How accurate is Google Earth data? A review of Google Earth for Mac

Having had a few weeks to play with Google Earth for the Mac I have finally gotten down to writing a brief review of the features. While some of the features are undoubtedly cool, the thing I was most surprised by was the poor quality of the data layers. Read the full review after the jump.

Much has been made in the popular media about the groundbreaking Google Earth, its cool fly-overs and aerial photos, and its ability to support all types of mash-ups. While the Windows community has had Google Earth since late Summer, the Mac community has just finally gotten our hands on it. Although I am ambidextrous when it comes to computers and have used Google Earth for months, it was not until it came to the Mac, my favored OS, that I really sat down to do a thorough review. The review covers three main areas, Overall use, Analysis features, and Data layers.

Overall Use

Google Earth, while lauded by some pundits as a do-it-all mapping service is at its heart an easy-to-use, good-looking address look-up service. Looking up addresses and getting directions was easy, and accurate. Although I didn't compare it to other services in terms of routing as other reviews have done, I found the routes to be accurate and well planned. Navigation, zooming, tilting, and panning all worked flawlessly adding to the nice experience of looking up addresses. Overall, I had no real complaints about the use of Google Earth, however, I also had no real standout features either. While the service works well, there is nothing inherent about it that begs me to use it for anything other than finding an address or getting directions.

Analysis Features

As a power user of GIS, I have to say that I am sorely unimpressed by the analysis features, or lack there of, within Google Earth. To be fair, the purpose of Google earth is not to replace a GIS nor is it to do analysis. Rather, as stated above, Google Earth is an address lookup and directions service and any analysis you get with it should be considered a nice bonus. In fact the only real analysis feature contained within Google Earth is the measure tool which allows a user to measure a straight line distance between two locations. Beyond this, analysis is left to the more advanced versions of Google Earth. Again, to be fair this system is not about conducting analysis, but rather looking up addresses and finding directions.

Data Layers

The last part of the review, and the part that is crucial to the success of a service like Google Earth, is a look at the data layers. Google Earth comes with a wealth of different data layers that can be turned on and off by the user and are designed to significantly enhance the user experience. Importantly, it is these layers that have received a great deal of the publicity in the media because they allow the user to easily find businesses, restaurants, banks, gas stations, etc.. near addresses they are looking up. Thus, a key aspect of the success of Google Earth lies in the accuracy of these data layers. Unfortunately, when I typed in my home address and began turning on layers I was instantly surprised by the overall poor quality of the data layers. In order to check the accuracy of the data layers I turned on all of the layers and compared all the results within 3/4 of a mile from my house with current locations. What I found was less than good:

Neighborhood Shopping Area 1
Of 6 addresses that were displayed only 2 were still in business, 3 were closed (each for over two years) and 1 was over 1.7 miles off from its true location.
Neighborhood Shopping Area 2
Of the 12 businesses and restaurants in the area 9 are correct and three are incorrect. One of the incorrect addresses is a business that has been closed for over 4 years and is listed at the same address as a Starbucks that has taken over its location. The other 2 incorrect addresses are restaurants that have been closed or moved for over two years.
Mythical Shopping Area 1
Most surprising of the errors was the mythical shopping area that contained a Chocolate shop, a Subway and two Rite Aids. Importantly, none of these exist, nor have there ever been any shops on this residential street.
Mythical Shopping Area 2
A pantry market was shown as being across from my home, when in reality it is located approximately 1.26 miles away. Interestingly, this is the home address of the former owner of the market, a business he sold over two years ago.

What is potentially most disturbing about these inaccuracies is that this neighborhood is a historical neighborhood (many houses over 75 years old) within a city of over 250,000 population, not a rural area or a fast growing suburban neighborhood. If I were Google, I would be having talks with my data provider Teleatlas about why there are so many problems. While this is admittedly a small sample of addresses contained within the Google Earth database, it is a random and presumably representative sample of the data layers. With this in mind the data is very troubling and potentially very misleading. I encourage others to check the accuracy of the data in locations they now well in order to determine if the results of this very small study are representative of a larger issue with the layer data provided by Google earth. In a nutshell, if I were in a city i didn't know and was using these data layers to find restaurants and services I would have been very lost and very mad.

Conclusion

Overall, Google Earth is a fine service for looking up addresses and finding directions, however there appears to be serious problems with some of the data layers that are available. With this in mind, I would be wary of using Google Earth to design vacations or find restaurants and businesses in places I didn't know well.