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The effect of tropospheric delay on GPS height differences along the Equator / J. Dodo in SaLIS Surveying and land information science, vol 68 n° 3 (September 2008)

Public [article]  inSaLIS Surveying and land information science > vol 68 n° 3 (September 2008) . - pp 145 - 154 Titre : The effect of tropospheric delay on GPS height differences along the Equator Type de document : Article/Communication Auteurs : J. Dodo, Auteur ; M. Kamarudin, Auteur ; M. Yahya, Auteur Année de publication : 2008 Article en page(s) : pp 145 - 154 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement [Termes IGN] antenne GPS [Termes IGN] correction du signal [Termes IGN] équateur (géodésie) [Termes IGN] erreur systématique [Termes IGN] GPS en mode cinématique [Termes IGN] hauteur ellipsoïdale [Termes IGN] Malaisie [Termes IGN] nivellement par GPS [Termes IGN] positionnement cinématique en temps réel [Termes IGN] propagation troposphérique [Termes IGN] zone équatoriale Résumé : (Auteur) The fundamental issue in GPS positioning is the ability to mitigate all the potential errors and biases in the system. The atmosphere related errors of ionosphere and troposphere constitute one of these potential errors. The tropospheric effect is much more pronounced at the equatorial region due to its hot and wet conditions. This significantly affects the GPS signal due to the variability of the refractive index, which in turn affects the accuracy of GPS positioning, especially in the height components. This paper presents a study conducted in Malaysia located at the equatorial region, to investigate the impact of tropospheric delay on GPS height variation. Five GPS reference stations forming part of the Malaysian real-time kinematic GPS network (MyRTKnet) in Johor were used. RINEX data from these stations were integrated with GPS and ground meteorological data observed from a GPS station located at the Universiti Teknologi Malaysia (UTM), at varying antenna heights for each session of observation in four campaigns with each campaign lasting for three days. A computer program called TROPO.exe was developed based on Saastamoinen tropospheric model. The result shows variations in the height component of GPS measurement with a maximum value of 119.100 cm and a minimum value of 37.990 cm. Similarly, the results show that the tropospheric delay is a distance-dependent error which varies with changes in meteorological condition. Furthermore, the results of simulated data show a decrease in tropospheric delay with increase in antenna height. Copyright SaLIS Numéro de notice : A2008-411 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83665 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
121-08031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Landslide morphology analysis model based on LiDAR and topographic dataset comparison / Sagi Dalyot in SaLIS Surveying and land information science, vol 68 n° 3 (September 2008)

Public [article]  inSaLIS Surveying and land information science > vol 68 n° 3 (September 2008) . - pp 155 - 170 Titre : Landslide morphology analysis model based on LiDAR and topographic dataset comparison Type de document : Article/Communication Auteurs : Sagi Dalyot, Auteur ; E. Keinan, Auteur ; Y. Doytsher, Auteur Année de publication : 2008 Article en page(s) : pp 155 - 170 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] analyse comparative [Termes IGN] croissance urbaine [Termes IGN] données lidar [Termes IGN] données localisées numériques [Termes IGN] effondrement de terrain [Termes IGN] géomorphologie locale [Termes IGN] modèle numérique de surface [Termes IGN] surveillance géologique [Termes IGN] zone urbaine dense Résumé : (Auteur) The natural trend of megacities is to expand from their centers to outlying areas in order to accommodate rapid population growth. Urban areas situated near steep, mountainous terrain or water sources may suffer from landslides, which are one of the most common natural disasters. This paper outlines a new approach in which airborne laser altimetry is used to automatically identify and model landslide occurrences within the acquired data. Dense and accurate light detection and ranging (LiDAR) topographic observations are modeled and compared to an existing digital elevation model (DEM) of the area acquired at an earlier stage. The standard direct superimposition comparison mechanism, which ignores the datasets' inherent interrelations, usually results in an incorrect modeling outcome. A new modeling concept is proposed that initially monitors the inherent global incongruities by georeferencing the two datasets. These incongruities are then utilized in a novel geospatial matching procedure that makes it possible to achieve a precise and correct local modeling mechanism. The hierarchical comparison concept presented accurate results in automatic identification of landslide phenomena, making it possible to precisely assess their morphology. Copyright SaLIS Numéro de notice : A2008-412 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83666 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
121-08031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Technical challenges in developing flexible land records software / A. Muhsen in SaLIS Surveying and land information science, vol 68 n° 3 (September 2008)

Public [article]  inSaLIS Surveying and land information science > vol 68 n° 3 (September 2008) . - pp 171 - 181 Titre : Technical challenges in developing flexible land records software Type de document : Article/Communication Auteurs : A. Muhsen, Auteur ; Michael Barry, Auteur Année de publication : 2008 Article en page(s) : pp 171 - 181 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cadastre numérique [Termes IGN] base de données foncières [Termes IGN] base de données relationnelles [Termes IGN] cadastre étranger [Termes IGN] enregistrement immobilier [Termes IGN] mise à jour de base de données [Termes IGN] propriété foncière Résumé : (Auteur) Peri-urban zones in many developing world cities are characterized by slums and informal settlements. Societies in which oral traditions, stories, dances, cultural icons, and artifacts give effect to the land tenure system struggle to preserve the primary elements of their culture in a modern technological society and struggle to lay claim to “their” territories which governments frequently regard as vacant state-owned land. Post-conflict societies often deal with refugees flowing into an area, returning refugees, internally displaced persons, and collapsed land-administration institutions, providing opportunities for powerful coalitions of individuals to grab vacant land, and newly established state institutions often appropriate and reallocate vacant land that is clearly owned by someone who has fled the conflict. Conventional land registration and cadastral survey systems are seldom designed to cater to the complex set of social relationships that characterize these and numerous similar situations. Our research group is developing a software system that should be simple in its design yet sufficiently flexible to cater to a combination of different land-related applications in areas where official recognition of land tenure is uncertain. Accordingly, a most simple structure for a cadastral information model that can handle multimedia data is being explored. The model incorporates four, inter-related classes: (1) Person (representing rights holders, e.g., juristic persons, companies, and social structures); (2) Reference Instrument (e.g., a title, a deed, or some other form of reference); (3) Land Object (which includes parcels, dwellings, trees, or trap lines); (4) Media Item (includes a wide range of media files such as video clips, audio files, maps, images, and/or photographs). This model provides a great deal of flexibility, and—if used properly—a range of different types of data can be stored, related, mixed, and matched. This paper describes some of the technical challenges involved in developing the software. Copyright SaLIS Numéro de notice : A2008-413 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83667 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
121-08031	RAB	Revue	Centre de documentation	En réserve L003	Disponible