GPS receivers for georeferencing of spatial variability of soil attributes

A caracterização da variabilidade espacial dos atributos do solo é indispensável para subsidiar práticas agrícolas de maneira sustentável. A utilização da geoestatística para caracterizar a variabilidade espacial desses atributos, como a resistência mecânica do solo à penetração (RP) e a umidade gravimétrica do solo (UG), é, hoje, prática usual na agricultura de precisão. O resultado da análise geoestatística é dependente da densidade amostral e de outros fatores, como o método de georreferencimento utilizado. Desta forma, o presente trabalho teve como objetivo comparar dois métodos de georreferenciamento para a caracterização da variabilidade espacial da RP e da UG, bem como a correlação espacial dessas variáveis. Foi implantada uma malha amostral de 60 pontos, espaçados em 20 m. Para as medições da RP, utilizou-se de penetrógrafo eletrônico e, para a determinação da UG, utilizou-se de trado holandês (profundidade de 0,0-0,1 m). As amostras foram georreferenciadas, utilizando-se do método de Posicionamento por Ponto Simples (PPS), com de (retirar) receptor GPS de navegação, e Posicionamento Relativo Semicinemático, com receptor GPS geodésico L1. Os resultados indicaram que o georreferenciamento realizado pelo PPS não interferiu na caracterização da variabilidade espacial da RP e da UG, assim como na estrutura espacial da relação dos atributos.

Indirect georeferencing of terrestrial laser scanning data using control lines

An indirect method for the georeferencing of 3D point clouds obtained with terrestrial laser scanning (TLS) data using control lines is presented. This technique could be used for rapid data acquisition where resources do not permit the use of expensive navigation sensors or the placement of pre-signalised targets. The most important characteristic is the development of a mathematical model based on the principle that the direction vector of the TLS straight line is coplanar with the plane defined by the origin of the TLS system, one endpoint of a control line and the direction vector of the control line in the ground reference coordinate system. The transformation parameters are estimated by minimising the distance between the control lines and their corresponding TLS straight lines. The proposed method was tested using both simulated and real data, and the advantages of this new approach are compared with conventional surveying methods. © 2013 This article is a U.S. Government work and is in the public domain in the USA.

Influence of distance, geometry and number of control stations on quality of local geodetic networks for the purpose of georeferencing of rural properties

The implementation of local geodetic networks for georeferencing of rural properties has become a requirement after publication of the Georeferencing Technical Standard by INCRA. According to this standard, the maximum distance of baselines to GNSS L1 receivers is of 20 km. Besides the length of the baseline, the geometry and the number of geodetic control stations are other factors to be considered in the implementation of geodetic networks. Thus, this research aimed to examine the influence of baseline lengths higher than the regulated limit of 20 km, the geometry and the number of control stations on quality of local geodetic networks for georeferencing, and also to demonstrate the importance of using specific tests to evaluate the solution of ambiguities and on the quality of the adjustment. The results indicated that the increasing number of control stations has improved the quality of the network, the geometry has not influenced on the quality and the baseline length has influenced on the quality; however, lengths higher than 20 km has not interrupted the implementation, with GPS L1 receiver, of the local geodetic network for the purpose of georeferencing. Also, the use of different statistical tests, both for the evaluation of the resolution of ambiguities and for the adjustment, have enabled greater clearness in analyzing the results, which allow that unsuitable observations may be eliminated.

Signal Transceiver Transit Times and Propagation Delay Corrections for Ranging and Georeferencing Applications

The accuracy of ranging measurements depends critically on the knowledge of time delays undergone by signals when retransmitted by a remote transponder and due to propagation effects. A new method determines these delays for every single pulsed signal transmission. It utilizes four ground-based reference stations, synchronized in time and installed at well-known geodesic coordinates and a repeater in space, carried by a satellite, balloon, aircraft, and so forth. Signal transmitted by one of the reference bases is retransmitted by the transponder, received back by the four bases, producing four ranging measurements which are processed to determine uniquely the time delays undergone in every retransmission process. A minimization function is derived comparing repeater's positions referred to at least two groups of three reference bases, providing the signal transit time at the repeater and propagation delays, providing the correct repeater position. The method is applicable to the transponder platform positioning and navigation, time synchronization of remote clocks, and location of targets. The algorithm has been demonstrated by simulations adopting a practical example with the transponder carried by an aircraft moving over bases on the ground.

Evaluation of aerial remote sensing techniques for vegetation management in power line corridors

The following paper presents an evaluation of airborne sensors for use in vegetation management in powerline corridors. Three integral stages in the management process are addressed including, the detection of trees, relative positioning with respect to the nearest powerline and vegetation height estimation. Image data, including multi-spectral and high resolution, are analyzed along with LiDAR data captured from fixed wing aircraft. Ground truth data is then used to establish the accuracy and reliability of each sensor thus providing a quantitative comparison of sensor options. Tree detection was achieved through crown delineation using a Pulse-Coupled Neural Network (PCNN) and morphologic reconstruction applied to multi-spectral imagery. Through testing it was shown to achieve a detection rate of 96%, while the accuracy in segmenting groups of trees and single trees correctly was shown to be 75%. Relative positioning using LiDAR achieved a RMSE of 1.4m and 2.1m for cross track distance and along track position respectively, while Direct Georeferencing achieved RMSE of 3.1m in both instances. The estimation of pole and tree heights measured with LiDAR had a RMSE of 0.4m and 0.9m respectively, while Stereo Matching achieved 1.5m and 2.9m. Overall a small number of poles were missed with detection rates of 98% and 95% for LiDAR and Stereo Matching.

Imagined Landscapes: Geovisualizing Australian Spatial Narratives

Imagined Landscapes teams geocritical analysis with digital visualization techniques to map and interrogate films, novels, and plays in which space and place figure prominently. Drawing upon A Cultural Atlas of Australia, a database-driven interactive digital map that can be used to identify patterns of representation in Australia’s cultural landscape, the book presents an integrated perspective on the translation of space across narrative forms and pioneers new ways of seeing and understanding landscape. It offers fresh insights on cultural topography and spatial history by examining the technical and conceptual challenges of georeferencing fictional and fictionalized places in narratives. Among the items discussed are Wake in Fright, a novel by Kenneth Cook, adapted iconically to the screen and recently onto the stage; the Australian North as a mythic space; spatial and temporal narrative shifts in retellings of the story of Alexander Pearce, a convict who gained notoriety for resorting to cannibalism after escaping from a remote Tasmanian penal colony; travel narratives and road movies set in Western Australia; and the challenges and spatial politics of mapping spaces for which there are no coordinates.

Estudos de metais pesados e isótopos de Pb nos sedimentos da Baía de Sepetiba baseados em geoquímica e na distribuição pelas possíveis áreas fontes

A Baia de Sepetiba é uma laguna costeira separada do oceano por uma ilha barreira. Localiza-se a 60 km da cidade do Rio de Janeiro, em uma importante região geoeconômica do Brasil. O objetivo deste trabalho foi avaliar a distribuição espacial da contaminação dos metais Cu, Pb, V, Cr, Cd, Co, Ni e Zn nos sedimentos da Baia. O mapa das concentrações elaborado pelo método de lixiviação permitiu caracterizar anomalias ao entorno da foz do Rio Guandu, na área da Coroa Grande, do Porto de Itaguaí, da Ilha do Martins, e anomalias ao longo de faixa com direção NW-SE. Os resultados das concentrações totais indicam contaminação por Zn, Cd, próximo a Ilha da Madeira com Pb e Cr associados e Cu e Zn na Restinga de Marambaia, com Ni, Pb e Cr associados. Os resultados dos isótopos de Pb para as razões de 206Pb/207Pb entre 1,23 e 1,27 representam os resíduos industriais e ocorrem em duas áreas: na parte leste da Restinga e entre as Ilhas de Jaguanum e Itacuruçá. A leste/sudeste destas ilhas foi reportada uma razão ainda mais alta (1.30), ainda não identificável na literatura. As correntes marinhas desempenham a redistribuição dos sedimentos e metais associados na Baia, com transporte de oeste para leste da pluma sedimentar descarregada pelos rios. Os principais causadores da poluição da Baia de Sepetiba são uma pilha de rejeito de Zn abandonada, resíduos industriais e domésticos não tratados de forma eficaz, poluentes atmosféricos de siderúrgicas e veículos, e por ventura resíduos de atividades navais e militares.

From the portolan chart of the mediterranean to the latitude chart of the atlantic

Thesis submitted to the Instituto Superior de Estatística e Gestão de Informação da Universidade Nova de Lisboa in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Information Management – Geographic Information Systems

Inventário e Georreferenciação do mundo funerário rupestre medieval no Centro de Portugal

O presente relatório resultou do estágio efetuado na DGPC, no âmbito da componente não-letiva do Mestrado em Arqueologia. O seu propósito centrou-se no Inventário e Georreferenciação das manifestações funerárias rupestres medievais, enquadradas na região do Centro de Portugal. Este trabalho possibilitou a atualização e introdução de inúmeras ocorrências, respeitantes a sepulturas e necrópoles escavadas na rocha, na base de dados da DGPC – o Endovélico. A concretização deste objetivo assentou essencialmente na consulta de bibliografia especializada, assim como de relatórios técnico-científicos. Ao constar do Endovélico, a informação inserida afigura-se como um contributo para o conhecimento e divulgação deste tipo de património medieval, auxiliando, inevitavelmente, no que concerne à sua salvaguarda e proteção. O processamento e sistematização da vasta informação inventariada e georreferenciada possibilitou o desenvolvimento de uma análise, na perspetiva das sepulturas escavadas na rocha como fenómeno funerário alto-medieval. Esta permitiu a criação de uma imagem, ainda que incompleta, dos tipos de agrupamentos existentes e da relação entre as sepulturas e as zonas envolventes, com lugar numa parte do território de Viseu.

Caracterización de los patrones de uso y apropiación del espacio público en los parques metropolitanos en Bogotá. Caso de Estudio: parque el Tunal 2008 – 2011

Este trabajo de grado se realizó con el propósito de presentar una caracterización de los patrones de uso y apropiación del espacio público urbano, específicamente del parque metropolitano el Tunal en el periodo comprendido entre 2008 y 2011. El documento recopila la perspectiva de diferentes actores involucrados con el parque sobre el funcionamiento del mismo y tuvo como enfoque principal identificar los alcances y las limitaciones del parque como escenario educador y recreativo para los usuarios y su entorno inmediato. Como aportes adicionales el documento se acompaña de la georreferenciación de los procesos urbanos identificados sobre el territorio y algunas recomendaciones aplicables al proceso de gestión del espacio público recreativo para superar las limitaciones y potenciar los alcances en la proyección del espacio público como escenario para la construcción de valores ciudadanos.

Extensión y uso de KML para la anotación, georreferenciación y distribución de recursos de tipo MIME

En el actual contexto de la Web 2.0 y de la futura Web Geográfica o simplemente GeoWeb la información georreferenciada cobra cada día más importancia. Desde hace años distintas técnicas han sido desarrolladas para dar solución al problema de la georreferenciación de recursos de distinta índole. Sin embargo ninguna de estas técnicas está exenta de problemas y restricciones. En este estudio presentamos una nueva aproximación que intenta facilitar la georreferenciación y distribución de recursos de tipos contemplados como Multipurpose Internet Mail Extensions (MIME). El elemento básico para la anotación, georreferenciación y también representación del recurso es el Keyhole Markup Language (KML). Este lenguaje permite la anotación y visualización de elementos, así como su extensión para aumentar su funcionalidad. Esta última propiedad se ha utilizado en nuestra aproximación para crear nuevos elementos que permitan la anotación de cualquier tipo de recurso MIME sobre KML obteniendo así la extensión KML MIMEXT. Esta extensión permite describir y georreferenciar tipos de recursos no habituales en el entorno SIG. La encapsulación del propio recurso junto con sus metadatos (incluyendo la georreferenciación) y otros recursos relacionados se realiza mediante la compresión de todos ellos en un único archivo KMZ facilitando así su distribución y mantenimiento. De forma similar a la interpretación de etiquetas HTML5 como video por los navegadores Web, el uso de la extensión MIMEXT podría ser implementado por visores basados en globos virtuales para visualizar o reproducir nuevos tipos de recursos. Para ejemplificar dicho comportamiento se ha implementado un prototipo de aplicación Java basado en el SDK World Wind Java

Evaluation of positioning error-induced pixel shifts on satellite linear push-broom imagery

Georeferencing is one of the major tasks of satellite-borne remote sensing. Compared to traditional indirect methods, direct georeferencing through a Global Positioning System/inertial navigation system requires fewer and simpler steps to obtain exterior orientation parameters of remotely sensed images. However, the pixel shift caused by geographic positioning error, which is generally derived from boresight angle as well as terrain topography variation, can have a great impact on the precision of georeferencing. The distribution of pixel shifts introduced by the positioning error on a satellite linear push-broom image is quantitatively analyzed. We use the variation of the object space coordinate to simulate different kinds of positioning errors and terrain topography. Then a total differential method was applied to establish a rigorous sensor model in order to mathematically obtain the relationship between pixel shift and positioning error. Finally, two simulation experiments are conducted using the imaging parameters of Chang’ E-1 satellite to evaluate two different kinds of positioning errors. The experimental results have shown that with the experimental parameters, the maximum pixel shift could reach 1.74 pixels. The proposed approach can be extended to a generic application for imaging error modeling in remote sensing with terrain variation.

Geographic Distribution and Population Estimate of Leaf-cutting Ants of the Genus Acromyrmex (Hymenoptera: Formicidae) in Southwestern Bahia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aujstamento de redes GPS em conformidade com as exigências da Lei 10.267/2001

In Brazil, there have been several GPS applications and with the introduction of the Law 10.267/2001 that among other dispositions, deals with georeferencing of the rural parcels. However, most commercial softwares of processing and adjustment of GPS data don't let users to evaluate their results in a reliable way. For example, the constraints are normally used as absolute, which provides results with very optimists precisions. The adoption of additional analyses and the implementation of softwares can reduce these kinds of problems. Thus, a software for adjustment of GPS networks was developed, aiming at assisting the requirements of the Law 10.267/2001 in a reliable way. In this context, in this work it is analyzed the adjustments of GPS networks, by using absolute and relative constraints. In the latter, the adjustments were accomplished considering and not considering the correlations among the coordinate positions.