Web based geoprocessing tool for coverage data handling
Keywords: Web Services, open source, WCS, WFS, WPS, Python, GDAL, PyWPS, and NDVI
Abstract. With the advancements in GIS technologies and extensive use of OGC Web Services, geospatial resources and services are becoming progressively copious and convenient over the network. The application of OGC WCS (Web Coverage Service) and WFS (Web Feature Service) standards for geospatial raster and vector data has resulted in an opulent pool of interoperable geodata resources waiting to be used for analytical or modelling purposes. The issue of availing geospatial data processing with the aid of standardised web services was attended to by the OGC WPS (Web Processing Service) 1.0.0 specifications (Schut, 2007) which elucidate WPS as a standard interface which serves for the promulgation of geo-processes and consumption of those processes by the clients. This paper outlines the design and implementation of a geo-processing tool utilizing coverage data. The geo-process selected for application is the calculation of Normalized Difference Vegetative Index (NDVI), one of the globally used indices for vegetation cover monitoring. The system is realised using the Geospatial Data Abstraction Library (GDAL) and Python. The tool accesses the WCS server using the parameters defined in the XML request. The geo-process upon execution, performs the computations over the coverage data and generates the NDVI output. Since open source technology and standards are being used more often, especially in the field of scientific research, so our implementation is also built by using open source tools only.