Geomatic techniques for disseminating processed remotely sensed open data in an interactive WebGIS

There has been increasing research on the influence of environmental indicators in policy and management contexts. To provide meaningful trend studies or comparison analyses, collecting geospatial data is one of the most important tasks for many spatial information users, but persistent data gaps still remain. Satellite remote sensing has the potential to overcome these gaps by providing continuous coverage over decadal time scales for important environmental parameters. However significant barriers to the use of satellite data for indicator development persist. These relate to difficulties in accessing and using data, differences between decision-makers’ parameters of interest and what satellites actually measure , limited collaboration between the environmental measurement and Earth observing satellite communities to develop robust satellite based indicators, as well as technical issues such as cloud cover interfering with satellite data collection, and a lack of cross-cutting technical and funding resources. In this paper we preliminary discuss methods for collecting raster data in a geodata base by processing open multi-temporal and multi-scale satellite data aimed at retrieving indicators for desertification phenomenon (i.e. land cover/land use analysis, vegetation indices, trend analysis, etc.). Then we describe a prototype created for disseminating geospatial raster results (processed imagery and statistical map analysis) through an interactive WebGIS. The system was designed using a suite of open source WebGIS software (Apache http Server, Geo-server – Map server for the representation of geographic data and Pmapper as Web mapping framework). Moreover, it allows querying raster data to know sub-set values of different thematic maps simultaneously on a specific site, downloading the results of the structured queries in an easily and processable format.