The advances in aerial mapping using unmanned aerial vehicles (UAVs) are increasingly allowing for the surveying of areas that are difficult or unsafe to access. Considering that the cameras boarded on UAVs are non-photogrammetric sensors, positional accuracy and precision are paramount to ensuring that the final product is geometrically consistent and that its coordinates are precise enough within an acceptable range (which depends on the purpose of each application). With this in mind, this work evaluates the positional accuracy of aerial surveys with UAVs supported by the post- processed kinematic (PPK) technique for the generation of cartographic products in compliance with the Brazilian cartographic accuracy standard PEC-PCD. Furthermore, this study proposes a methodology for inserting virtual control points using coordinates adjusted and inserted into the main point of selected images, using the package of solutions for GNSS RTKLIB processing, to forgo Ground Control Points (GCPs) without loss of quality of the cartographic product. This research used a UAV from DJI (model Mavic 2 Pro), equipped with a dual frequency GNSS receiver, where positional records were synchronized with the camera’s shooting times. To validate the technique, 20 checkpoints with known coordinates were selected, and these points were used in statistical tests to assess the accuracy and precision of the survey. The orthomosaic and the digital elevation model were used as the reference for positional coordinates to be compared against the PEC-PCD standards. The results show that the discrepancy is, on average, 0.126 m for planimetric coordinates and 0.066 m for altimetry. No outliers were found, suggesting a Gaussian sampling distribution. The application of Student’s t- test indicated the existence of a small bias, suggesting the displacement of coordinates along the three axes. The chi-square test showed results below the tabulated limits, attesting to the high precision of the survey. Finally, the root mean squared error (RMSE) was lower than the standard error limit for PEC-PCD class A planialtimetric cartographic products on a 1:1,000 scale. The viability of this technique is thus confirmed.
Há pouco mais de uma década os resíduos sólidos domiciliares de Rio Grande, município localizado no sul da Planície Costeira do Rio Grande do Sul, passaram a ser depositados em um aterro sanitário. Este trabalho reúne dados de caracterização geológica, geomorfológica e pedológica do local do aterro e resultados de pesquisas geotécnicas sobre a impermeabilização de fundo do aterro sanitário com adição de bentonita ao solo compactado. Estas pesquisas foram realizadas com dois solos locais, um superficial e outro subsuperficial, e duas jazidas. Para estes ensaios foram variados teores de bentonita e energia de compactação. Em síntese, o solo MBAR foi o único que na condição natural apresentou valores de condutividade hidráulica abaixo do permitido para uso como liner, o solo natural requer um teor de bentonita de 14% e solo ARMAR requer entre 4 e 6% de bentonita, dependendo da metodologia adotada. Esta nova solução constitui opção para o próprio empreendimento em futuras intervenções ou para outras obras de similar escopo, num mesmo contexto geológico-geotécnico. Quanto à sorção de íons, misturas de solo ARMAR e bentonita apresentaram resultados aceitos pela legislação vigente. Resultados de ensaios de cisalhamento direto evidenciaram a significativa redução no ângulo de atrito efetivo e uma anisotropia importante das misturas de solo-bentonita, o que são indícios de que a análise do comportamento mecânico destas misturas deva ser detalhadamente realizada antes do seu uso.
A alfabetização cartográfica é fundamental para o ensino de Geografia, uma vez que, para ler o espaço, o estudante necessita interpretar mapas, imagens e outras representações geográficas. Nos últimos anos, foram desenvolvidos muitos materiais didáticos envolvendo atividades lúdicas que despertam a curiosidade e o interesse dos alunos. Pensando na Cartografia Escolar, os Atlas Eletrônicos surgem com uma abordagem inovadora e maior interação entre os conteúdos trabalhados e a realidade local. O aluno é instigado a realizar uma análise crítica do seu espaço vivido, ora construindo-o, ora desconstruindo-o, através da observação dos elementos socioambientais, fazendo com que no aluno seja despertado maior interesse pelo estudo do espaço geográfico. Nesta perspectiva, teve-se o objetivo de abordar a importância do estudo do espaço local na perspectiva da cartografia escolar a partir da elaboração de um Atlas Eletrônico e Socioeconômico. Para isso, realizou-se um estudo de caso no município de Restinga Sêca, RS. Metodologicamente, considerou-se como unidade de análise espacial o município constituído por seus setores censitários. O Atlas possui uma interação parcial com o usuário, possibilitando a manipulação de um conjunto de mapas com temas predefinidos, e é composto por recursos de multimídia, com textos, imagens e animações. Desta forma, verificou-se maior interatividade no ensino da Geografia, articulando o conteúdo proposto com o espaço vivido pelo aluno. Palavras-chave Cartografia Escolar, Atlas Eletrônico, Ensino de Geografia Municipal electronic atlas as a didactic alternative for school cartography Abstract Cartographic literacy is fundamental for the teaching of geography, since to read the space the student needs to interpret maps, images and other geographical representations. In recent years, many teaching materials have been developed involving recreational activities that arouse students' curiosity and interest. Thinking about School Cartography, Electronic Atlas come up with an innovative approach and greater interaction between the contents worked and the local reality. The student is encouraged to perform a critical analysis of his lived space, sometimes building it, sometimes deconstructing it through the observation of socioenvironmental elements, making the student arouse greater interest in the study of geographical space. In this perspective, the objective was to address the importance of studying the local space in the perspective of school cartography from the elaboration of an Electronic and Socioeconomic Atlas, for which a case study was carried out in the municipality of Restinga Sêca, RS. Methodologically, the municipality constituted by its census sectors was considered as a unit of spatial analysis. The Atlas has a partial interaction with the user, allowing the manipulation of a set of maps with predefined themes, and is supported by multimedia resources with texts, images and animations. Thus, there was greater interactivity in the teaching of Geography, articulating the proposed content with the space experienced by the student. Keywords School Cartography, Electronic Atlas, Geography teaching
The occurrence of disasters in Brazil by natural processes has been increasing along the years. One of these phenomena is mass movements, a destructive phenomenon which may cause damage to socioeconomic. The morphometric variables are becoming useful in geomorphologic analysis, mainly in diagnosis of susceptible areas to those processes. This way, the objective of this work is to identify susceptible areas of mass movements in the interface between meridional plateau and the central depression in Vale do Taquari region, using geomorphometric variable at a scale of 1:250.000. This morphometric analysis contains Remote Sensing and geoprocessing, so it becomes an effective and low cost method. GIS software (Geographic Information System) was used to maps algebra from the statistical methods AHP (Analytical Hierarchy Process) and Delphi, in which pondering and the hierarchy of influential variables in this analysis. The final product is an analysis map of susceptibility to mass movements in the mentioned region. In the map it is observed that the region has a high degree of susceptibility in most aspects. With this data it is possible to carry out a proper planning and management of the territory, providing more safety to the occupation of those areas.
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