Wednesday, September 15, 2010

10 Myth Busting Facts about Google Earth

Back from my trip to America now, whilst out there I met up with colleagues who also train teachers and students in using GEarth. Over beers a topic that often came up was misconceptions about Google Earth from those with no GIS or Google Earth experience, so I've put together my personal list of myth busting facts. They're in rough descending order of importance:

1] You can make your own map in GEarth. You can add points, lines or areas to Google Earth marking anything you want. Tutorial.

2] Google Earth isn't just satellite images and roads. There are lots of sets of data (called 'layers' because they are like a layer of see through plastic that can be turned on or off at will) you can look at draped over the background imagery of Google Earth. Examples include ; weather, Panoramio photos and shipwreck locations (Layers > Ocean > Shipwrecks) . Some of these layers come on automatically when you use Google Earth, you can turn layers on or off in the layers column as you wish. To cut down screen clutter I usually turn everything off apart from terrain.

3] Any map you make in Google Earth is not visible to anyone else unless you publish it. Just because you write a document in Microsoft Word it doesn't mean Microsoft can see it, it's exactly the same with anything you create in Google Earth. Background elements such as satellite images, roads and town names provided by Google are visible to all but add elements to Google Earth yourself and only you can see them.

4] You can publish your own map without going through Google. The layers column (bottom left of the screen in Google Earth) is a selection of materials that Google think lots of people will find useful but if you want to publish your own map by emailing it to people, or putting it on your web page you can just do it without checking with Google first.

5] The satellite data in Google Earth is historic, i.e. its not imagery taken today. Usually its a pretty recent image taken in the last 3 years.

6] Google does not censor satellite imagery. I can't say this for certain but stories appearing about Google censorship in the press are usually a misunderstanding based on age of imagery or the fact that Google buys a lot of its images from other agencies who may be doing the censorship themselves. See this post for details.

7] You can use Google Earth offline. Google Earth stores the satellite images of areas you visit on your hard drive in a special folder called a cache. If you've visited London in Google Earth you can then disconnect from the web and use Google Earth to look at London some more. Google Earth will do this by loading the images back in from the cache. If you then fly to Paris and zoom in Google Earth will just show you a fuzzy mess because it can't download the new imagery to produce Paris on screen until you connect up to the web again. This is very useful for presentations using Google Earth at conferences where you can't rely on wifi.

8] You can tilt the view to see mountains in 3D. A couple of years ago it was a common misconception that Google Earth was just 2D, many users didn't know you couldn't tilt the camera view and see the landscape in 3D. I'm not sure its such a common misunderstanding any more.

How To: tick the terrain layer in the layers column if you can see one, if you can't, don't worry. Hold the shift key down and use the up and down arrows on your keyboard to tilt .

9] Google Earth is not a security threat. Lots of scare stories have gone around about terrorists using Google Earth to plan attacks or thieves using it to set up robberies and that Google Earth should therefore be turned off or censored (see 6 above). It may be true that Google Earth is a tool for enemies of society but there are two main arguments against censoring Google Earth; firstly, satellite imagery has been available for sale to all comers for years before the appearance of Google Earth - if your security system relies on people not being able to see dated satellite imagery of your house, military instillation or city then it's never been very good security. Secondly, cars, mobile phones and pens are all used by terrorists and thieves, are we going to ban them too?

10] You can use Google Earth to explore other Planets, the Sky and History. Google Earth has lots of other features people users are usually unaware of, for example, you can use it to explore the surface of Mars, the Moon and the night sky. It also can be used to show historic imagery.


Anonymous said...

I don't think #7 is true, at least for versions past 5.0. see here:

However if I'm wrong and they have reinstated offline mode that would be great!

Rich Treves said...

That blog post you link to describes how to get data to a computer which is permanently offline. Its certainly complex. As I describe, if you have a laptop (or any computer) that is *intermittently* connected to the web then you can fill the cache with data and access that data offline. Try it!

Brad said...

Most people don't know that much of the "Satellite" imagery is actually taken by aircraft flying at 800-1500 feet.

Drew Kesler said...

Awesome points! I've been working with Google Earth in my company in the Oil Industry for a couple years now, and your facts nailed the concerns people have voiced to me. Good work!

Ian Turton said...

Re: Google Earth Censorship

I remember talking to Michael Jones a while back regarding imagery - it was during the Israel/Lebanon conflict when Google had access to high resolution imagery of the war damage but could only publish the Lebanon side of the border as US law prevents the release of high resolution imagery of Israel.

I can't recall how they finally resolved it but they were thinking hard about what to do - They didn't want to be accused of being anti-Israeli by only showing damage in Lebanon or being pro-Israeli by not showing any damage.

Rich Treves said...


Good one. I was trying to think of one about imagery resolution varying but it isn't really a misconception. I think you've nailed the point well in that comment.


Chris said...

Actually all photographs are satellite photos with an apparent height of 800-1500 feet (using a camera lens). If Google or TerraMetrics or GeoEye were to fly aircraft at that height (below small airport pattern altitude) it would take years just to photograph a state like Pennsylvania. Not to mention that in cities you would likely have terror alerts as low-flying aircraft made repeated passes over highly populated areas.

Anonymous said...

Hi Brad,

I'm sorry but you are not correct. The link you posted does not specify that aircraft flying above at 800-1500 feet take the images. In fact it says that the satellite imagery provides a view of the Earth from that altitude. If you browse Digital Globe, GeoEye data repositories you would see that the images are taken by satellites such as WorldView 1,2 and so forth. The images taken from these satellites provide a clear picture at the aforementioned altitudes above the surface.

Rich Treves said...

Didn't know that. Incredible accuracy...

Muki Shan said...

Hi ! Is it possible to know from what height we are observing an image at a particular zoom level ?