Google is the giant, the big G, of course. And the data and resources it can muster are always tremendously impressive. Google Earth on the PC or Mac is a sprawling mash-up between satellite imagery and Geographical Information System (GIS). But how much of its functionality has made it onto the iPhone? After all, Google Maps already has satellite imagery, doesn’t it? Why bother with Google Earth?

Good question. It’s currently little more than a novelty. However, it’s free, it has a unique ‘wow’ feature built-in and it’s likely to get better in the future

The ‘wow’ bit comes from the tie-in to the iPhone’s accelerometer. When you first zoom into your current location (or to any other spot in the world), the satellite imagery looks identical to that in Google Maps, built-into the iPhone OS. However, swing your iPhone (or iPod Touch) up so that its back is facing the horizon (as if you were looking through it onto the world) and Google Earth’s view will change as well, showing a pseudo-3D simulation. It’s ‘pseudo’, of course, because 99.99% of the world is only represented as a 2D image and all the application is doing is tilting and scaling the image to fool your eyes into thinking you’re looking at 3D terrain.

Having brought up this ‘3D’ view, you can drag the scenery with your finger to simulate ‘flying over’ the landscape, but if you really want to impress your friends, go to part of the 0.01% of the world that is mapped in real 3D, i.e. with terrain data. For example, search for the ‘Grand Canyon’ and then tilt your iPhone. It’s a lot cheaper than renting a helicopter…

Alas, the sheer amount of data involved and the relatively slow processor in the iPhone means that there are waits sometimes, especially after tilting up to get into 3D view, while new data and scenery is identified, downloaded and then rendered. But, with a little patience, it’s worth it in the end. Current ‘layers’ of data available are ‘Wikipedia’ (for articles) and ‘Panoramio’ (for photos) – just tap on the icons to be shown the item directly. More layers will doubtless be added in the future, but the biggest improvement Google could make to this application would be to improve its startup time. There’s currently a twenty second wait while Google Earth loads and then displays its ‘zoom in’ animation to the last spot you browsed. When all you’ve done in the meantime is switch away to send a text message, for example, this delay is rather annoying.