Tags: Ajax, Google Earth Browser Plugin, grails, Information Visualization, KML, postgis, Rich Internet Applications, web mapping
Project Description: (You can read the spanish version of this article here)
VGICC is a Proof of concept using the new Google Earth Browser Plug-in. This application takes advantage of the plug-in to visualize and interact with statistical and geographical information of government contracts in Colombia.
(Note: The information available in this application is only for testing purposes. Official data can be found at the Official Contracting Site of Colombia, “PUC, Portal Único de Contratación” http://www.contratos.gov.co/puc/ )
- Launch Application (This application requires Google Earth’s Browser Plug-in. You can download it from this location:: http://code.google.com/apis/earth/)
- Screencast 1: 3D Visualization of contract statistics using Google Earth Browser Plug-in.
- Screencast 2: Browsing Contracts using VGICC
Provide an interactive Geographic Rich Internet Application that allows users to visually explore and discover new relations of Government’s investments using spatial, statistical and public contract information of Colombia.
This Geographic Rich Internet Application uses Interactive Web Mapping techniques as an alternative tool to explore PUC´s data. (Current search engine is based solely on plain text filters).
During development stages of this proof of concept some technical challenges must be confronted:
- Information Extraction:Although PUC (http://www.contratos.gov.co/puc/) lets public search options for general users, it doesn’t provide any free Web Service, RSS or interoperable API that could be integrated with external systems. However, thanks to the implementation of Web Scrapping techniques it was possible to automatically extract information from web pages published at PUC’s search portal.
- Transformation, Georreferencing and Data Loading: Once information extraction was accomplished, it was necessary to transform and georeference each one of the contracts against the available database of political-administrative divisions of Colombia. Furthermore, all data was stored in a geographic database managed by Postgres and Postgis.
Basically, the application allows geographic visualization of consolidated data by State and County. There are two basic interactions:
- State selection using lists: A user selects a State using a combo box and the application dynamically loads Kml data from the server side and shows the results using the Google Earth Browser Plug-in. Camera views are relocated according to the selected State.
- Contract search by feature selection on the map: A user can search a specific list of contracts related to a County. (State and County polygons are shown on the Google Earth Plug-in). Each balloon attached to a placemark on the map shows the amount of investment and quantity of contracts that take place in the given region and a link to the detailed list of contracts. Such list also provides links to detailed information for each contract as well as a reference to the official related site at http://www.contratos.gov.co/puc/.
Provide alternative ways of data discovery and exploration of PUC’s data (Portal Único de Contratación de Colombia) using techniques based on Rich Internet Applications, geographic information and 3D visualization.
- Google Earth Browser Plugin
- Java, Grails
- Postgresql, Postgis
Nevertheless the amazing features of Google Earth Browser plug-in, there are some issues related to rendering that affect visualization in some computers. For example, this is an extract of the correct visualization of the application for a particular State in Colombia:
In other machines polygons are not rendered correctly:
Or even in other machines rendering is completely different:
Such issue was reported at Google Groups. So far the issue stills open. (For more information look at Google Earth Browser Plugin: Polygons don’t render correctly )