Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Reports on Geodesy

2 2003

Powiadomienia systemowe

Sesja wygasła!

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: hydrogeological catastrophe

Sortuj według:

Ogranicz wyniki do:

Registration of multitemporal landsat images: a local correlation approach

Gusella L.

Reports on Geodesy

2003

z. 2/65

269-278

The study of multitemporal dataset is a typical task of remote sensing analysis. The areas subjected to catastrophic events, such as earthquake, flooding, fire, can be empbasized by visual interpretation of images acquired on different periods. Seeing that the instant of a natural event is known, the acquisition and the subsequent interpretation of remotely sensed data can be focused on pre and post event image, calling master the first one, representing the normal situation, and slaves the post event images. Multiple techniques of enhancing can be used, like bands ratios, vegetation indexes comparison, principal components analysis and coherence calculation. Since these are essentially pixel-to-pixel image operations, a good registration between slaves (post-event images) and master (pre-event image) is the first result to achieve. The work presents a possible solution of registration problem in multitemporal data sets. The event studied is the earthquake occurred in the urban area surrounding the gulf of Izmit, in Marmara Sea (Turkey), August 17, 1999. Earthquake damage assessment by interpretation of remotely sensed data is carried out generally by visual recognition of differences in high-resolution images, and the main geometrical task is the georectification of datasets for mapping purpose. In this case, a very precise registration between image data sets is not essential to achieve significant results. While Landsat images have 30 meters of resolution, visual recognition of single, damaged buildings is not possible, but the study of multispectral bands can be helpful to find variation of suńace reflectance, caused by building collapse and presence of debris seattered on the roads. However, different position of satellite during acquisition (different view angles) and different sub-pixel features cause duplication/shifting of objects. This fault is particularly visible making color composites using the whole dataset. A local correlation filter can be used instead usual registration algorithms, trying to improve feature by feature matching and local coherence, which can be helpful to interpret variation on reflectance due to damage.

Database and GIS relative to geomatic surveys set up after the hydrological catastrophe in Sarno (Italy)

Barbarella M., Lenzi V.

Reports on Geodesy

2003

z. 2/65

254-263

This work deals with the creation or a Database and its reIative GIS concerning all the geomatic survey data collected during and after the emergency as a result or the hydrogeological event in Sarno, in South Italy. The catastrophic event was characterised by several landslides which occurred in May 1998. The purpose of this project is the creation of a database to organize and recover a great amount of geodetic data. Raw data were originated from different survey technologies, both traditional and modern: Photogrammetry, Airborne Laser Scanning, Remote Sensing, Ground Based Survey and Digitalization of Cartography. Several research teams also took part in processing the data and raw data were processed by different software packages producing different format files, primary data survey and processing data were thus collected to avoid dispersion of environmental information. As reported by many authors, the GIS and its reIated database are the most useful tools as a support in the decision-making strategies and in environmental data management. It should be pointed out that this project is in the strict sense a GIS concerning the specific case of Sarno and the specific management of geodetic data.