Python Coding of Geospatial Processing in Web-based Mapping Applications

Python has powerful capabilities for coding elements of Web-based mapping applications. This paper highlights examples of analytical geospatial processing services that we have implemented for several Open Source-based development projects, including the Eastern Interconnection States' Planning Council (EISPC) Energy Zones Mapping Tool (http://eispctools.anl.gov), the Solar Energy Environmental Mapper (http://solarmapper.anl.gov), and the Eco- logical Risk Calculator (http://bogi.evs.anl.gov/erc/portal). We used common Open Source tools such as GeoServer, PostGIS, GeoExt, and OpenLayers for the basic Web-based portal, then added custom analytical tools to support more advanced functionality. The analytical processes were implemented as Web Processing Services (WPSs) running on PyWPS, a Python implementation of the Open Geospatial Consortium (OGC) WPS. For report tools, areas drawn by the user in the map interface are submitted to a service that utilizes the spatial extensions of PostGIS to generate buffers for use in querying and analyzing the underlying data. Python code then post-processes the results and outputs JavaScript Object Notation (JSON)-formatted data for rendering. We made use of PyWPS's integration with the Geographic Resources Analysis Support System (GRASS) to implement flexible, user-adjustable suitability models for several renewable energy generation technologies. In this paper, we provide details about the processing methods we used within these project examples. Index Terms—GIS, web-based mapping, PyWPS, PostGIS, GRASS, spatial modeling