1,721,005 research outputs found
La deformazione gravitativa profonda del Monte Penna (La Verna): primi risultati dell'applicazione di un sistema di monitoraggio mediante GPS
No full textIntegration of LiDAR Data into a Regional Topographic Database for the Generation of a 3D City Model
No full textTo analyze the resilience of road infrastructures to natural and anthropic
hazards, the spatial and descriptive data provided by the Italian National Topographic
Data Base (NTDB) and the 3D data coming from the LiDAR data of the
“Ministero dell’Ambiente e della Tutela del Territorio e del Mare” (MATTM) can
be used. The two datasets, having different nature, need to be properly joined. The
aim of the work is the integration of the two datasets in a GIS environment for the
3D modelling of the anthropized territory and the optimization of the cartographic
bases. On a test area, crossed by a network of linear infrastructures of great strategic
importance and subjected to hydrogeological risk, an automated process has
been implemented and tested in ArcGIS Desktop environment, to homogenize the
data into the National Reference System. The planimetric component comes from
the NTDB whereas the LiDAR data have been used to attribute the elevation to
the extracted elements, to create the breaklines for a proper interpolation of the
heights to build the Digital Terrain Model (DTM), to extract the height of the
pitches of the buildings identified in the NTDB polygons, and finally to generate,
filter and optimize the contour lines. The proposed workflow and the methodologies
implemented also allowed the reconstruction of the volumes of each element
involved (infrastructures and buildings) and to correct the altimetric aberrations
present in the NTDB polygons
A Low-coast Mms Integrating GPS, Digital Compass and a camera to the Direct Georeferencing of Digital Images
No full textA low-cost, easily transportable Mobile Mapping System (MMS) was designed and built to obtain the direct georeferencing parameters of images; its components are a GPS receiver, a digital compass and a digital camera.
The main aim of the system is to directly define the orientation parameters of an image. The accuracy of the 3D coordinates of the points belonging to the object photographed is a consequence of the whole process which involves GPS positioning, compass angle determination, system calibration and any other useful auxiliary data that can be used to improve the accuracy of the system (GCPs coordinates, distance between the object and the camera, etc.). The tests carried out up until now have demonstrated the “theoretical”huge potential of the measuring system as well as its versatility. such as cars, helicopters and boats
Landslide monitoring using multitemporal terrestrial laser scanning for ground displacement analysis
No full textIn the analysis of the temporal evolution of landslides
and of related hydrogeological hazards, Terrestrial
Laser Scanning seems to be a very suitable technique
for morphological description and displacement
analysis. In this note we present some procedures
designed to solve specific issues related to
monitoring. A particular attention has been devoted
to data georeferencing, both during survey campaigns
and while performing statistical data analysis. The
proper interpolation algorithm for DEM generation
has been chosen taking into account the features of
the landslide morphology and of the acquired
datasets. For a detailed analysis of the different
dinamics of the hillslope, we identified some areas
with homogeneous behaviour applying in a GIS
environment a sort of rough segmentation to the grid
obtained differentiating two surfaces. This approach
has allowed a clear identification of ground
deformations, obtaining detailed quantitative
information on surficial displacements. These
procedures have been applied to a case study on a
large landslide of about 10 hectares, located in Italy,
which recently has severely damaged the national
railway line. Landslide displacements have been
monitored with TLS surveying for three years, from
February 2010 to June 2012. Here we report the
comparison results between the first and the last
survey
A Method for Obtaining a DEM with Curved Abscissa from MLS Data for Linear Infrastructure Survey Design
No full textThe sudden deterioration of the condition of linear infrastructure networks makes road management a complex task. Knowledge of the surface condition of the pavement is a requirement in order to estimate the causes of instabilities, select the appropriate action and identify all those sections that require urgent intervention. The mobile laser scanning (MLS) technique allows for a fast and safe diagnosis, thus making it possible to plan an early intervention program quickly and cost-effectively. This paper describes a methodology implemented with a twofold purpose: (i) the optimal definition, during the design phase, of the input parameters of the MLS survey (velocity of the vehicle and acquisition rate), defined through the study of the relationship between these parameters and the density of the scanned points and, therefore, with the resolution that allows the analysis of a certain type of pavement distress; (ii) the creation of a Digital Elevation Model with a curved abscissa (DEMc), specific for the analysis of road pavements. The field surveys made and the procedure developed allowed the velocity of the MLS to be associated with the resolution of the DEMc, and thus its capability to highlight distresses at different levels of severity. The creation of the road model is semiautomatic; the height value of each single node of the grid is estimated through spatial interpolation algorithms. Starting from experimental data, a few charts were created that relate the density of the point cloud to the variation of the acquisition rate, together with the minimum resolution. Depending on the type of distress analyzed, it is possible to infer the values to be respected of the parameters. In this way, it should be possible to draw up a few guidelines about MLS surveys addressing linear infrastructures focused on the optimization of the survey design, so as to identify strategies that can maximize benefits with the same available budget
Monitoraggio dell’evoluzione di una frana tramite Laser Scanning
No full textIn questa nota si descrive una applicazione della tecnica laser scanning terrestre al rilievo di una area di vaste proporzioni interessata da un fenomeno franoso di tipo lento. L’area interessata copre circa dieci ettari ed è attualmente monitorata con tecniche tradizionali. Utilizzando un sistema laser scanner di tipo long-range, sono stati effettuati diversi rilievi test per studiare la migliore metodologia da adottare. Per avere tutti i rilievi nel medesimo sistema di riferimento esterno e confrontarli nel tempo, non è stato possibile realizzare sul corpo di frana un frame di riferimento stabile nel tempo e i target sono stati ricollocati a ogni rilievo. E’ comunque possibile individuare vertici esterni alla frana materializzati stabilmente rispetto i quali rilevare con GPS punti di controllo ai quali riferire il rilievo laser. Per ogni rilievo sono state necessarie diverse nuvole di punti, ciascuna inizialmente riferita a un sistema strumentale, successivamente georeferenziate tramite target di forma sferica, riconoscibili nelle scansioni, i cui centro-sfera sono misurati con GPS rispetto a punti stabili esterni. In tal modo in ogni rilievo si possono ottenere DTM del corpo di frana riferiti a un sistema assoluto
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