scholarly journals ANÁLISIS COMPARATIVO DE SOFTWARE PARA OBTENER MDT CON FOTOGRAMETRÍA RPAS

Author(s):  
Alba N. Arévalo-Verjel ◽  
José Luis Lerma ◽  
José Fernández

Los RPAS (Sistemas de aeronaves pilotados a distancia) son muy utilizados en fotogrametría para la toma de imágenespor su alta resolución espacial y rapidez de respuesta, pudiendo llegar a zonas de difícil acceso, siendo importante diseñarun buen procedimiento en campo para minimizar los errores en la toma de datos. Se recomienda utilizar puntos de apoyo(PA) terrestres utilizando RPAS convencional, que no trabajan con sistemas RTK (Real Time Kinematic). Asimismo,existen en el mercado programas fotogramétricos libres y licenciados para generar modelos digitales de superficie (MDS),del terreno (MDT) y ortofotomosáicos. En este artículo se utilizan dos programas fotogramétricos para procesar imágenescapturadas con RPAS como son Agisoft Metashape y Recap Photo, utilizando puntos de apoyo y control terrestre. Elestudio se llevó a cabo en Almenara (España) donde se hizo el levantamiento topográfico con RPAS, capturándose 100imágenes digitales, en un área de 0.38 km2. Se utilizaron 6 PA con la finalidad de orientar bien las imágenes digitales enel sistema de coordenadas local y realizar de forma adecuada la georreferenciación de las imágenes obtenidas duranteel vuelo. Para la obtención del MDT se utilizó el software CloudCompare para hacer el filtrado en la nube de puntosobtenidas de ambos softwares. Los resultados muestran una diferencia en altura entre los dos MDT menor a 28 cmtomando como referencia el MDT de la nube de puntos de Agisoft metashape y en cuanto al error en los puntos apoyoRecap Photo presento mayor error.

2021 ◽  
Vol 53 ◽  
pp. 705-715
Author(s):  
Mitchell R. Woodside ◽  
Joseph Fischer ◽  
Patrick Bazzoli ◽  
Douglas A. Bristow ◽  
Robert G. Landers

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 657
Author(s):  
Aoki Takanose ◽  
Yoshiki Atsumi ◽  
Kanamu Takikawa ◽  
Junichi Meguro

Autonomous driving support systems and self-driving cars require the determination of reliable vehicle positions with high accuracy. The real time kinematic (RTK) algorithm with global navigation satellite system (GNSS) is generally employed to obtain highly accurate position information. Because RTK can estimate the fix solution, which is a centimeter-level positioning solution, it is also used as an indicator of the position reliability. However, in urban areas, the degradation of the GNSS signal environment poses a challenge. Multipath noise caused by surrounding tall buildings degrades the positioning accuracy. This leads to large errors in the fix solution, which is used as a measure of reliability. We propose a novel position reliability estimation method by considering two factors; one is that GNSS errors are more likely to occur in the height than in the plane direction; the other is that the height variation of the actual vehicle travel path is small compared to the amount of movement in the horizontal directions. Based on these considerations, we proposed a method to detect a reliable fix solution by estimating the height variation during driving. To verify the effectiveness of the proposed method, an evaluation test was conducted in an urban area of Tokyo. According to the evaluation test, a reliability judgment rate of 99% was achieved in an urban environment, and a plane accuracy of less than 0.3 m in RMS was achieved. The results indicate that the accuracy of the proposed method is higher than that of the conventional fix solution, demonstratingits effectiveness.


2021 ◽  
Vol 3 (2) ◽  
pp. 363-382
Author(s):  
Md. Kamrul Hasan ◽  
Takashi S. T. Tanaka ◽  
Md. Rostom Ali ◽  
Chayan Kumer Saha ◽  
Md. Monjurul Alam

To reduce human drudgery and the risk of labor shortages in the Asian developing countries, the appropriate introduction of agricultural machinery, especially combine harvesters, is an urgent task. Custom hiring services (CHSs) are expected to contribute to making paddy harvesters prevalent in developing countries; however, the economic performance has been rarely quantified. The study was carried out to precisely evaluate the machine performance attributes of medium and large combine harvesters using the real-time kinematic (RTK) global navigation satellite system (GNSS) and to estimate the economic performance of CHSs of paddy harvesters in Japan, as a typical case of Asian countries. The financial profitability was evaluated by four major indicators: net present value, benefit–cost ratio, internal rate of return, and payback period. The financial indicators showed that both types of harvester could be considered financially viable. Thus, the investment in combine harvesters can be highly profitable for CHS business by a local service provider and custom-hire entrepreneur, providing a great opportunity to use a combine harvester without initial investment by general farmers. The findings demonstrated the high feasibility of CHSs of paddy harvesters in Japan, while they highlighted that further study is needed to estimate the feasibility of CHS in the other Asian developing countries.


2021 ◽  
Vol 13 (4) ◽  
pp. 823
Author(s):  
Lin Zhao ◽  
Jiachang Jiang ◽  
Liang Li ◽  
Chun Jia ◽  
Jianhua Cheng

Since the traditional real-time kinematic positioning method is limited by the reduced satellite visibility from the deprived navigational environments, we, therefore, propose an improved RTK method with multiple rover receivers sharing a common clock. The proposed method can enhance observational redundancy by blending the observations from each rover receiver together so that the model strength will be improved. Integer ambiguity resolution of the proposed method is challenged in the presence of several inter-receiver biases (IRB). The IRB including inter-receiver code bias (IRCB) and inter-receiver phase bias (IRPB) is calibrated by the pre-estimation method because of their temporal stability. Multiple BeiDou Navigation Satellite System (BDS) dual-frequency datasets are collected to test the proposed method. The experimental results have shown that the IRCB and IRPB under the common clock mode are sufficiently stable for the ambiguity resolution. Compared with the traditional method, the ambiguity resolution success rate and positioning accuracy of the proposed method can be improved by 19.5% and 46.4% in the restricted satellite visibility environments.


2021 ◽  
Vol 14 (2) ◽  
pp. 105
Author(s):  
Maelckson Bruno Barros Gomes ◽  
André Luis Silva Santos

<p class="04CorpodoTexto">Este artigo tem por objetivo aplicar geotecnologias para obtenção de informações planialtimétricas a fim de avaliar a viabilidade de implantação do campus Centro Histórico/Itaqui-Bacanga do IFMA. Considerando que para realização de levantamento por métodos tradicionais é recomendado que seja realizado o destocamento e a limpeza do terreno previamente, avaliou-se a realização do levantamento planialtimétrico a partir de um par de receptores <em>Global Navigation Satellite System</em> (GNSS) pelo método <em>Real Time Kinematic</em> (RTK) pós processado e também a partir da realização de levantamento fotogramétrico, utilizando aeronave remotamente pilotada (ARP), popularmente conhecida como drone. Esta análise permitiu demonstrar que o aerolevantamento com a ARP pode ser aplicado na concepção inicial de um projeto de engenharia, conforme classificação do Tribunal de Contas da União (TCU) para níveis de precisão, pois obteve-se uma diferença orçamentária de 19% entre os projetos elaborados a partir das duas geotecnologias.</p><div> </div>


2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Tamer Baybura ◽  
İbrahim Tiryakioğlu ◽  
Mehmet Ali Uğur ◽  
Halil İbrahim Solak ◽  
Şeyma Şafak

Real-time kinematic (RTK) technique is important for mapping applications requiring short measure time, the distance between rover and base station, and high accuracy. There are several RTK methods used today such as the traditional RTK, long base RTK (LBRTK), network RTK (NRTK), and precise point positioning RTK (PPP-RTK). NRTK and LBRTK are popular with the advantage of the distance, the time, and accuracy. In the present study, the NRTK and LBRTK measurements were compared in terms of accuracy and distance in a test network with 6 sites that was established between 5 and 60 km. Repetitive NRTK and LBRTK measurements were performed on 6 different days in 2015-2017-2018 and additionally 4 campaigns of repetitive static measurements were carried out in this test network. The results of NRTK and LBRTK methods were examined and compared with all relevant aspects by considering the results of the static measurements as real coordinates. The study results showed that the LBRTK and NRTK methods yielded similar results at base lengths up to 40 km with the differences less than 3 cm horizontally and 4 cm vertically.


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