Visualizing large geospatial datasets with KML Regions

Regions are a powerful KML feature that helps viewing very large datasets in Google Earth without sacrificing performance. Data is loaded and drawn only when it falls within the user's view and occupies a certain portion of the screen. Using Regions, it is possible to supply separate levels of detail for the data, so that fine details are loaded only when the data fills a portion of the screen that is large enough for the details to be visible. It becomes easy to create compelling interactive presentations of geospatial datasets that are meaningful at both large and small scale. We present two example datasets: worldwide past, present and future carbon dioxide emissions by power plants provided by Carbon Monitoring for Action, Center for Global Development (http://carma.org), as well as 2007 US bridge safety ratings from Federal Highway Administration (http://www.fhwa.dot.gov/BRIDGE/nbi/ascii.cfm).