Peel back the layers

Google Earth is more than just a fancy 3D map. Yes, you can use it to find your old house or plot a route from A to B, but that’s like driving a Ferrari at 30mph. To release Google Earth’s full potential, you need to tie in other sources of information. The key is the stack of palettes on the left-hand side, and particularly the one marked Layers.

US cities such as New York have the highest concentration of 3D buildings.

In Google Earth, a layer is essentially information that can be laid on top of the main 3D globe. It’s not just data from Google, either: the real power comes from third parties – companies, communities and individuals – adding their own data. Layers are sensibly grouped in an expandable tree view according to type, and by collapsing and expanding the branches of the tree you can switch whole groups or individual layers on or off. This is crucial, because while having too few layers means you’re missing out on important data, having too many results in information overload.

For clarity’s sake, we’re going to sort these layers into four basic types: fun, essential, interesting and foreign.

Fun layers Viewing the Alps or the Grand Canyon from satellite imagery hardly captures their full glory. You need the Terrain layer. This adds relief to the globe, so that the virtual landscape beneath the satellite imagery peaks and troughs according to the real-world terrain.

Similarly, cities look a whole lot better with the 3D Buildings layer. This adds flat-shaded models of the architecture in key urban areas (for example, downtown Tokyo or Manhattan) along with fully texture-mapped models of famous buildings.

Even more power is unveiled once you start using the 3D Warehouse layer. This overlays models developed by third parties and end users, which have been added to Google’s online model repository. You’ll need to download the 3D Warehouse Network link (http://earth.google.com/3d.html) and can even add your own buildings.

Essential layers

One of the layers we almost always switch on is Roads. It’s not just motorways and dual carriageways: you’ll find residential streets named and mapped out for even the smallest conurbations.

Or maybe you want to find a five-star hotel, Michelin restaurant or everything-under-a-tenner shoe shop? Then click on Lodging/Dining/Shopping Services and marvel as they appear before you, overlaid on the Google Earth map.

Google Earth is becoming an important social tool: the crisis in Darfur layer details atrocities in the Darfur region of Sudan.

Interesting layers

Possibly our favourite layer of all, the Geographic Web links to the best content produced by developers and end users in the Google Earth community. There are location-specific Wikipedia entries, photo content from Google’s photo-sharing service Panoramio and much more besides. Go on – click it!

Anyone with a social conscience will appreciate the Global Awareness layer. This boasts impressive presentations linked to environmental or humanitarian concerns, some of which – such as the crisis in Darfur – show just what you can do with Google Earth’s KML API.

Featured Contents has a more commercial feel to it, with a range of content from mainly US suppliers, including National Geographic and the American Institute of Architects. But click on Google Earth Community and you’ll get back to the real strength of Google Earth. Want to find out how packed the UK is with disused train stations? (Of course you do!) Or perhaps the locations of London’s fire stations, colleges and pubs? Then these user-generated layers are for you.