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Assessment of orthoimage and DEM derived from ZY-3 stereo image in Northeastern China / Y. Dong in Survey review, vol 48 n° 349 (July 2016)  

Public [article]  inSurvey review > vol 48 n° 349 (July 2016) . - pp 258 - 268 Titre : Assessment of orthoimage and DEM derived from ZY-3 stereo image in Northeastern China Type de document : Article/Communication Auteurs : Y. Dong, Auteur ; W. Cheng, Auteur ; Hoon Chang, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 258 - 268 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] Chine [Termes IGN] image ZiYuan-3 [Termes IGN] MNS ASTER [Termes IGN] modèle numérique de surface [Termes IGN] modèle par fonctions rationnelles [Termes IGN] modèle stéréoscopique [Termes IGN] orthoimage Résumé : (auteur) ZiYuan-3 (ZY-3, meaning Resource-3) is China's first civilian multispectral satellite with high-resolution stereo mapping capability. The along-track stereo images of ZY-3 allow the generation of digital elevation models (DEMs) for various mapping applications. This article evaluated the precision of the derived stereo DEM and orthoimages of ZY-3 data for a test site in Northeastern China. Pixel offset and GPS survey data were used to evaluate the image products. Orthoimages were derived by incorporating rational polynomial coefficients (RPCs) of the satellite orbits and the reference DEMs, including the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (GDEM) and ZY-3 stereo elevation model. The generations of orthoimages were categorised into four approaches depending on the RPCs, control points and/or reference DEMs used. When only the ASTER GDEM was used, the derived orthoimages of the forward and backward viewing sensors showed clear pixel offsets against the GPS check points (CKPs). For example, the offsets of the orthoimage derived using forward-looking image were 13·58 and 26·50 m, in x (easting) and y (northing) directions, respectively. These results also indicated that the pixel offset vectors between the forward and backward orthoimages was systematic which was caused by the error in the RPCs. The second and third approaches were to generate the ZY-3 stereo DEMs first, with and without the use of ground control points (GCPs), and then used the stereo DEMs to generate the orthoimages of the forward and backward looking images. The forth approach used both GCPs and ASTER GDEM to generate the orthoimages. The results showed the use of four GCPs in the process improved the accuracy of the orthoimages. Therefore, ZY-3 can deliver the DEM and orthoimage products to meet the accuracy requirement of the national 1 : 50 000 mapping with four well distributed GCPs. Numéro de notice : A2016-623 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1179/1752270615Y.0000000027 En ligne : https://doi.org/10.1179/1752270615Y.0000000027 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81825 [article]

A point-based methodology for the automatic positional accuracy assessment of geospatial databases / Juan J. Ruiz-Lendínez in Survey review, vol 48 n° 349 (July 2016)  

Public [article]  inSurvey review > vol 48 n° 349 (July 2016) . - pp 269 - 277 Titre : A point-based methodology for the automatic positional accuracy assessment of geospatial databases Type de document : Article/Communication Auteurs : Juan J. Ruiz-Lendínez, Auteur ; Francisco Javier Ariza-López, Auteur ; Manuel A. Ureña-Cámara, Auteur Année de publication : 2016 Article en page(s) : pp 269 - 277 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] base de données localisées [Termes IGN] évaluation [Termes IGN] points homologues [Termes IGN] polygone [Termes IGN] précision du positionnement [Termes IGN] qualité des données Résumé : (auteur) This paper is based on our earlier paper (Ruiz-Lendínez et al., 2013) of this work and its new contribution is to develop a point-based methodology for the automatic assessment of positional and geometric components of spatial data. The starting point for our approach is the set of homologous polygons obtained according to the methodology developed in Ruiz-Lendínez et al. (2013). From these pairs of polygons, we first have identified and computed homologous points using a metric for comparing polygonal shapes defined by Arkin et al. (1991) and then we have applied a point-based standard developed for assessing the positional accuracy of spatial data. Specifically, we have employed the National Standard Spatial Data Accuracy (NSSDA) standard. The results obtained demonstrate the viability of this point-based evaluation and its potential compared to traditional methods. Numéro de notice : A2016-624 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1179/1752270615Y.0000000030 En ligne : https://doi.org/10.1179/1752270615Y.0000000030 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81827 [article]

An adaptive stochastic model for GPS observations and its performance in precise point positioning / J. Z. Zheng in Survey review, vol 48 n° 349 (July 2016)  

Public [article]  inSurvey review > vol 48 n° 349 (July 2016) . - pp 296 - 302 Titre : An adaptive stochastic model for GPS observations and its performance in precise point positioning Type de document : Article/Communication Auteurs : J. Z. Zheng, Auteur ; F. Guo, Auteur Année de publication : 2016 Article en page(s) : pp 296 - 302 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] bruit (théorie du signal) [Termes IGN] correction ionosphérique [Termes IGN] fenêtre (informatique) [Termes IGN] mesurage de pseudo-distance [Termes IGN] modèle stochastique [Termes IGN] positionnement par GPS [Termes IGN] récepteur GPS [Termes IGN] temps réel Résumé : (auteur) In this paper, the stochastic characteristics of Global Positioning System (GPS) pseudo-range noise as influenced by several factors such as receiver type, frequency, and ionosphere environment are analysed. The results indicate that the noise level of GPS observations is significantly affected by these factors. Moreover, the noise level is so mutable that it cannot be generalised and described by a uniform empirical model. Even for the same satellite, the noise level of observations may fluctuate sharply in both spatial and temporal resolution. To establish a reasonable stochastic model, a recursive sliding window method for estimating pseudo-range noise in real time is introduced. The effectiveness of the proposed method is verified by specific computational examples. Numéro de notice : A2016-626 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000033 En ligne : https://doi.org/10.1179/1752270615Y.0000000033 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81842 [article]

A comparative analysis of measurement noise and multipath for four constellations: GPS, BeiDou, GLONASS and Galileo / Changsheng Cai in Survey review, vol 48 n° 349 (July 2016)  

Public [article]  inSurvey review > vol 48 n° 349 (July 2016) . - pp 287 - 295 Titre : A comparative analysis of measurement noise and multipath for four constellations: GPS, BeiDou, GLONASS and Galileo Type de document : Article/Communication Auteurs : Changsheng Cai, Auteur ; Chang He, Auteur ; Rock Santerre, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 287 - 295 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] code GNSS [Termes IGN] constellation BeiDou [Termes IGN] constellation Galileo [Termes IGN] constellation GLONASS [Termes IGN] constellation GPS [Termes IGN] phase [Termes IGN] rapport signal sur bruit [Termes IGN] trajet multiple Résumé : (auteur) With the rapid development of BeiDou system (BDS) and steady progress of Galileo system, the current GNSS (Global Navigation Satellite System) constellations consist of GPS, GLONASS, BeiDou and Galileo. The real signals from the four constellations have been available, which allows us to analyse and compare their measurement noises and multipath effects. In this study, a zero-baseline test is conducted using two ‘Trimble NetR9’ receivers to assess and compare the noises and multipath of measurements on multiple frequencies from the four satellite systems. The zero-baseline double difference approach is utilised to analyse the receiver noises. The code multipath combination and triple-frequency carrier phase combination approaches are exploited to analyse a comprehensive effect of the multipath and noises on the code and carrier phase measurements, respectively. Based on the analysis of the zero-baseline dataset, the results indicate that the code measurement noise levels range from 5 to 25 cm while the carrier phase noise levels vary within 0.9–1.5 mm for different frequencies and constellations. The code multipath and noise (CMN) level for GLONASS is the largest with a root mean square (RMS) value of 39 cm on both G1 and G2 frequencies whereas the Galileo code measurements exhibit a smallest level on the E5 frequency with a RMS value of only 10 cm. The RMS of the carrier phase multipath and noises (PMN) ranges from 1.3 to 2.6 mm for BeiDou and Galileo satellites. By contrast, the triple-frequency carrier phase combinations from the GPS Block IIF satellites demonstrate a much larger RMS value of 5.6 mm owing to an effect of inter-frequency clock biases. Numéro de notice : A2016-625 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000032 En ligne : https://doi.org/10.1179/1752270615Y.0000000032 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81843 [article]

The contribution of laser scanning technology in the estimation of ancient Greek monuments' deformations / G. D. Georgopoulos in Survey review, vol 48 n° 349 (July 2016)  

Public [article]  inSurvey review > vol 48 n° 349 (July 2016) . - pp 303 - 308 Titre : The contribution of laser scanning technology in the estimation of ancient Greek monuments' deformations Type de document : Article/Communication Auteurs : G. D. Georgopoulos, Auteur ; E. C. Telioni, Auteur ; A. Tsontzou, Auteur Année de publication : 2016 Article en page(s) : pp 303 - 308 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] déformation d'édifice [Termes IGN] Grèce [Termes IGN] monument historique [Termes IGN] patrimoine immobilier [Termes IGN] restitution lasergrammétrique [Termes IGN] surveillance d'ouvrage [Termes IGN] temple Résumé : (auteur) Terrestrial laser scanning technology is nowadays more and more used for the documentation of cultural heritage monuments. The thorough exploitation of the main advantage of terrestrial laser scanners (TLS) that is the acquisition of extremely dense discrete points in a relatively small time period leads to detailed 3D representation of the monument, overcoming possible difficulties such as limited accessibility. Most often, this 3D representation is used for the monument's documentation as well as for virtual tours in, out or around it. This detailed documentation can be used for one more purpose: the estimation of the deformation that its elements have experienced through the centuries and, following, the monument's restoration, provided that, its' initial, constructional geometry is known. In this paper, research towards this goal is presented, dealing with the estimation of the deformations of a column of the ancient temple of Zeus in Nemea Greece using TLS technology. This column is standing erect since the temple's construction in 330 BC and it has been subject to serious deformations because of various causes. Numéro de notice : A2016-627 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1179/1752270615Y.0000000035 En ligne : https://doi.org/10.1179/1752270615Y.0000000035 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81844 [article]