1,721,052 research outputs found
Planning GNSS realistico per applicazioni statiche e cinematiche
No full textThe more and more spread presence of GNSS Permanent Station Networks makes the satellite survey techniques more simpler, quicker and cheaper, allowing the technician to obtain easily high precisions. However, the result and, above all, the speed of GNSS survey campaign get an advantage out of accurate planning, especially where the site to survey has characteristics that make the satellite observations difficult.
In the present work applications performed with the updated version of a planning software, previously developed by one of the author, are illustrated. The software, realized as code integrated in the free and open source GIS GRASS, allows to obtain realistic satellite visibility maps and PDOP index maps taking into account the obstructions to satellite signals due to terrain morphology or buildings, through digital surface models of the interesting area. The procedure, called realistic planning, may be used to find optimal areas in which perform a survey in a given temporal window, or to find the best hour at which plan the survey campaign; it may be applied either to whole areas and to specific trajectory, in adhesion to the terrain or at a given elevation, known the mean velocity of the vehicle. The code was also integrated with the calculus of an index of visibility percentage with respect to the number of satellite observable without obstructions, so to make easy the choice of the site for the new permanent stations.
By means of such software, a comparative analysis of realistic satellite visibility and PDOP index for a particularly complex area in function of the different GNSS satellite constellations in the course of 24 hours, for static and cinematic applications, and an analysis of the visibility percentage index were performed. The results underline the important contribution of multi-constellations to satellite positioning, mainly in difficult areas, even if actually not yet optimal to allow good surveys in every moment of the day
Planning GNSS realistico.
No full textThe more and more spread presence of GNSS Permanent Station Networks makes the satellite survey techniques more simpler, quicker and cheaper, allowing the technician to obtain easily sub-decimetric precisions. However, the result and, above all, the speed of GNSS survey campaign get an advantage out of accurate planning, especially where the site to survey has characteristics that make the satellite observations difficult. To facilitate the search of sites suitable for the installation of GNSS permanent stations, a planning software, previously developed by one of the author, has been updated; it allows to obtain realistic satellite visibility maps, taking into account of the terrain morphology or buildings through digital surface models of the interesting area. By means of such software, a comparative analysis of satellite visibility in function of the different GNSS satellite constellation in the course of 24 hours in a particularly complex area was performed. The evaluation of satellite numbers realistically visible is integrated with an index of visibility percentage with respect to the number of satellite observable without obstructions, so to make easy the choice of the site for the future GNSS permanent stations of Piedmont Region
Inversione e filtraggio tramite collocazione di dati vettoriali in geodesia
No full textThe application of collocation always requires the estimation of a covariance function by fitting an empirical covariance function with a covariance function model. The covariance function model must be choosen inside a dictionary of positive definite functions. The construction of matrix value covariance function models for vector value data is treated for the application of collocation to the filtering and inversion of gravimetric and gradiometric data
Rete di stazioni permanenti per il posizionamento satellitare come Servizio della Regione Liguria: una proposta
No full textThe proposal effected to the Computer science Systems Service of the Liguria Region
for the part of survey group of the University of Genoa, foresees the institution of a
Survey Regional Service that concerns the realization, management and analysis of, at
least, 6 GPS permanent stations (+Glonass and in the future also Galileo) on the
regional territory. It is foreseen the institution of a data collection center, elaboration and
analysis of the data related to the whole net. The quality of the datum is not only of
primary importance as it regards the observations and the relative output, but also as
continuity and guarantee of the service. In synthesis, the Service has to provide to the
local users the necessary tools to become the operations of satellite survey more
economic, less complex and more slender, assisting the own users, studying and
proposing new applications.
Because of the particular conformation of the Liguria territory, the distribution of the
permanent stations cannot sufficiently be homogeneous according to a superficial point
of view. This is possible if the number of installations increase a lot; from here the
importance of possible interactions with analogous services of bordering Regions.
The institution of a Regional Setting Service of the Liguria Region must be seen how a
service offered to the territory in the different institutional activities
Programma Anblock per triangolazione aerea a modelli indipendenti
No full textCi si propone di chiarire quali sono i principi di funzionamento, i limti di validità, le potenzialità ed i vantaggi del programma ANBLOCK, che consente di compensare rigorosamente a modelli indipendenti, su personal computer, anche grossi blocchi di triangolazione
L'altimetria con il GPS
No full textIl presente lavoro tratta i problemi connessi con l'utilizzo del GPS nelle reti di livellazione effettuate in ambito locale, essenzialmente per applicazioni di tipo cartografico. Lo si può considerare suddiviso in tre parti principali: la prima illustra le più importanti cause di errore della tecnica stessa e come esse di ripercuotono sui risultati di una campagna altimetrica, la seconda esamina invece l'attuale grado di conoscenza del geoide, fondamentale nella applicazione altimetrica della tecnica GPS. Infine, la terza ed ultima parte rappresenta una proposta operativa per la compensazione di una rete altimetrica in ambito locale, utilizzando sia le misure GPS che la conoscenza del geoide
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