No decorrer dos últimos anos têm ocorrido um significativo aumento de aplicações com Aeronaves Remotamente Pilotadas (RPAs) na área da Cartografia, o que torna necessário o conhecimento da qualidade ...obtida em tais aplicações. Diante disso, instituições de diversos países têm desenvolvido normas com a finalidade de avaliar a qualidade dos produtos geoespaciais. Além disso, desenvolveram também outras normas com a finalidade de englobar padrões de acurácia de posicionamento para ortoimagens digitais. Neste sentido, o objetivo deste artigo foi comparar três normas que abordam o controle de qualidade posicional aplicáveis à RPA: (i) ET-CQDG (Decreto n° 89.817); (ii) a norma de Execução do INCRA n° 2 de 2018 e; (iii) a norma da ASP RS. No experimento prático, realizou-se o processo de avaliação da acurácia posicional de uma ortofoto obtida por RPA na região de Janaúba-MG. A ortofoto foi classificada na classe A para a escala de 1:1000 para a norma ET-CQDG. Já para a ASPRS ao nível de confiança de 95% o produto apresentou uma acurácia posicional de 0,428 metros e, de acordo com a norma do INCRA, os pontos obtidos por RPA podem ser utilizados para o georreferenciamento considerando todos tipos de limites. Através dos resultados obtidos, foi possível inferir que as normas necessitam de uma melhoria em suas metodologias, para que todo esse processo seja feito de forma clara e objetiva para o produtor e o usuário.
Los participantes en el proyecto de asistencia técnica del IPGH (PAT2018) (Agenda del IPGH 2010-2020) "Propuesta de adopción de metodologías y procedimientos para la evaluación de la calidad de la ...información geográfica para los Estados miembros del IPGH", decidieron abordar la realización de una propuesta de guía genérica para la evaluación de la exactitud posicional de datos espaciales. En la elaboración de la propuesta de guía se han aplicado el ciclo de Deming y un método específico de desarrollo de guías basadas en evidencias. Se ha asumido su alineación con las normas internacionales de la familia ISO 19100 y con los métodos de evaluación de la exactitud posicional más extendidos en Hispanoamérica. Igualmente, se presentan los distintos alcances asumidos para su elaboración, tanto en lo que se refiere a contenidos como a la perspectiva genérica desarrollada.
Este trabalho destaca a importância da utilização de técnicas simples de estatística espacial no controle de qualidade posicional em dados espaciais. Para tanto, são apresentados métodos de análise ...do padrão de distribuição espacial de dados pontuais, bem como a análise de tendências na amostra de discrepâncias posicionais. Para avaliar a distribuição espacial de pontos, utilizaram-se os métodos do Vizinho Mais Próximo e da Função K de Ripley. Já para análise de tendência, utilizou-se a média direcional dos vetores de discrepâncias aliada à variância circular. Neste sentido, propõe-se uma metodologia para o controle de qualidade posicional em dados espaciais abrangendo desde o planejamento da amostra e avaliação de seu padrão de distribuição espacial, a aplicação de teste de tendências analisando a normalidade dos dados, e a classificação em relação a uma determinada norma de acurácia posicional. Para o experimento prático, avaliou-se uma ortoimagem gerada a partir de uma cena do sensor PRISM do satélite ALOS. Os resultados mostram que a ortoimagem é acurada para a escala de 1:25.000, sendo classificada como classe A conforme padrão brasileiro de acurácia posicional, não apresentando tendências nas coordenadas. Como principal contribuição deste trabalho, tem-se a incorporação de técnicas de estatística espacial no controle de qualidade cartográfica.
Remote sensing methodologies could contribute to a more sustainable agriculture, such as monitoring soil preparation for cultivation, which should be done properly, according to the topographic ...characteristics and the crop’s nature. The objectives of this work are to (1) demonstrate the potential of unmanned aerial vehicle (UAV) technology in the acquisition of 3D data before and after soil tillage, for the quantification of mobilised soil volume; (2) propose a methodology that enables the co-registration of multi-temporal DTMs that were obtained from UAV surveys; and (3) show the relevance of quality control and positional accuracy assessment in processing and results. An unchanged-area-matching method based on multiple linear regression analysis was implemented to reduce the deviation between the Digital Terrain Models (DTMs) to calculate a more reliable mobilised soil volume. The production of DTMs followed the usual photogrammetric-based Structure from Motion (SfM) workflow; the extraction of fill and cut areas was made through raster spatial modelling and statistical tools to support the analysis. Results highlight that the quality of the differential DTM should be ensured for a reliable estimation of areas and mobilised soil volume. This study is a contribution to the use of multi-temporal DTMs produced from different UAV surveys. Furthermore, it demonstrates the potential of UAV data in the understanding of soil variability within precision agriculture.
The quality of CNC machines and their control systems is assessed in terms of the contour accuracy, consisting of two components: the accuracy in sending the signal confirming that the working ...component has reached the specified coordinate; and the accuracy in executing the stop command, given the inertia of the actuators. Recommendations are made regarding the selection of the device for monitoring the motion of the working components in a CNC machine with a gapless gear transmission and a torsional motor. If the required positional accuracy is low, it is acceptable to disregard the error in the gear ratio of the mechanical transmission between the sensor and the guide screw (or any other device converting rotation into linear motion). When using a device for monitoring the motion of the working components in a CNC machine, the adjustment of the sensor at the center of the scale interval should be as precise as possible.
The horizontal accuracy of historical Google Earth (GE) images at four epochs between the years 2000 and 2018, and the vertical accuracy of its elevation data within Lagos State, in Nigeria, are ...respectively evaluated by comparison with a very high–resolution digital orthomosaic and comparison with 558 ground control points. Two readily available 30-m digital elevation models (DEMs) — the Shuttle Radar Topography Mission (SRTM) v3.0 and the Advanced Land Observing Satellite World 3D (AW3D) DEM v2.1. — were also compared with GE elevations. A novel approach for assessing the space–time variations in the magnitude and direction of errors in GE imagery is presented. For horizontal accuracy, the root mean square errors (RMSEs) are as follows — year 2000 (16.9 m), year 2008 (16.4 m), year 2012 (6.1 m) and year 2018 (6.1 m). The most recent GE imagery (year 2018) had the least horizontal error while year 2000 had the largest horizontal error. The horizontal shift was skewed towards the western and north-western directions, indicative of systematic error. In terms of the vertical accuracy, GE elevation data had the lowest accuracy and highest RMSE of 6.21 m followed by AW3D with an RMSE of 4.39 m and SRTM with an RMSE of 3.68 m.
Wire-driven continuum surgical robots are attracting significant interest in minimally invasive surgeries owing to their high dexterity level and miniaturization. However, twist deformation due to ...the external force at the end effector decreases the accuracy and controllability of these robots. In this study, we analyze the two factors responsible for twist deformation and propose models incorporating these factors. In our analyses, we first consider twist deformation due to the elastic deformation of the wire; when a tensioned wire is subjected to normal force, a sag effect occurs, which results in twist deformation in the robot. We analyze this sag effect statically considering the material properties of the wire. We also analyze the twist deformation due to the clearance between the wire and hole boundary in the spacer of the robot. Clearance is required in a wire-driven continuum robot to realize bending motion; however, this is considered one of the main causes of twist deformation and is referred to as the clearance effect. Subsequently, we propose sag and clearance effect models that quantitatively predict the twist deformation. The results of the experiments conducted to verify the accuracy of the proposed models, including a payload test using a conventional continuum robot comprising spherical joints, indicate that the accuracy of the proposed models is 95%.
The most accurate LLR (lunar laser ranging) initiative, named APOLLO (apache point observatory lunar laser-ranging operation) demonstrated millimeter-range positional accuracy in 2009, thus improving ...LLR by one order-of-magnitude.
Since, LLR is a foundational technique in studying gravity, Murphy (principal investigator of APOLLO) stated in 2009, that with this millimeter-range accuracy, the simulation model has been found to be the limiting-factor in extracting the theoretical science results, and hence, we should:
(1) develop the science case and expand our ability to model LLR for a new regime of high precision, (2) develop the theoretical tools for honing the science case for submillimeter LLR, and (3) explore which model/code is worth putting our efforts into. (4) Since millimeter-quality
data are a recent development, the model effort lags. (5) Finally, we will code-in new physics so that we may simulate sensitivities. In connection with simulation model/code, Murphy stated in 2013, that among the four available LLR simulation models: JPL (jet propulsion
laboratory), CfA (the Harvard-Smithsonian center for astrophysics), LU (leibniz University, Hannover, Germany), and IMCCE (Institut de Mecanique celeste et de calcul des Ephemerides, France), the JPL model currently
produces weighted RMS (root-mean-square) residuals at ∼18 mm, which is about half of the other models; so, clearly a gap exists from millimeter ranging-precision of APOLLO. Hence, the CfA, LU, and IMCCE are engaged, since 2013, in a stepwise comparative streamlining effort to identify
the model-differences, errors, and shortcomings. All the four available LLR simulation models can be classified as GR (general relativity)-astronomers model; they are basically similar. Professor Douglas Currie of the University of Maryland, College Park, NASA Lunar Science Institute, stated
in a Conference presentation, in 2012, that Ground stations, that is, the lunar observatories, have improved by a factor of 200, but the agreement between observations and fitted theory has plateaued at ∼2 cm over the past two decades. However, no substantial progress on improving
the fit has been reported in the published literature, till date. Based on about a quarter-century of experience in doing high-precision numerical simulation of celestial orbits, the authors have developed LESMA (lunar Ephemeris at sub Microarcsecond accuracy)
utilizing the methodology of evolved general relativity (EGR) that has incorporated the following two concepts: (1) Relativistic time for integration and (2) methodology of conservation of magnitude of the angular momentum, MΦ , for Φ-rotation
(in addition to the θ-rotation that leads to the rosetting ellipse) of the orbital plane. Incorporation of the two above-mentioned concepts has led to three orders-of-magnitude accuracy-improvement of the computed (1) precession (compared to JPL's DE405) of Lunar orbit,
as verified using three independent methods and (2) radial position (compared to JPL's DE430/431) of the Moon. LESMA will enable scientists to make efficient use of research-funds from NASA, etc., for production of new science results from APOLLO. LESMA will also be useful for getting
better science results (than Folkner reported {in 2014} submeter accurate Position of the Moon) from the GRAIL (gravity recovery and Interior laboratory) mission (costing 500 million USD), by spending a little more for revisiting the computations, utilizing
LESMA data.
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