks and troughs of the intensity distribution across the collimatinglens can be seen as variations in signal strength at the detector. The project presented inthis paper examines the properties of these intensity patterns and how their various sizeseffects the sampled signal. This is done by experimental measurements with the use ofa coherent LiDAR accompanied by a simulation to recreate and explain the behavioursof the results obtained in the measurements. The study shows a simulation which exclusively takes speckle dependence into account successfully produce similar results asphysical experiments. The varying of subjective speckle sizes on the detector was foundto have little effect on the sampled signal quality, though the improved averaging of thesmaller speckles caused the signal strength to shift in tranquil manner.