Google Earth comparison

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This Google Earth comparison with World Wind is an attempt to show the differences and similarities between both products.

Contents

General discussion

A screenshot of World Wind using the halo and stars plug-ins.
A screenshot of World Wind using the halo and stars plug-ins.
A screenshot of Google Earth.
A screenshot of Google Earth.

Google Earth is a well-known 3D geography browser from Google, available for Macintosh, Windows, and (in beta) Linux. World Wind is an open-source 3D geography browser from NASA, available for Windows only (though a cross-platform version based on .NET and Java is planned for early 2007).

Both are sophisticated programs with amazing feature sets, and both have features that the other lacks but would benefit from. However, as similar as they are (or seem to be), Google Earth and World Wind are not entirely comparable because of significantly different focuses, development histories, and development philosophies. Many of us use both programs, depending on what we wish to accomplish. Each program has distinct advantages over the other, and so we will leave it to you to decide which you prefer (if you absolutely must have a favorite).

It is easy to construct a set of criteria by which either program appears superior to the other, but in reality they are two very different products aimed at different audiences. Google Earth uses commercial satellite imagery, and thus has much more data (and more recent data) available to users than World Wind. On the other hand, Google Earth lacks the Scientific Visualization Viewer capabilities of World Wind, and cannot be extended with user-authored add-ons. Moreover, World Wind provides direct access to the downloaded DDS and JPEG satellite images, and the open-source nature of the program guarantees that anyone can get the source code and 'roll their own' version of the program.

World Wind is totally free. It is also easy to use. No company limits what you can do with World Wind, and it won't cost you a dime. It includes a myriad of advanced functions and capabilities. For those, and for many other things, there is the world of Open Source. World Wind benefits from diverse input from a user community which has the power to shape its development. This has led to a proliferation of 'add-ons' and 'plug-ins' which are analogous to all those great extensions for Firefox. And this is only the beginning!

'Wait!', you protest, 'Google Earth has lots of stuff like that, too!' Yes, Google Earth has a whole lot of great user contributions, and this is one thing that makes Google Earth such an amazing program. Google itself owes much of its success to its policies of allowing users access to certain API's and allowing them to participate and play with things a lot. This has helped to stimulate new applications and rapid development of various technologies. Google is to be commended for their foresight and tradition of 'doing things a little differently.'

The Google KML becoming a de-facto Geographic Markup language is working to Worldwind's benefit since all the addons created for Google Earth can be slowly and transparently moved to Worldwind as the KML support develops.

But there is a significant difference between allowing developers and users to use a program within predefined parameters and what World Wind allows, which is total access to everything! In this area, and in others, World Wind will always be superior to similar products that aren't free and open-source, no matter how many features they might have and how high the quality of their imagery.

My advice? Use Both!

Cost

As well as the free version, there are additional versions of Google Earth available with different features. These versions start at $20 a year and quickly jump to $400 a year, with the Enterprise versions requiring contact from a sales person. Additional components for the $400 per year version cost $200 each.

NASA World Wind is only available free of charge.

Philosophy

World Wind is an education tool that allows users to explore many aspects of the Earth and Moon. With tools such as WMS and MODIS built in, World Wind allows viewing of recent world events, weather patterns, fires, and any other imagery people have desired to make available. The hope with World Wind is that people can get a better understanding and appreciation of the world around them.

Google Earth is not only a commercial product with the main intent of making money, it also is available in a free version, which is a platform for everyone to explore, find, and locate places around the world. With Google Earth you can find locations like restaurants, hotels, schools, museums, etc., and even your own location. It is more of a geographic search tool than a purely educational one. This isn't to say that Google doesn't want people to learn from their product, but that is not the main intent.

Terms of use

Google Earth Free is licensed for Home/Personal use. As such it cannot be used in a work environment, or at home where the results are work related. In fact, the way the license is worded, and if knowledge is considered a benefit, then you are in breach of contract and therefore breaking the law if you use Google Earth Free or Plus to find somewhere for your friends to buy a coffee, or tell them the distance between your house and theirs. Google Earth has been banned in several government agencies because of the terms of use.

NASA World Wind has very open terms of use. Basically anyone can use it, for any reason, from any location. Copyright of code and images still applies, but there is no restriction on using the application.

Feature Comparison

Different versions of Google Earth have different features. See the Google Earth comparison chart to see what is available in each version.

Planets & astronomical objects

World Wind covers Earth, Moon, Mars, Venus, Jupiter and Sloan Digital Sky Survey while Google Earth focuses on the Earth. Through add-ons it is possible to add additional worlds to World Wind.

Earth imagery

When installed Google Earth comes with one view of Earth. This view is made up of different photographs from different times and put together to look like one complete image. Google is attempting to keep this view as current and high detail as possible, giving you a good approximation of what the Earth currently looks like.

On the other hand, when World Wind is installed it comes with many views of the Earth (see World Wind Data Sources), each serving a different purpose, including Blue Marble which provides an overview of the Earth through the seasons, and Landsat which includes false color images of Earth.

World Wind has been built with the intention of having multiple views of Earth which one can look at separately, or blend together. Because of this design World Wind has better performance when compared to the free version of Google Earth when viewing external imagery such as the Blue Marble NG which is available for both programs.

With World Wind being free, individuals and organizations can use their own imagery to create new views of Earth in World Wind and not have to incur the initial cost of the more expensive versions of Google Earth.

There is no doubt that for getting a snap shot of the world as it currently is that Google Earth is more complete. After all, that's Google's intention and as a corporation Google can pay to have this imagery updated regularly and integrated into Google Earth. However, that doesn't mean that World Wind can't be used for the same purpose.

In addition to the community efforts such as the ZoomIt! and OneEarth projects, Microsoft has also allowed the World Wind community to integrate their Windows Live Local (formerly known as Virtual Earth) images into World Wind through the Virtual Earth add-on. This image set is in direct competition with Google's map service and should receive updates frequently.

Image Storage

World Wind allows you to set your own cache size and to change the location of the stored imagery. This allows you to share the same cache between multiple computers. This is beneficial in situations like schools where it would ease both internal network traffic and traffic out to the Internet. The images are also stored in a way that makes it possible to retrieve the individual image tiles from the cache.

Google Earth stores its imagery in a locked file of upto 2Gb in size. While it is possible to share the cache, its limited size reduces the benefit of doing so.

GPS Device

NASA World Wind has several plug-ins for GPS devices.

There is no official support for GPS devices in Google Earth Free. There are several 3rd party applications, however, that do allow basic GPS functionality. These are limited by the abilities of kml and vary in cost.

DTM display

Both Google Earth and WorldWind can display aerial photography or satellite imagery in 3D, using NASA SRTM data. The algorythm used for this is not the same, and a slight difference dan occur in the final result.

Users usually find that WorldWind is more accurate than Google Earth.

And WorldWind allows you to use your own more accurate DTM data.

You can find some examples here : [1]

Macintosh Version

Google Earth is now available for the Macintosh.

NASA is currently in heavy development on World Wind Java, which will run on Macintosh and Linux, as well as Windows.

Linux Version

Google Earth offers a (native) Linux version with its new Google Earth 4. As mentioned above, the cross-platorm World Wind Java is under development.

Download Size

As of January 2006 the download of Google Earth is currently 11.3 MB in size, the download for NASA World Wind is 54.1 MB.

There are several reasons why the World Wind download is so much larger than Google Earth. Firstly, Google Earth only has one initial view of Earth. World Wind comes with 43 different views of Earth and 3 of the Moon. World Wind has a very low resultion image of each of these views so that when you switch from one to the other there is very little delay before you see the changes. World Wind then downloads higher resolution tiles based on where you are looking.

Another reason why the World Wind download is larger is because it comes with all the placenames in the download. Even though World Wind has a lot more placenames than Google Earth they load faster in World Wind because they have already been downloaded. Also, you do not have to be online for a placename search to work in World Wind.

There are plans for future versions of World Wind to include the ability to download placenames as you look around the Earth. This will substantially reduce the initial download size. However, since add-on makers use this feature to add placenames to Earth (and other Worlds) the ability to create and search placenames without having to set up your own server will remain part of World Wind's features.

External links

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