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  • 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.
1

Proposta de metodologia para definição de um modelo digital de elevação para monitoramento de áreas de inundação

Silva, Robert Martins da 01 October 2017 (has links)
Submitted by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2018-02-06T15:00:54Z No. of bitstreams: 1 Robert Martins da Silva - 2017.pdf: 90829743 bytes, checksum: 03eef7ebec5e626e2c74eddd8bf63508 (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2018-02-06T15:33:35Z (GMT) No. of bitstreams: 1 Robert Martins da Silva - 2017.pdf: 90829743 bytes, checksum: 03eef7ebec5e626e2c74eddd8bf63508 (MD5) / Made available in DSpace on 2018-02-06T15:33:35Z (GMT). No. of bitstreams: 1 Robert Martins da Silva - 2017.pdf: 90829743 bytes, checksum: 03eef7ebec5e626e2c74eddd8bf63508 (MD5) Previous issue date: 2017-10-01 / O conhecimento do relevo terrestre sempre foi de grande importância para a humanidade, e o modo de sua representação é objeto de constante e múltiplos estudos. Objetivo desse trabalho foi a utilização de métodos geodésicos para eleboração de um modelo digital de elevação integrado com dados hidrológicos para monitoramento das áreas afetadas pelas inundações do Rio Uruguai na cidade de Itaqui, Rio Grande do Sul, que periodicamente sofrem perdas e grandes gastos devido as recorrentes inundações. Para tanto neste trabalho é aplicado uma metodologia baseada na associação de dados provenientes de diferentes fontes (dados de levantamento geodésico, altimétrico, série histórica de dados hidrológicos), e que juntos retornam um produto final preciso e confiável. Para início do trabalho foi realizado a vinculação das cotas do rio ao sistema geodésico brasileiro através do nivelamento geométrico entre uma RN de referência e as réguas linimétricas do rio. Na segunda parte do trabalho foi aplicada técnicas de posicionamento geodésico dentro da região de estudo e posterior processamento e análise dos dados obtidos. Nessa etapa também realizou-se a conversão de altitudes geométricas em ortométricas e sua correção com o uso de um modelo geoidal. A terceira etapa do trabalho consistiu na geração de modelos digitais com diferentes interpoladores em ambiente SIG e posteriormente foi realizada uma análise estatística para validação e classificação dos modelos por meio do Software GeoPec desenvolvido especificamente para avaliação de dados espaciais. E por último a validação do MDE resultante através da comparação com trabalhos já realizados e com uma aplicação direta em um evento ocorrido no ano de 2017. A aplicação dessa metodologia permitiu a obtenção de um modelo digital de elevação preciso e acurado classificado dentro das normativas da cartografia nacional. Tal resultado justifica que a aplicação da metodologia proposta pode ser empregada por toda área urbana do município de Itaqui retornar algum suporte aos gestores visto que a metodologia apresentou resultados satisfatórios, necessitando porém de alguns ajustes e complementos de forma a se tornar mais eficiente. / The knowledge of earthly relief has always been of great importance to mankind, and the mode of its representation is the object of constant and multiple studies.The objective of this work was the use of geodetic methods for the elaboration of a digital elevation model integrated with hydrological data to monitor the areas affected by the Uruguay River floods in the city of Itaqui, Rio Grande do Sul, which periodically suffer losses and large expenses due to recurrent floods. For this purpose, a methodology based on the association of data from different sources (geodetic survey, altimetric data, historical series of hydrological data) is applied, and together they return an accurate and reliable final product. For the beginning of the work the linking of the river quotas to the Brazilian geodetic system was done through the geometric leveling between a reference RN and the linimetric rules of the river. In the second part of the work, geodetic positioning techniques were applied within the region of study and later processing and analysis of the data obtained. In this stage also the conversion of geometric altitudes in ortometric and its correction with the use of a geoidal model was realized. The third stage of the work consisted in the generation of digital models with different interpolators in GIS environment and later a statistical analysis was performed for the validation and classification of the models through the GeoPec Software developed specifically for the evaluation of spatial data. And finally, the validation of the resulting MDE through the comparison with works already carried out and with a direct application in an event occurred in the year 2017. The application of this methodology allowed to obtain a digital model of accurate and accurate elevation classified within the norms of the cartography. This result justifies that the application of the proposed methodology can be used by all urban areas of the municipality of Itaqui to return some support to the managers since the methodology presented satisfactory results, however, requiring some adjustments and complements in order to become more efficient.
2

A height datum for Uganda based on a gravimetric quasigeoid model and GNSS/levelling

Ssengendo, Ronald January 2015 (has links)
This study is devoted to the determination of a high resolution gravimetric geoid model for Uganda based on the optimal combination of terrestrial and satellite gravity anomalies using the method of Least Squares Modification of Stokes’ formula with additive corrections. Specifically the study investigates the current status of the existing Uganda Vertical Network relative to the requirements of a modern height datum and includes a detailed evaluation and validation of terrestrial gravity data, several digital elevation models and some recent global geopotential models. Finally a new height datum based on a gravimetric quasigeoid model and Global Navigation Satellite Systems (GNSS)/levelling is proposed. In this thesis, the Uganda Gravimetric Geoid Model 2014 (UGG2014) is computed from several datasets which, include 7839 terrestrial gravity data points from the International Gravimetric Bureau, the 3 arc second Shuttle Radar Topography Mission digital elevation model and a recent Gravity field and steady-state Ocean Circulation Explorer-only global geopotential model. To compensate for the missing gravity data in the target area, the surface gravity anomalies extracted from the World Gravity Map 2012 were used. Outliers in the terrestrial gravity data were detected using the cross-validation technique which, also estimated the accuracy of the remaining terrestrial gravity data as 9 mGal. Based on 12 GNSS/levelling data points distributed over Uganda, the root mean square fit of UGG2014 before and after the 4-parameter fit is 16 cm and 9 cm, respectively. The study has revealed that the heights of the Uganda Vertical Network are normal-orthometric heights for which the quasigeoid is the closest approximation to the zero reference surface. Consequently, the Uganda Gravimetric Quasigeoid Model 2014 (UGQ2014) was derived from the UGG2014 with the quasigeoid-geoid separation computed from the Earth Gravitational Model 2008 complete to degree/order 2160 of spherical harmonics. The root mean square fit of UGQ2014 versus GNSS/levelling is 15 cm and 8 cm before and after the 4-parameter fit, respectively, which shows that the quasigeoid model fits GNSS/levelling better than the geoid model. Thus a new height datum based on UGQ2014 and GNSS/levelling was determined as a practical solution to the determination of heights directly from GNSS. Evaluated with 4 independent GNSS/levelling points, the root mean square fit of the new height datum is 5 cm better than using the quasigeoid model alone. With an average parts-per-million of 29 in the relative test, the new height datum satisfies the precision and accuracy requirements of third order precise levelling. Overall, the results show that UGG2014 and UGQ2014 agree considerably better with GNSS/levelling than any other recent regional/global gravimetric geoid models. Therefore, both gravimetric solutions are a significant step forward in the modelling of a “1-cm geoid” over Uganda given the poor quality and quantity of the terrestrial gravity data used for computation. / <p>QC 20150831</p>
3

Determination of a gravimetric geoid model of Kazakhstan using the KTH-method

Inerbayeva (Shoganbekova), Daniya January 2010 (has links)
This study work deals with the determination of the gravimetric geoid model for Kazakhstan by using the KTH-method. A number of data sets were collected for this work, such as the gravity anomalies, high-resolution Digital Elevation Model (DEM), Global Geopotential Models (GGMs) and GPS/Levelling data. These data has been optimally combined through the KTH approach, developed at the Royal Institute of Technology (KTH) in Stockholm. According to this stochastic method, Stokes’ formula is being used with the original surface gravity anomaly, which combine with a GGM yields approximate geoid heights. The corrected geoid heights are then obtained by adding the topographic, downward continuation, atmospheric and ellipsoidal corrections to the approximate geoid heights. To compute the geoid model for Kazakhstan as accurately as possible with available data set different numerical tests have been performed: Choice of the best fit geopotential model in the computation area Investigations for the best choice of the initial condition for determination of the least-squares parameters Selection of the best parametric model for reducing the effect of the systematic error and data inconsistencies between computed geoid heights and GPS/Levelling heights.  Finally, 5'x5' Kazakh gravimetric geoid (KazGM2010) has been modelled.
4

Testes sobre a eficiência do modelo do geopotencial EGM2008 na cidade de Porto Alegre

Nunes, Vagner Conceição January 2010 (has links)
Este estudo apresenta o teste da eficiência do Earth Global Model 2008 (EGM2008) na geração de um modelo geoidal local, através da compatiblização com a ondulação obtida por posicionamento GPS (Global Positioning System) em 63 Referências de Nível (RN’s) localizadas no município de Porto Alegre, Rio Grande do Sul. O objetivo geral da dissertação foi analisar a exatidão do modelo geoidal gerado a partir dos coeficientes do modelo geopotencial EGM2008 para nivelamento por GPS no município de Porto Alegre e os objetivos específicos foram: a avaliação do modelo na região de Porto Alegre, a comparação das ondulações geoidais do EGM2008 (NEGM2008) com as ondulações geoidais em 63 RN’s (NGPS), o ajustamento da componente sistemática do geoide que é a diferença entre NEGM2008 e NGPS e a geração do modelo geoidal local compatibilizado para Porto Alegre. O método adotado apresenta as seguintes etapas: cálculo das ondulações geoidais nas RN’s; eliminação de erros grosseiros; geração do modelo geoidal através dos dados do EGM2008 com resolução de 7” de arco; cálculo da componente sistemática do geoide; ajustamento da componente sistemática através de transformação por polinômio de 2° grau com seis parâmetros pelo Método dos Mínimos Quadrados (MMQ). Os resultados obtidos foram: os parâmetros que compatibilizam o modelo geoidal global com o local e modelo geoidal local compatibilizado no formato raster, contendo as ondulações geoidais para todo o município. O novo modelo apresentou erro médio de 1,9 cm e desvio padrão de 7,2 cm. Os resultados da dissertação confirmam que é possível reduzir o erro associado ao modelo global através dos procedimentos adotados. Dessa maneira, conclui que o método utilizado reduziu o valor médio da componente sistemática de 15,4 cm para 1,9 cm após o ajustamento. / This study presents the Earth Global Model 2008’s (EGM2008) efficiency test on the conception of a local geoid model. The results were acquired through the undulation compatibility obtained by GPS (Global Positioning System) in 63 Bench Mark (BM) located in Porto Alegre, Rio Grande do Sul state, Brazil. The aim of this research was to analyze the accuracy of the geoid model generated from the geopotential model EGM2008’s coefficients to GPS leveling in Porto Alegre. The specific goals were the evaluation of the model in Porto Alegre region’s, the comparison between the EGM2008 (NEGM2008) geoid undulations and the geoid undulations in 63 BM (NGPS), and the adjustment of geoid’s systematic component, that is the difference between NEGM2008 and NGPS and the local geoid model’s conception to Porto Alegre. The method used presents the following steps: geoid undulation on RN’s’s computation; elimination of gross errors; geoid model’s conception through EGM2008’s data with resolution of 7” of arch; geoid’s systematic component computation; adjustment of the systematic component through transformation of 2nd degree polynomial with six parameters by the method of Least Squares. The results were: the parameters that make the models global and local compatible, and local geoid model compatible in raster format, containing the geoid undulations for the entire municipality. The new model showed 1.9 of mean error and 7.2 cm of standard deviation. Through the procedures adopted, the dissertation results’ confirm that it is possible to reduce the error associated of the the global model. Therefore, the conclusion is that the method used reduced the mean error of the systematic component from 15,4 cm to 1.9 cm, after the adjustment.
5

Expérimentation d’un gravimètre mobile léger et novateur pour la mesure du champ de gravité en fond de mer / Experimentation of a light and innovative mobile gravimeter for the measurement of the gravity field in the seabed

Roussel, Clément 19 June 2017 (has links)
L’un des défis majeurs relevé par la gravimétrie moderne consiste en la détermination de modèles mathématiques et de cartes numériques du champ de gravité de la Terre dont la fiabilité est identique quelle que soit l’échelle spatiale considérée en domaines terrestre, littoral, marin et sous-marin. Aujourd’hui, les harmoniques de haut degré correspondant aux courtes longueurs d’onde du champ de gravité sont encore affectés de grandes incertitudes de par la diversité et les différences de précision et de résolution des techniques gravimétriques permettant de les atteindre. Le principal obstacle à l’amélioration de la résolution et la précision des modèles vient de ce que les systèmes de gravimétrie et gradiométrie mobiles, seuls instruments qui permettent des acquisitions à précision et à résolution spatiale homogènes, demeurent encore encombrants et gros consommateurs d’énergie, ce qui interdit en particulier leur installation sur des drones terrestres, aériens, navals de surface et sous-marins. L’intérêt de ce type de porteur est de pouvoir opérer des acquisitions très proches des sources ce qui accroît considérablement la restitution des variations locales de la gravité. Le développement d’un nouveau type de capteur gravimétrique à faible encombrement et moindre consommation énergétique apparaît donc indispensable pour répondre à la problématique posée par la mesure des courtes longueurs d’onde du champ de gravité.Dans le cadre de ses activités de recherche en gravimétrie, le Laboratoire de Géomatique et Foncier (Cnam/GeF EA 4630), en collaboration avec le Laboratoire de Recherche en Géodésie (LAREG) de l’Institut National de l’information Géographique et forestière (IGN), le Laboratoire Domaines Océaniques (LDO, UMR CNRS 6538, UBO), l’Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER) et le Service Hydrographique et Océanographique de la Marine (SHOM), développe un instrument novateur qui permet la mesure dynamique du champ de gravité terrestre en fond de mer.Le système baptisé GraviMob (système de Gravimétrie Mobile) ne nécessite pas de plateforme stabilisée et se fixe rigidement dans l’habitacle du véhicule porteur, en l’occurrence, un submersible autonome. Le cœur du système est constitué de triades d’accéléromètres, permettant une mesure vectorielle de l’accélération de pesanteur. Un traitement des mesures par filtrage de Kalman, intégrant les données de position et d’orientation du véhicule porteur, réalise la restitution du champ de pesanteur dans un référentiel adapté à son interprétation et son exploitation. Ce prototype instrumental a été expérimenté en Mer Méditerranée au cours de l’année 2016, à l’aplomb de profils gravimétriques de surface acquis antérieurement par le SHOM. La comparaison du signal gravimétrique obtenu en fond de mer avec les données du SHOM indique une répétabilité de la tendance générale du signal gravimétrique à 5 mGal près.Ce manuscrit aborde successivement, l’établissement de l’équation d’observation du système GraviMob, l’étalonnage et l’orientation des accéléromètres du capteur, la stratégie d’estimation du champ de pesanteur par un filtre de Kalman intégrant un modèle d’évolution des composantes du champ de pesanteur et un modèle d’observation tenant compte du bruit de mesure, le traitement et l’analyse des mesures acquises lors de son expérimentation en Mer Méditerranée, puis la comparaison du signal gravimétrique obtenu avec les données de référence. / One of the major challenges of modern gravimetry consists in determining mathematical models and digital maps of the Earth’s gravity field, the reliability of which is identical whatever the spatial scale considered in terrestrial, coastal, marine and submarine domains. Today, the harmonics of high degree corresponding to the short wavelengths of the gravity field are still affected by great uncertainties due to the diversity and the differences in precision and resolution of the gravimetric techniques making it possible to reach them. The main obstacle to improve the resolution and accuracy of models is that gravimetry and gradiometry mobile devices, the only instruments that allow homogeneous precision and spatial resolution acquisitions, are still bulky and energy-intensive, which prohibits their installation on terrestrial, aerial, surface and submarine drones. The interest of this type of carrier is to make acquisitions very close to the sources which considerably increases the restitution of the local variations of the gravity. The development of a new type of gravimetric sensor with small size and lower energy consumption appears therefore essential to answer the problematic posed by the measurement of the short wavelenghts of the gravity field.As part of its research in gravimetry, the Laboratoire Géomatique et Foncier (Cnam/GeF EA 4630), in collaboration with the Laboratory for Research Geodesy (LAREG) of the National Institute for Geographic and Forest Information (IGN), the Oceanic Domains Laboratory (LDO, UMR, CNRS 6538, UBO), the French Research Institute for the Exploitation of the Sea (IFREMER) and the Marine Hydrographic and Oceanographic Service (SHOM), develops an innovative instrument which allows the dynamic measurement of the Earth’s gravity field in the subsea domain.The system, called GraviMob (Gravimetry Mobile System), does not require a stabilized platform and is rigidly attached to the carrier vehicule, in this case an Autonomous Underwater Vehicule (AUV). The heart of the system consists of triads of accelerometers, allowing a vector measurement of the gravity. A Kalman filter, integrating the position and orientation data of the carrier vehicle, performs the estimation of the gravity field in a frame adapted to its interpretation. This instrumental prototype has been tested in the Mediterranean Sea during the year 2016. The comparison of the gravimetric signal obtained near the seabed with the surface gravimetric profiles, previously acquired by the SHOM, indicates a repeatability of the general trend of the gravimetric signal to within 5 mGal.This manuscript deals successively with the establishment of the observation equation of the GraviMob system, the calibration and orientation of the accelerometers, the gravity field estimation strategy by a Kalman filter, integrating an evolution model of the gravity field components and an observation model taking the measurement noise into account, the processing and analysis of the measurements acquired during its experimentation in the Mediterranean Sea, then the comparison of the gravimetric signal obtained with the reference data.
6

Testes sobre a eficiência do modelo do geopotencial EGM2008 na cidade de Porto Alegre

Nunes, Vagner Conceição January 2010 (has links)
Este estudo apresenta o teste da eficiência do Earth Global Model 2008 (EGM2008) na geração de um modelo geoidal local, através da compatiblização com a ondulação obtida por posicionamento GPS (Global Positioning System) em 63 Referências de Nível (RN’s) localizadas no município de Porto Alegre, Rio Grande do Sul. O objetivo geral da dissertação foi analisar a exatidão do modelo geoidal gerado a partir dos coeficientes do modelo geopotencial EGM2008 para nivelamento por GPS no município de Porto Alegre e os objetivos específicos foram: a avaliação do modelo na região de Porto Alegre, a comparação das ondulações geoidais do EGM2008 (NEGM2008) com as ondulações geoidais em 63 RN’s (NGPS), o ajustamento da componente sistemática do geoide que é a diferença entre NEGM2008 e NGPS e a geração do modelo geoidal local compatibilizado para Porto Alegre. O método adotado apresenta as seguintes etapas: cálculo das ondulações geoidais nas RN’s; eliminação de erros grosseiros; geração do modelo geoidal através dos dados do EGM2008 com resolução de 7” de arco; cálculo da componente sistemática do geoide; ajustamento da componente sistemática através de transformação por polinômio de 2° grau com seis parâmetros pelo Método dos Mínimos Quadrados (MMQ). Os resultados obtidos foram: os parâmetros que compatibilizam o modelo geoidal global com o local e modelo geoidal local compatibilizado no formato raster, contendo as ondulações geoidais para todo o município. O novo modelo apresentou erro médio de 1,9 cm e desvio padrão de 7,2 cm. Os resultados da dissertação confirmam que é possível reduzir o erro associado ao modelo global através dos procedimentos adotados. Dessa maneira, conclui que o método utilizado reduziu o valor médio da componente sistemática de 15,4 cm para 1,9 cm após o ajustamento. / This study presents the Earth Global Model 2008’s (EGM2008) efficiency test on the conception of a local geoid model. The results were acquired through the undulation compatibility obtained by GPS (Global Positioning System) in 63 Bench Mark (BM) located in Porto Alegre, Rio Grande do Sul state, Brazil. The aim of this research was to analyze the accuracy of the geoid model generated from the geopotential model EGM2008’s coefficients to GPS leveling in Porto Alegre. The specific goals were the evaluation of the model in Porto Alegre region’s, the comparison between the EGM2008 (NEGM2008) geoid undulations and the geoid undulations in 63 BM (NGPS), and the adjustment of geoid’s systematic component, that is the difference between NEGM2008 and NGPS and the local geoid model’s conception to Porto Alegre. The method used presents the following steps: geoid undulation on RN’s’s computation; elimination of gross errors; geoid model’s conception through EGM2008’s data with resolution of 7” of arch; geoid’s systematic component computation; adjustment of the systematic component through transformation of 2nd degree polynomial with six parameters by the method of Least Squares. The results were: the parameters that make the models global and local compatible, and local geoid model compatible in raster format, containing the geoid undulations for the entire municipality. The new model showed 1.9 of mean error and 7.2 cm of standard deviation. Through the procedures adopted, the dissertation results’ confirm that it is possible to reduce the error associated of the the global model. Therefore, the conclusion is that the method used reduced the mean error of the systematic component from 15,4 cm to 1.9 cm, after the adjustment.
7

Testes sobre a eficiência do modelo do geopotencial EGM2008 na cidade de Porto Alegre

Nunes, Vagner Conceição January 2010 (has links)
Este estudo apresenta o teste da eficiência do Earth Global Model 2008 (EGM2008) na geração de um modelo geoidal local, através da compatiblização com a ondulação obtida por posicionamento GPS (Global Positioning System) em 63 Referências de Nível (RN’s) localizadas no município de Porto Alegre, Rio Grande do Sul. O objetivo geral da dissertação foi analisar a exatidão do modelo geoidal gerado a partir dos coeficientes do modelo geopotencial EGM2008 para nivelamento por GPS no município de Porto Alegre e os objetivos específicos foram: a avaliação do modelo na região de Porto Alegre, a comparação das ondulações geoidais do EGM2008 (NEGM2008) com as ondulações geoidais em 63 RN’s (NGPS), o ajustamento da componente sistemática do geoide que é a diferença entre NEGM2008 e NGPS e a geração do modelo geoidal local compatibilizado para Porto Alegre. O método adotado apresenta as seguintes etapas: cálculo das ondulações geoidais nas RN’s; eliminação de erros grosseiros; geração do modelo geoidal através dos dados do EGM2008 com resolução de 7” de arco; cálculo da componente sistemática do geoide; ajustamento da componente sistemática através de transformação por polinômio de 2° grau com seis parâmetros pelo Método dos Mínimos Quadrados (MMQ). Os resultados obtidos foram: os parâmetros que compatibilizam o modelo geoidal global com o local e modelo geoidal local compatibilizado no formato raster, contendo as ondulações geoidais para todo o município. O novo modelo apresentou erro médio de 1,9 cm e desvio padrão de 7,2 cm. Os resultados da dissertação confirmam que é possível reduzir o erro associado ao modelo global através dos procedimentos adotados. Dessa maneira, conclui que o método utilizado reduziu o valor médio da componente sistemática de 15,4 cm para 1,9 cm após o ajustamento. / This study presents the Earth Global Model 2008’s (EGM2008) efficiency test on the conception of a local geoid model. The results were acquired through the undulation compatibility obtained by GPS (Global Positioning System) in 63 Bench Mark (BM) located in Porto Alegre, Rio Grande do Sul state, Brazil. The aim of this research was to analyze the accuracy of the geoid model generated from the geopotential model EGM2008’s coefficients to GPS leveling in Porto Alegre. The specific goals were the evaluation of the model in Porto Alegre region’s, the comparison between the EGM2008 (NEGM2008) geoid undulations and the geoid undulations in 63 BM (NGPS), and the adjustment of geoid’s systematic component, that is the difference between NEGM2008 and NGPS and the local geoid model’s conception to Porto Alegre. The method used presents the following steps: geoid undulation on RN’s’s computation; elimination of gross errors; geoid model’s conception through EGM2008’s data with resolution of 7” of arch; geoid’s systematic component computation; adjustment of the systematic component through transformation of 2nd degree polynomial with six parameters by the method of Least Squares. The results were: the parameters that make the models global and local compatible, and local geoid model compatible in raster format, containing the geoid undulations for the entire municipality. The new model showed 1.9 of mean error and 7.2 cm of standard deviation. Through the procedures adopted, the dissertation results’ confirm that it is possible to reduce the error associated of the the global model. Therefore, the conclusion is that the method used reduced the mean error of the systematic component from 15,4 cm to 1.9 cm, after the adjustment.

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