The package functionalities are focused for the download and processing of multi-temporal datasets from MODIS sensors. All standard MODIS grid data can be accessed and processed by the package routines. The package is still in alpha development and not all the functionalities are available for now. One of the main capabilities is the retrieval of data from remote sources by defining simple spatial and temporal subsets. The retrieval of the data is performed or through a connection to the main MODIS ftp data pools (LP DAAC and LAADS) or through the MODIS Web service based on SOAP (Simple Object Access Protocol). Further it is possible to define user defined sources and make accessible also data within local area network. As an example, the download of all MODIS (Terra and Aqua) NDVI 16 Days composite at 250 m data covering Austria, is performed by the command getHdf(“product=”MxD13Q1”, extent=”Austria”). To limit the temporal coverage to the year 2005 the user has just to add begin=”2005001” and end=”2005365” within the function arguments. Once data is downloaded the package holds pre-processing functionalities. The main pre-processing capabilities are, mosaicking, resampling, SDS extraction and bit coded SDS decoding. These are mainly performed by using an interface to the MODIS re-projection Tool (MRT,https://lpdaac.usgs.gov/tools/modis\_reprojection\_tool) or to the Geospatial Data Abstraction Library (GDAL,http://www.gdal.org/). The download and the pre-processing on user side can be performed by typing a single function and a few simple parameters. The package defaults are set to fit most of the user needs. This makes it possible to use the functionality of the package without having many skills in the programming language R. Output of the pre-processing are standard format raster files usable in any other software that handles remote sensed images. For example the generation of a multi-temporal image stack for the year 2005 over Austria using MRT the function is: runMrt(product=”MxD13Q1”, extent=”austria”, begin=”2005001”, end=”2005365”) this function internally contains the getHdf function that handles the data acquisition. Than using internally MRT the data is re-projected, mosaicked and cropped to a bounding box containing Austria. The main-processing part (currently not available) contains functions focused on the processing of multi-temporal data sets. Further work on the MODIS package will focus on the smoothing and filtering, trend analysis, change-detection and extraction of phenological parameters. The package outputs are aligned with the major geospatial R packages, providing so the possibility to benefit from mostly all geospatial tools sets within R.
|Title of host publication||Proceedings of the 1st EARSeL Workshop on Temporal Analysis of Satellite Images, 23 25 May, Mykonos, Greece|
|Place of Publication||Mykonos, Greece|
|Publication status||Published - 2012|
|Event||1st EARSeL Workshop on Temporal Analysis of Satellite Images, Mykonos, Greece - |
Duration: 23 May 2012 → 25 May 2012
|Workshop||1st EARSeL Workshop on Temporal Analysis of Satellite Images, Mykonos, Greece|
|Period||23/05/12 → 25/05/12|