< Previous | Next >

W-06: On-the-Fly Spatial Analysis With PostGIS and Google Earth

The Google/Yahoo/Microsoft interfaces that have vaulted web mapping into the mainstream have all too often been dismissed by GIS pros as being merely "lightweight" and "unsuitable for real work". But with open APIs, there are rich possibilities to integrate open-source back-end resources to provide robust "server GIS" functionality to complement the great usability of these platforms.

In this workshop, we'll link Google Earth to a PostGIS database and show how, using simple HTML forms and PHP scripting, you can put powerful spatial analysis tools in the hands of a general user audience that already digs the visually immersive experience of the interface. We'll build on the Network Links functionality of Google Earth that enables two-way communication between the interface and the spatial database. Next, we'll use the location information being "broadcast" by Google Earth to craft spatial SQL statements that, via PHP, we'll use to query the PostGIS database and use PHP again to convert the response back into KML on-the-fly. Finally, we'll mix in simple HTML forms to gather more user-specified criteria and enable them to perform spatial analysis tasks such as buffers, intersections and distance measures.

By the end of the session the student will have a solid grasp of the possibilities of using PostGIS on a server to transform "consumer" interfaces into powerful platforms for delivering spatial intelligence to a broad audience of general users.

User Level

Developer. Should have some familiarity with PostGIS, PHP, HTML, and KML.


As principal of The Timoney Group, Brian Timoney provides consulting services to clients ranging from petroleum companies to multinational humanitarian organizations. With a specialty in bringing spatial visualization to a general audience, whether through platforms such as Google Earth, Virtual Earth, or its own Flash-based thematic mapping interface, the Timoney Group has worked to integrate open-source server resources such as PostGIS and MapServer to complement the inherent usability of these web interfaces with robust data analysis. Brian is a proud member of FRUGOS the "Front Range Users of Geospatial Open Source".