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Accuracy assessment of relative and precise point positioning online GPS processing services / Ahmed El Shouny in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

Public [article]  inJournal of applied geodesy > vol 13 n° 3 (July 2019) . - pp 215 – 227 Titre : Accuracy assessment of relative and precise point positioning online GPS processing services Type de document : Article/Communication Auteurs : Ahmed El Shouny, Auteur ; Yehia Miky, Auteur Année de publication : 2019 Article en page(s) : pp 215 – 227 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] Egypte [Termes IGN] estimation de précision [Termes IGN] positionnement différentiel [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] traitement de données GNSS Résumé : (auteur) Over the last few years, several institutions, research centers, and organizations have developed different strategies for GPS data processing and analysis to obtain high accurate coordinates. They are taking into considerations overcoming restrictions and limitations such as necessity of using relative positioning, time consuming, and high cost of different processing software. One of these developed strategies is the web–based online GNSS (Global Navigation Satellite Systems) processing service which estimates coordinates with centimeter or decimeter level accuracy. This study aims to represent the most popular of these services, namely AUSPOS, OPUS, APPS, GAPS, Trimble RTX, and CSRS–PPP, also to perform in-between comparison of these services with respect to their achieved accuracy using field observations with different durations. The obtained results were compared with a real field data measured using traditional relative positioning technique with high accuracy standards. The set of data used in this study was performed in the Eastern zone in Egypt. The results of this comparison indicate that these services can be used as an alternative method for relative positioning technique due to their simplicity, cost-effective and saving in time. They saved about 75 % from the time required for traditional method to produce coordinate with reasonable accuracy. The maximum standard deviation obtained was 15.4 cm from APPS service with time less than two hours, while the minimum standard deviation was 0.07 cm and obtained from CSRS–PPP with time duration from 6 to 12 hours. For achieving more accurate results, it is recommended to use time duration more than two hours. Numéro de notice : A2019-285 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0046 Date de publication en ligne : 24/04/2019 En ligne : https://doi.org/10.1515/jag-2018-0046 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93120 [article]

Evaluating the performance of using PPK-GPS technique in producing topographic contour map / Ahmed El Shouny in Marine geodesy, vol 40 n° 4 (July 2017)  

Public [article]  inMarine geodesy > vol 40 n° 4 (July 2017) . - pp 224 - 238 Titre : Evaluating the performance of using PPK-GPS technique in producing topographic contour map Type de document : Article/Communication Auteurs : Ahmed El Shouny, Auteur ; Nagy Yakoub, Auteur ; Magdy Hosny, Auteur Année de publication : 2017 Article en page(s) : pp 224 - 238 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] altitude orthométrique [Termes IGN] analyse comparative [Termes IGN] carte topographique [Termes IGN] courbe de niveau [Termes IGN] données GPS [Termes IGN] Egypte [Termes IGN] GPS en mode différentiel [Termes IGN] Nil (delta du) [Termes IGN] niveau à bulle [Termes IGN] post-traitement [Vedettes matières IGN] Altimétrie Résumé : (Auteur) The Global Positioning System (GPS) is considered as one of the most powerful tools that are used in geodetic works. It is increasingly considered as an alternative tool for conventional surveying techniques. The goal of this research paper is to produce a methodology for generating topographic contour maps using the post-processed kinematic differential GPS technique (PPK-GPS). The performance of this technique is assessed by comparing it with the traditional spirit-leveling technique taking into consideration the accuracy, time, and cost. The study area is located along the Mediterranean coast in the Rosetta area of the middle Delta in Egypt with a total area of about 39 km2. The field work includes 14 control points and about 50,000 PPK observations. In addition, 20 check cross sections that extend along the coastal line from Rosetta to El Burullus cities were observed using both spirit-leveling and GPS-PPK techniques. The results of the comparison indicate that the PPK-GPS technique can be used instead of spirit leveling in producing a topographic contour map with an accuracy of about 20 cm in orthometric height. We find that the PPK-GPS technique reduces the estimated time of leveling works in our study area by about 70%. Numéro de notice : A2017-667 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2017.1321594 En ligne : https://doi.org/10.1080/01490419.2017.1321594 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=87142 [article]