1,720,987 research outputs found
Three-dimensional multispectral classification and its application to early seismic damage assessment
No full textThe recent seismic events that have affected different areas of the planet point out the need to respond quickly to emergencies caused by these events; for this reason a semi-automatic method was experimented which would provide information concerning the damaged buildings in the study area through satellite images. In September 1997 an earthquake hit the study area, causing significant damage to a number of towns and villages in the area. This research attempts to: a) improve the digital surface model extracted from Ikonos satellite images covering an area of central Italy (Foligno, Umbria), through the pre-processing of raw images and manual editing b) study the best DSM models to improve the detection of height differences, mainly in urban areas, and evaluate the results of the land cover classification as further data for detecting changes in building distribution. DSM obtained by three-dimensional maps have been compared with DSM extracted directly from aerial stereo pairs using different approaches. The innovative aspect of the experiment is that of wanting to evaluate whether the combined use of multispectral classification techniques and altimetric aspects taken from high-resolution satellite images can make the recognition of changes to buildings affected by the earthquake more robust. The same methodology can be used also for updating existing medium-scale maps; in this case as well, the comparison of data regarding the same area but for different periods is important
Coastline Detection Using High Resolution Multispectral Satellite Images
No full textIn the last 50 years the inhabitants of the 19 municipalities along the Abruzzo coast have doubled, and a stronger impact of the activities connected with the tourism has been experienced. The area, naturally exposed to the effects of changes of the sea level, has been interested by a dramatic increase of erosion, due to the reduction of the solid transport from rivers to the sea, as a consequence of extensive works carried out on the watersheds to mitigate extreme rainfall and consequent flooding. The availability of data acquired by different sensors on the last few decades might be useful to assess overall accretion/erosion trend of coastline, whereas combination of different observations taken in a restricted timeframe may provide interesting inputs for detailed studies (e.g. about the local impact of coastline protection works). In the present paper is proposed a methodology for the coastline identification from WorldView-2 images, available in 8 spectral bands, with 0.5 m of spatial resolution for panchromatic images and 1.8 m for the multispectral channels. In particular, a pixel based multispectral classification was used to identify various types of land cover. The 8 bands allow to get good results both in the classification process and with NDVI, NDWI, SAM, FM algorithms, for the identification of various land cover and in particular to separate dry sand from wet sand. Interesting results were obtained testing an algorithm that evaluates the relative depth of the water using the “coastal blue” band. Better results can surely be obtained by using elevation data (geoid models and digital terrain models) integrated with radiometric information. Very interesting is the comparison of the estimated coastline with such methodology and a topographic map of same area. This comparison highlights the changes in the study area. The possible applications of the proposed techniques are many, such as map updates, but also coastal change monitoring
Individuazione della linea di costa mediante immagini satellitari multispettrali ad alta risoluzione
No full textImproving traditional change detection with dsm for update cartography in urbanized areas after seismic events
No full textImmagini ad alta ed altissima risoluzione per l’aggiornamento della cartografia dell’Aquila
No full textInitial results of the Italina project on direct georeferencing in aerial photogrammetry
No full textUtilisation d’images à haute et très haute résolution pour la mise à jour de la carte de l’Aquila (Italie)
No full text
Improving traditional change detection with dsm for update cartography in urbanized areas after seismic events
No full text- …
