1,721,232 research outputs found
Time series processing of MODIS Satellite data for landscape epidemiological applications
No full textThis paper reports on the processing of time series of MODIS NDVI/EVI and LST satellite data in a Geographical Information System (GIS). The required data preparations for the integration of MODIS data in GIS is described with focus on the reprojection from MODIS/Sinusoidal projection to national coordinate systems. To remove low quality pixels, the MODIS quality maps are utilised. We explain subsequent filtering of Land Surface Temperature maps with an outlier detector to eliminate originally undetected cloud pixels. Further analysis of time series is briefly discussed as well as related landscape epidemiological applications in the field of tick-borne disease
GIS processing of MODIS and ASTER remote sensing data
No full textThis technical report reflects experiences with processing of MODIS and ASTER satellite data in a Geographical Information System (GIS). Technical details of these satellite instruments are covered as well as selected derived data products. The report also deals with data preprocessing for the GIS usage. Expecially the import of modis data into a GIS requires extra steps as most MODIS data are delivered in the typically unsupported ISIN projection. Related to the reprojection the ISIN shift problem is discussed. Furthermore the import of ASTER image and ASTER DEM data into GIS is describe
MODIS time series remote sensing for epidemiological modeling
No full textIn epidemiological modeling, survey data are usually collected at sampling sites and then regionalized within Geographical Information Systems (GIS). To enhance the data density, continuous field data such as land surface temperatures (LST), snow coverage, vegetation indices are commonly derived from satellite data. The recent launches of the new satellite systems Terra and Aqua significantly improve the situation of data availability for scientific purposes and epidemiological studies and predictions. The most interesting sensor onboard is MODIS which daily delivers two global coverages
at 250m (Red, NIR), 500m (MIR) and 1000m resolution (TIR).
The paper focuses on two of the numerous MODIS data products: Land Surface Temperatures (LST), and vegetation index 16-day composites. The integration of MODIS satellite data into a GIS requires several pre-processing steps, such as the reprojection from MODIS-ISIN or MODIS-SIN projections to another more common projection (UTM, national coordinate
systems etc.). The resulting maps are filtered pixelwise by applying the related quality maps which are provided along the data products. Due to limitations in the official cloud detection algorithm used to create these land surface temperature quality maps, an outlier detection has been implemented. Based on the scene statistics, this outlier filter aims at removing all pixels which contain cloud temperatures instead of the
desired land surface temperatures. Another set of MODIS time series data are NDVI and EVI vegetation indices. They can be implemented into epidemiological models to introduce vegetation dynamics. The 16-day composite product minimizes cloud cover and reflects
at a sufficient temporal resolution the current vegetation status. The integration of MODIS data into epidemiological research enhances the spatio-temporal resolution of climatological data in particular in mountainous regions. The study area, a region of approximately 20000 sqkm, is of complex terrain with elevation ranging from nearly sea level to 3800 meters with a varying density of meteorological stations. The recent implementation of general time series processing for GRASS raster maps supports univariate statistics for a series of MODIS scenes. By selecting various time ranges and operators, a number of indicators can be calculated. The comparison of LST with ground truth time series from climatic stations showed that the LST match quite well with ground temperatures. While surface and aerial temperatures differ by definition, it is possible to transform surface to aerial temperatures by a regression model. Results and comparisons will be presented in the pape
Free General-purpose GIS. A Geographic Resources Analysis Support System
No full textThe Geographic Resources Analysis, GRASS, a general purpose GIS originally developed by U.S. Army Corps of Engineers Laboratory, has grown into one of the main components of Open Source and Free Software geospatial compuational infrastructure. Current developments led by international team of programmers, focus on improving the 2D and 3D raster and vector data processing and analysis tools and 3D visualization capabilities in the wake of publishing of the code under GPL in 1999. Applications in the area of epidemiology, coastal management and water flow modelling provide a snapshot of the capabilitie
Moving to smaller libraries via clustering and genetic algorithms
No full textThere may be several reasons to reduce a software system to its bare bone removing the extra fat introduced during development or evolution. Porting the software system on embedded devices or palmtops are just two examples. This paper presents an approach to re-factoring libraries with the aim of reducing the memory requirements of executables. The approach is organized in two steps. The first step defines an initial solution based on clustering methods, while the subsequent phase refines the initial solution via genetic algorithms. In particular, a novel genetic algorithm approach, considering the initial clusters as the starting population, adopting a knowledge-based mutation function and a multi-objective fitness function, is proposed. The approach has been applied to several medium and large-size open source software systems such as GRASS, KDE-QT, Samba and MySQL, allowing to effectivel
GRASS 5.7 per iPAQ H3870
No full textDopo aver illustrato brevemente le caratteristiche di un generico software GIS (Geographic Information System), si presenterà schematicamente il Geographic Resources Analysis Support System (GRASS), la più importante implementazione Open Source GIS. Verrà indicata poi la procedura dettagliata per la creazione di un pacchetto Debian/ARM 1 di GRASS 5.7 su un Personal Digital Assistant iPAQ H3870 dotato di sistema operativo Debian/Linux (Intimate), ed attraverso alcuni esempi si mostreranno alcune possibili applicazioni ed i vantaggi derivanti dall'utilizzo congiunto di dispositivi palmari Linux e GRASS. Il lavoro svolto costituisce parte integrante del progetto WILMA (Wireless Internet and Location Management Architecture) condotto all'ITC-irst (Centro per la Ricerca Scientifica e Tecnologica) di Trento, in particolare per quanto riguarda
l'aspetto della gestione delle informazioni legate alla mobilità dell'utente con l'utilizzo di dispositivi handheld. Il pacchetto Debian/ARM di GRASS 5.7 realizzato,
con relativi binari e sorgenti, è disponibile per la sperimentazione in http://mpa.itc.
it/markus/grass57/debian
- …
