Estimating invasive grasses heights with images from a remotely piloted aircraft in Brazilian Cerrado: accuracy of Global Navigation Satellite System from Phantom 4

The purpose of this study was to estimate the height of invasive plants from UAV images using the GNSS integrated into the UAV and to evaluate the accuracy of the GNSS. DSM and DTM elevation models were produced from images collected by remotely piloted aircraft (RPA). The production of CHIS occurred through the subtraction of the DSM and the DTM. In order to assess the accuracy of the CHIS+GNSS model, the CHIS+RTK model was generated as the observed variable. The comparison between the models took place in two sample areas represented by typical vegetation of Cerrado and Brachiaria grass. The statistical tests adopted were: Spearman correlation, RMSE, MAE and Wilcoxon test. The visual interpretation of the selected images showed that the CHIS+GNSS model presented errors in the identification of the ground cover represented by invasive grasses when compared to the CHIS+RTK model, being less accurate in the classification of the canopy heights of the invasive species. Statistical tests indicated that the CHIS+GNSS model showed significant differences in the identification of invasive species, with greater height error (0.24 cm) in the sample area. From these results it can be seen that the CHIS+RTK model is more assertive in detecting ground cover composed by exotic grasses than the CHIS+GNSS model.

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Modelo Digital do Terreno obtido por RPA para cálculo de volume de terra em morros

The Journal of Engineering and Exact Sciences ◽

10.18540/jcecvl7iss1pp12035-01-09e ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Leonardo Carlos Barbosa ◽

Laízy de Santana Azevedo ◽

José Rubens Scatimburgo Silva ◽

Willian dos Santos Ferreira ◽

Tarciso Binoti Simas

Keyword(s):

Global Navigation Satellite System ◽

Satellite System ◽

Navigation Satellite ◽

Remotely Piloted Aircraft ◽

Global Navigation ◽

Global Navigation Satellite

O uso de RPAs (Remotely Piloted Aircraft) popularmente conhecidas como Drones, tem se destacado como uma das técnicas com amplo potencial de contribuição em diversos campos científicos. A possibilidade de geração de produtos cartográficos e Modelos Digitais do Terreno de maneira rápida em comparação com as técnicas de topografia tradicionais como estação total vem se mostrando bastante aplicável no diagnóstico e na prevenção de acidentes de ordem geológico-geotécnica. Este artigo avaliou a acurácia do cálculo de volume, realizado por meio de Modelos Digitais de Terreno (MDTs), gerados a partir das tecnologias RPAs, LiDAR (Light Detecting And Ranging) e GNSS (Global Navigation Satellite System) na localidade do Alto da Sé em Olinda. Os resultados foram classificados de acordo com o PEC(Padrão de Exatidão Cartográfica) obtendo erro planimétrico inferior a 0,5mm, obtendo a classificação A em escala de 1/2000. O levantamento com RPA apresentou melhor acurácia no cálculo do volume.

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On quality of NKG2015 geoid model over the Nordic countries

Journal of Geodetic Science ◽

10.1515/jogs-2019-0010 ◽

2019 ◽

Vol 9 (1) ◽

pp. 97-110

Author(s):

Mehdi Eshagh ◽

Jenny Berntsson

Keyword(s):

Confidence Interval ◽

Ocean Circulation ◽

Statistical Tests ◽

Satellite System ◽

Average Error ◽

Variance Estimator ◽

Geoid Model ◽

Local Variance ◽

Baltic Countries ◽

Global Navigation Satellite

Abstract The NKG2015 geoid model covers the Nordic and Baltic countries and has been computed based on the least-squares modification of Stokes’ formula with additive corrections method. New and precise terrestrial, airborne and shipborne gravimetric measurements, the recent global gravity model of the gravity field and steady-state ocean circulation explorer (GOCE) and detailed digital terrain models over each territory have been used for computing this new geoid model. Some estimates for the error of this model have been roughly presented by comparing it with the global navigation satellite system (GNSS) data over each country. In this paper, our goal is to have a closer look at the relative error of this model by performing some statistical tests and finding the proper corrective surface for absorbing the systematic errors over each country. Our main assumption is realisticity of the errors of GNSS/levelling data and we will investigate its consequences in estimating the error of the geoid model. Our results show that the 4-parameter corrective surface is suitable for modelling the systematic trends of the differences between the gravimetric and GNSS geoid heights in Sweden, Denmark and Finland, but a filtered discrepancies by a confidence interval of 95% should be used for Sweden. A 7-aparameter model is suitable for the filtered discrepancies with the confidence interval of 95% in Norway. Based on the selected corrective surface and our newly developed regional iterative variance estimator, the confidence interval for the error of NKG2015 geoid model in Sweden, Denmark and Norway yielded 0-6.5 mm, 1.8-5.2 mm, 14.8-17.7 mm, respectively with a confidence level of 95%. We could not estimate the geoid error in Finland because the given error of the GNSS/levelling heights is significantly larger than the size of residuals. Based on the selected corrective surfaces and our presented local variance estimator, the average error of geoid becomes 3.6, 2.4, 8.8 and 5.8 mm with a confidence interval of 68%, respectively, over Sweden, Denmark, Norway and Finland.

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Pengaruh Self Help Group Terhadap Tingkat Harga Diri Keluarga Dengan Penderita Skizofrenia Di Poli Jiwa Puskesmas Kalitidu

Jurnal Ilmu Kesehatan MAKIA ◽

10.37413/jmakia.v10i2.106 ◽

2020 ◽

Vol 10 (2) ◽

Author(s):

Errix Kristian Julianto ◽

Yusuf Efendi

Keyword(s):

Mental Health ◽

Statistical Tests ◽

Self Esteem ◽

The Self ◽

Wilcoxon Test ◽

Health Clinic ◽

Mental Health Clinic ◽

Self Help ◽

Post Test ◽

Self Help Group

ABSTRAKSelf Help Group merupakan kelompok-kelompok termasuk orang dengan ikatan bersama yang secara sukarela datang bersama-sama untuk berbagi, menjangkau dan belajar satu sama lain dalam lingkungan yang terpercaya, mendukung dan terbuka (Knight, 2014). Tujuan penelitian ini adalah Menganalisis pengaruh Pengaruh Self Help Group Terhadap Tingkat Harga Diri Keluarga Dengan Penderita Skizofrenia Di Poli Jiwa Puskesmas KalitiduDesain penelitian ii menggunakan Pre eksperiment dengan pendekatan one group pre-posttest design. Populasi pada penelitian ini adalah Seluruh keluarga penderita Skizofrenia di PKU Jiwa Kalitidu yang berjumlah 32 dengan teknik total sampling diperoleh 32 responden. Instrumen yang digunakan adalah kuesioner Harga diri. Kemudian penelitian ini dianalisa menggunakan wilcoxon sign rank.Dari hasil penelitian menunjukkan bahwa lebih dari sebagian responden mempunyai tingkat harga diri rendah yaitu terdapat 18 (56,2%) responden sebelum di beri self help group sedangkan setelah diberikan Self Help group menunjukkan bahwa sebagian besar responden mempunyai harga diri tinggi yaitu terdapat 25 (78,1%) responden. Berdasarkan uji statistik dengan menggunakan SPSS uji Wilcoxon Signed Ranks antara nilai pre test dan post test menunjukkan bahwa kondisi responden sebelum dan setelah dilakukan intervensi dengan self help group pada harga diri dengan nilai uji wilcoxon sebesar 0, 001 dengan nilai kesalahan sebesar 0,05.Berdasarkan hasil penelitian dapat disimpulkan ada pengaruh dari Self Help Group terhadap harga diri keluarga dengan penderita depresi di poli jiwa puskesmas kalitidu Bojonegoro. Diharapkan para keluarga dengan penderita depresi di poli jiwa puskesmas kalitidu bojonegoro tetap aktif dalam mengikuti kegiatan Self Help Group di poli jiwa puskesmas kalitidu bojonegoro sehingga keluarga mampu meningkatkan harga diri. Kata Kunci : Self Help Group, Harga diri, Skizofrenia ABSTRACTSelf Help Groups are groups including people with common ties who voluntarily come together to share, reach out and learn from each other in a trusted, supportive and open environment (Knight, 2014). The purpose of this study was to Analyze the effect of Self Help Group Influence on the Self-Esteem Level of Family with Schizophrenia Patients in Psychiatric Poly at Puskesmas Kalitidu. This research design uses Pre experiment with one group pre-posttest design approach. The population in this study were all families of Schizophrenics in PKU Kalitidu Mental, amounting to 32 with a total sampling technique obtained by 32 respondents. The instrument used was the self-esteem questionnaire. Then this study was analyzed using Wilcoxon sign rank.From the results of the study showed that more than a few respondents had low levels of self-esteem, there were 18 (56.2%) respondents before being given a self-help group while after being given a Self-Help group showed that most respondents had high self-esteem ie there were 25 (78 , 1%) of respondents. Based on statistical tests using the SPSS Wilcoxon Signed Ranks test between the pre test and post test values indicate that the condition of respondents before and after intervention with self help groups on self-esteem with Wilcoxon test values of 0, 001 with an error value of 0.05. Based on the results of the study it can be concluded that there is an effect of the Self Help Group on the self-esteem of families with depressed patients at the mental health clinic of Bojonegoro kalitidu. It is expected that families with depression sufferers at the Kalitidu Bojonegoro mental health clinic remain active in participating in the Self Help Group activities in the mental health clinic at Kalitidu Bojonegoro so that families are able to increase self-esteem.Keywords : Self Help Group, Self-Esteem, Schizophreni

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The characteristics of transforming coordinates from the geocentric system WGS-84 for the Mercator projection under low latitudes conditions

Geodesy and Cartography ◽

10.22389/0016-7126-2018-940-10-2-6 ◽

2018 ◽

Vol 940 (10) ◽

pp. 2-6

Author(s):

J.A. Younes ◽

M.G. Mustafin

Keyword(s):

Coordinate System ◽

Satellite System ◽

Programming Algorithm ◽

Low Latitude ◽

Model Calculations ◽

Mercator Projection ◽

Low Latitudes ◽

Rectangular Coordinates ◽

Global Navigation Satellite ◽

Coordination Methods

The issue of calculating the plane rectangular coordinates using the data obtained by the satellite observations during the creation of the geodetic networks is discussed in the article. The peculiarity of these works is in conversion of the coordinates into the Mercator projection, while the plane coordinate system on the base of Gauss-Kruger projection is used in Russia. When using the technology of global navigation satellite system, this task is relevant for any point (area) of the Earth due to a fundamentally different approach in determining the coordinates. The fact is that satellite determinations are much more precise than the ground coordination methods (triangulation and others). In addition, the conversion to the zonal coordinate system is associated with errors; the value at present can prove to be completely critical. The expediency of using the Mercator projection in the topographic and geodetic works production at low latitudes is shown numerically on the basis of model calculations. To convert the coordinates from the geocentric system with the Mercator projection, a programming algorithm which is widely used in Russia was chosen. For its application under low-latitude conditions, the modification of known formulas to be used in Saudi Arabia is implemented.

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Detecting Apples in the Wild: Potential for Harvest Quantity Estimation

Sustainability ◽

10.3390/su13148054 ◽

2021 ◽

Vol 13 (14) ◽

pp. 8054

Author(s):

Artur Janowski ◽

Rafał Kaźmierczak ◽

Cezary Kowalczyk ◽

Jakub Szulwic

Keyword(s):

Image Analysis ◽

Pilot Study ◽

Production Management ◽

Satellite System ◽

Morphological Operations ◽

Computational Performance ◽

Analysis Methods ◽

Manual Counting ◽

In The Wild ◽

Global Navigation Satellite

Knowing the exact number of fruits and trees helps farmers to make better decisions in their orchard production management. The current practice of crop estimation practice often involves manual counting of fruits (before harvesting), which is an extremely time-consuming and costly process. Additionally, this is not practicable for large orchards. Thanks to the changes that have taken place in recent years in the field of image analysis methods and computational performance, it is possible to create solutions for automatic fruit counting based on registered digital images. The pilot study aims to confirm the state of knowledge in the use of three methods (You Only Look Once—YOLO, Viola–Jones—a method based on the synergy of morphological operations of digital imagesand Hough transformation) of image recognition for apple detecting and counting. The study compared the results of three image analysis methods that can be used for counting apple fruits. They were validated, and their results allowed the recommendation of a method based on the YOLO algorithm for the proposed solution. It was based on the use of mass accessible devices (smartphones equipped with a camera with the required accuracy of image acquisition and accurate Global Navigation Satellite System (GNSS) positioning) for orchard owners to count growing apples. In our pilot study, three methods of counting apples were tested to create an automatic system for estimating apple yields in orchards. The test orchard is located at the University of Warmia and Mazury in Olsztyn. The tests were carried out on four trees located in different parts of the orchard. For the tests used, the dataset contained 1102 apple images and 3800 background images without fruits.

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GPS-BDS-Galileo double-differenced stochastic model refinement based on least-squares variance component estimation

Journal of Navigation ◽

10.1017/s0373463321000564 ◽

2021 ◽

pp. 1-16

Author(s):

Hong Hu ◽

Xuefeng Xie ◽

Jingxiang Gao ◽

Shuanggen Jin ◽

Peng Jiang

Keyword(s):

Stochastic Model ◽

Least Squares ◽

Stochastic Models ◽

Variance Component ◽

Satellite System ◽

Variance Component Estimation ◽

Short Baseline ◽

Component Estimation ◽

Zero Baseline ◽

Global Navigation Satellite

Abstract Stochastic models are essential for precise navigation and positioning of the global navigation satellite system (GNSS). A stochastic model can influence the resolution of ambiguity, which is a key step in GNSS positioning. Most of the existing multi-GNSS stochastic models are based on the GPS empirical model, while differences in the precision of observations among different systems are not considered. In this paper, three refined stochastic models, namely the variance components between systems (RSM1), the variances of different types of observations (RSM2) and the variances of observations for each satellite (RSM3) are proposed based on the least-squares variance component estimation (LS-VCE). Zero-baseline and short-baseline GNSS experimental data were used to verify the proposed three refined stochastic models. The results show that, compared with the traditional elevation-dependent model (EDM), though the proposed models do not significantly improve the ambiguity resolution success rate, the positioning precision of the three proposed models has been improved. RSM3, which is more realistic for the data itself, performs the best, and the precision at elevation mask angles 20°, 30°, 40°, 50° can be improved by 4⋅6%, 7⋅6%, 13⋅2%, 73⋅0% for L1-B1-E1 and 1⋅1%, 4⋅8%, 16⋅3%, 64⋅5% for L2-B2-E5a, respectively.

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Investigation of Pre-Earthquake Ionospheric and Atmospheric Disturbances for Three Large Earthquakes in Mexico

Geosciences ◽

10.3390/geosciences11010016 ◽

2020 ◽

Vol 11 (1) ◽

pp. 16

Author(s):

Christina Oikonomou ◽

Haris Haralambous ◽

Sergey Pulinets ◽

Aakriti Khadka ◽

Shukra R. Paudel ◽

...

Keyword(s):

Chemical Potential ◽

Atmospheric Model ◽

Satellite System ◽

Seismic Events ◽

Electron Content ◽

Total Electron ◽

Atmospheric Disturbances ◽

Global Ionospheric Maps ◽

Global Navigation Satellite ◽

Large Earthquakes

The purpose of the present study is to investigate simultaneously pre-earthquake ionospheric and atmospheric disturbances by the application of different methodologies, with the ultimate aim to detect their possible link with the impending seismic event. Three large earthquakes in Mexico are selected (8.2 Mw, 7.1 Mw and 6.6 Mw during 8 and 19 September 2017 and 21 January 2016 respectively), while ionospheric variations during the entire year 2017 prior to 37 earthquakes are also examined. In particular, Total Electron Content (TEC) retrieved from Global Navigation Satellite System (GNSS) networks and Atmospheric Chemical Potential (ACP) variations extracted from an atmospheric model are analyzed by performing statistical and spectral analysis on TEC measurements with the aid of Global Ionospheric Maps (GIMs), Ionospheric Precursor Mask (IPM) methodology and time series and regional maps of ACP. It is found that both large and short scale ionospheric anomalies occurring from few hours to a few days prior to the seismic events may be linked to the forthcoming events and most of them are nearly concurrent with atmospheric anomalies happening during the same day. This analysis also highlights that even in low-latitude areas it is possible to discern pre-earthquake ionospheric disturbances possibly linked with the imminent seismic events.

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Estimation of fractional cycle bias for GPS/BDS-2/Galileo based on international GNSS monitoring and assessment system observations using the uncombined PPP model

Satellite Navigation ◽

10.1186/s43020-021-00039-x ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Jin Wang ◽

Qin Zhang ◽

Guanwen Huang

Keyword(s):

Estimation Method ◽

Satellite Orbit ◽

Satellite System ◽

Assessment System ◽

Navigation Satellite ◽

Dual Frequency ◽

Fractional Cycle Bias ◽

The Stability ◽

High Consistency ◽

Global Navigation Satellite

AbstractThe Fractional Cycle Bias (FCB) product is crucial for the Ambiguity Resolution (AR) in Precise Point Positioning (PPP). Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide Lane (WL) and Narrow Lane (NL) combinations, the uncombined PPP model is flexible and effective to generate the FCB products. This study presents the FCB estimation method based on the multi-Global Navigation Satellite System (GNSS) precise satellite orbit and clock corrections from the international GNSS Monitoring and Assessment System (iGMAS) observations using the uncombined PPP model. The dual-frequency raw ambiguities are combined by the integer coefficients (4,− 3) and (1,− 1) to directly estimate the FCBs. The details of FCB estimation are described with the Global Positioning System (GPS), BeiDou-2 Navigation Satellite System (BDS-2) and Galileo Navigation Satellite System (Galileo). For the estimated FCBs, the Root Mean Squares (RMSs) of the posterior residuals are smaller than 0.1 cycles, which indicates a high consistency for the float ambiguities. The stability of the WL FCBs series is better than 0.02 cycles for the three GNSS systems, while the STandard Deviation (STD) of the NL FCBs for BDS-2 is larger than 0.139 cycles. The combined FCBs have better stability than the raw series. With the multi-GNSS FCB products, the PPP AR for GPS/BDS-2/Galileo is demonstrated using the raw observations. For hourly static positioning results, the performance of the PPP AR with the three-system observations is improved by 42.6%, but only 13.1% for kinematic positioning results. The results indicate that precise and reliable positioning can be achieved with the PPP AR of GPS/BDS-2/Galileo, supported by multi-GNSS satellite orbit, clock, and FCB products based on iGMAS.

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Improving DGNSS Performance through the Use of Network RTK Corrections

Remote Sensing ◽

10.3390/rs13091621 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1621

Author(s):

Duojie Weng ◽

Shengyue Ji ◽

Yangwei Lu ◽

Wu Chen ◽

Zhihua Li

Keyword(s):

Carrier Phase ◽

Local Area ◽

Satellite System ◽

High Accuracy ◽

Single Frequency ◽

Baseline Length ◽

Low Latitude ◽

Phase Measurements ◽

Network Rtk ◽

Global Navigation Satellite

The differential global navigation satellite system (DGNSS) is an enhancement system that is widely used to improve the accuracy of single-frequency receivers. However, distance-dependent errors are not considered in conventional DGNSS, and DGNSS accuracy decreases when baseline length increases. In network real-time kinematic (RTK) positioning, distance-dependent errors are accurately modelled to enable ambiguity resolution on the user side, and standard Radio Technical Commission for Maritime Services (RTCM) formats have also been developed to describe the spatial characteristics of distance-dependent errors. However, the network RTK service was mainly developed for carrier-phase measurements on professional user receivers. The purpose of this study was to modify the local-area DGNSS through the use of network RTK corrections. Distance-dependent errors can be reduced, and accuracy for a longer baseline length can be improved. The results in the low-latitude areas showed that the accuracy of the modified DGNSS could be improved by more than 50% for a 17.9 km baseline during solar active years. The method in this paper extends the use of available network RTK corrections with high accuracy to normal local-area DGNSS applications.

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Galileo L10 Satellites: Orbit, Clock and Signal-in-Space Performance Analysis

Sensors ◽

10.3390/s21051695 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1695

Author(s):

Constantin-Octavian Andrei ◽

Sonja Lahtinen ◽

Markku Poutanen ◽

Hannu Koivula ◽

Jan Johansson

Keyword(s):

Performance Indicators ◽

Satellite System ◽

Short Term ◽

Orbital Inclination ◽

Navigation Data ◽

Periodic Signals ◽

Global Navigation Satellite ◽

Minor Correction ◽

Very High

The tenth launch (L10) of the European Global Navigation Satellite System Galileo filled in all orbital slots in the constellation. The launch carried four Galileo satellites and took place in July 2018. The satellites were declared operational in February 2019. In this study, we report on the performance of the Galileo L10 satellites in terms of orbital inclination and repeat period parameters, broadcast satellite clocks and signal in space (SiS) performance indicators. We used all available broadcast navigation data from the IGS consolidated navigation files. These satellites have not been reported in the previous studies. First, the orbital inclination (56.7±0.15°) and repeat period (50680.7±0.22 s) for all four satellites are within the nominal values. The data analysis reveals also 13.5-, 27-, 177- and 354-days periodic signals. Second, the broadcast satellite clocks show different correction magnitude due to different trends in the bias component. One clock switch and several other minor correction jumps have occurred since the satellites were declared operational. Short-term discontinuities are within ±1 ps/s, whereas clock accuracy values are constantly below 0.20 m (root-mean-square—rms). Finally, the SiS performance has been very high in terms of availability and accuracy. Monthly SiS availability has been constantly above the target value of 87% and much higher in 2020 as compared to 2019. Monthly SiS accuracy has been below 0.20 m (95th percentile) and below 0.40 m (99th percentile). The performance figures depend on the content and quality of the consolidated navigation files as well as the precise reference products. Nevertheless, these levels of accuracy are well below the 7 m threshold (95th percentile) specified in the Galileo service definition document.

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