Web GIS Solutions using Open Source Geospatial Software

The talk held by Karsten Vennemann at the 2008 WAURISA Conference in Seattle gave an overview on building web GIS solutions using open source geospatial software components. A selection of the most advanced and popular open source components, their roles and functionalities in an application framework are described. A complete stack for building web GIS solutions can include a client-server application framework, a web mapping engine supporting cartographic rendering functionality and basic GIS capabilities, data storage solutions such as spatial databases, and additional tools extending or enhancing the basic GIS capabilities of the mapping engine. The concept of an interoperable software solution is illustrated by a variety of examples. Web GIS application frameworks are either complete client-server solutions such as MapFish and Mapbender or Web GIS clients such as Open Layers and Ka-Map. Internet mapping engines such as MapServer and GeoServer render images, provide basic GIS functionality and/or provide the functionality for serving Web mapping services (WMS) and Web feature Services (WFS). Using cached and tiled data in a web GIS application can substantially speed up its response time. TileCache is a server and caching solution that can be used for the creation of cached data from WMS. Feature Server provides data conversion of simple features from a variety of input formats into target formats such as GeoJSON and KML and can be used to integrate the framework with additional applications. Spatial databases include solutions such as PostGIS and MySQL. PostGIS itself provides comprehensive GIS capabilities that can greatly extend the mapping engine’s capabilities and simplify execution of geo-processing tasks using spatial SQL. Additional tools can be integrated with the framework to provide specific GIS capabilities. One example for such a tool is the Perl module GeoCoderUS that can provide geocoding for the entire US based on census Tiger Line files.
Download the presentation slides here.

Terra GIS presents online list matching tool at the WA URISA Conference

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The WA URISA Conference was held April 23-25th, 2007 in
Lynnwood, WA. Karsten Vennemann gave a technical talk about the member list matching tool: “Building an online tool for spatial joins using open source software“. The following is the Abstract:

Most commercial GIS desktop software includes tools to spatially join information to a location. A spatial join operation adds information based on the geographical location of one feature to another. This talk illustrates how to build an online tool that can perform spatial joins using open source software. The technical solution presented can support any type of spatial join based on street address and a polygon layer and can be run on both Windows and Linux server platforms. For simplicity we will focus on providing a technical overview on how a web based tool can allow users with little or no GIS knowledge to attach legal district information for Washington State to their membership lists. The work order for the tool can be broken up into four main parts: 1) file upload to the server, 2) the retrieval and geocoding of the address records, 3) spatially matching the legal district information, and 4) the transfer of the information to the client computer. In step 1, the user uploads a text or Excel file via web interface onto the server. In step 2, the address records are read, and their geographic location (latitude/longitude) is determined by geocoding them against the 2006 Tiger line data of the US Census Bureau using PHP and Perl. In step 3, the legal district for each record is then spatially found running an SQL query against a PostGIS database. Finally, the tool streams the results to the client computer in form of a text or MS Excel file.

For more information about this tool please contact us. You can download the presentation slides here.