World Wind FAQ

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This is a list of frequently asked questions. If you have any questions please read this before asking in the Forums or Chat.

Pour les francophones : (lien vers la version française de la FAQ - link to the french version of the FAQ)


[edit] What is NASA World Wind anyway?

World Wind is open source Windows software that lets you zoom from satellite altitude into any place on Earth. Leveraging Landsat satellite imagery and Shuttle Radar Topography Mission data, World Wind lets you experience Earth terrain in visually rich 3D, just as if you were really there. See World Wind for more information.

[edit] Before Installing

Read System Requirements, Software Requirements, and Minimum configuration (just scroll down a page). World Wind is large and demanding of computer resources.

[edit] How can I download NASA World Wind?

The latest version is 1.4.0. See What's new in 1.4.

This version is clearly marked if you go to Help->About in World Wind.

To get the latest version visit NASA World Wind Download.

Alternatively you can run a more Windows Vista/7 friendly version of NASA World Wind 1.4 at (please note a browser plugin is required).

[edit] What about the source code?

The source code is for developers. It is an additional download to the Full Install. If you just want to use World Wind and look around, all you need is the Full Install.

If you want the source code as well, download both. Once you run the full install, copy the Data directory from your World Wind full install directory into your source directory.

See source code for more information.

[edit] System Requirements

  • Windows 2000, 2003, XP, Vista and 7 (see Windows Vista/7 compatibility section below)
  • 3D graphics card (see Video Card Compatibility)
  • Internet connection
  • Sorry, no support for Linux or Macintosh yet (but you may check multiplatform World Wind Java SDK)

[edit] Windows Vista/7 compatibility

WorldWind Properties Dialog Box 1
WorldWind Properties Dialog Box 1
WorldWind Properties Dialog Box 2
WorldWind Properties Dialog Box 2

World Wind was not designed for Windows Vista or Windows 7, but can run on it. The best way is installing World Wind outside of the program files directory, in C:\NASA for example, or on another partition (e.g. D:\Program Files\NASA).

Another workaround is to leave UAC enabled and run World Wind as an administrator:

  • Install World Wind as you would any other Windows program. Once installed then right click the World Wind application or shortcut and select "properties." (See Dialog Box 1)
  • On the properties dialog box under the Compatibility tab select "Run this program as an administrator" and then save this change. (See Dialog Box 2)

World Wind can then be run as any other Windows program and the UAC prompts whether to allow or cancel it.

You can also change WW directory properties and give users full access rights to it.

Disabling UAC is not recommended!

[edit] Spoon Solution

An alternative solution is to run the version of NASA World Wind. This version does not seem to have any of the UAC or Managed DirectX problems that the standard installer has, but be aware a browser plugin is required to use any apps. Run NASA World Wind online at

[edit] Windows 95,98,ME compatibility

Since these versions of Windows are no longer maintained by Microsoft, World Wind may introduce features that will break compatibility with them. As such, World Wind should no longer be expected to run on these systems. However, you may find that it will work as long as your system meets the other minimum requirements.

If you are using any of these systems and are having problems, feel free to ask questions in the Forums and Chat.

[edit] Software Requirements

The installer should detect and direct you to install these by default. If you are installing these because you believe there is an error, please install in the order listed below.

Microsoft .NET 2.0

Microsoft Managed Directx 9.0c (October 2005 redistributable)

[edit] Minimum configuration

With the minimum configuration, performance and functionality may be less than expected.

[edit] Recommended configuration

  • 1.4 GHz or higher CPU
  • 256 MB of RAM
  • DSL/cable connection or faster
  • 3 GB of disk space
Features such as atmosphere scattering and sun shading require additional CPU & GPU resources.

[edit] Installation

[edit] "Upgrading" from 1.3.5

If you have 1.3.5 you can move the old datafiles from cache to use it with version 1.4: From:

C:\Program Files\NASA\World Wind 1.3\Cache\


C:\Program Files\NASA\World Wind 1.4\Cache\

[edit] "Upgrading" from or earlier

There are several things to note when using the full install to upgrade to new versions from pre 1.3.2.

[edit] Blue Marble

The Blue Marble imagery has been removed from the installer in order to reduce the size of the initial download. The imagery will now download as you use World Wind.

If you have an old version of World Wind you can move the images to the new folder and you will not need to download them again. From:

  • 1.3.1 location: C:\Program Files\NASA\World Wind 1.3\Data\Earth\BlueMarbleTextures
  • 1.3.2 location: C:\Program Files\NASA\World Wind 1.3\Cache\Earth\Images\Blue Marble Tiled (1km per pixel)

C:\Program Files\NASA\World Wind 1.4\Cache\Blue Marble

Also move the base image:
C:\Program Files\NASA\World Wind 1.3\Data\Earth\BlueMarbleTextures\
C:\Program Files\NASA\World Wind 1.4\Cache\ImageUrls\\downloads\

[edit] Problems After a Successful Install

[edit] World Wind Fatal Error dialog box

If you get this error when World Wind loads try setting your display to either 16 or 32 bit color. There are reports that 24 or 32 bit color is causing this issue. 16 bit works without any issue. also check for graphic card compatibility.

[edit] My video card isn't working - "Unable to create the Direct3D m_Device3d" error

Check out the Video Card Compatibility list. Please, by all means, edit it depending on whether yours works.

Ensure that your video card drivers are up to date and Managed DirectX is installed.

Try going to Start->Run and typing 'dxdiag'. This should load up the DirectX Diagnosis program. Under Display please make sure everything is working and enabled.

[edit] Every time I try to run the program it crashes with a "JIT debugger" error message.

Yikes, these are the worst. A few notes when trying to debug these. The process ID and thread ID are pointless and don't really help at all. Any other error codes you might receive may be helpful. Do not be concerned that there was no debugger found. As we get more organized and get more of an idea what errors are coming up I will try to post additional information here.

If you get this error and want more detailed debugging information, you can start the World Wind application from the command line and redirect standard error to a file. This file will then contain the full text of the .NET exception and stack trace which may help in determining the cause of the problem. The following is a sample of launching World Wind to redirect standard error.

WorldWind.exe 2> error.log

Some people have reported that installing the software requirements listed above has fixed their issues.

A new DirectX Runtime can solve this problem:

[edit] My computer is crashing/hangs

Most likely you have a hardware/driver problem. Test your computer stability with 3D graphics by running for instance 3DMark or other DirectX benchmarking software.

[edit] Error x135

This error occurs when you try to run a .NET application but .NET is not installed (or is corrupt). To solve this error message, either install, or remove and reinstall .NET. See How Do I reinstall .Net?.

[edit] cordbg.exe !a 0x5b4 code

This is a compatibility problem with .Net. See How Do I reinstall .Net?.

[edit] How do I reinstall .Net?

  1. Uninstall all .Net.
  2. Delete in the Windows Directory and (maybe) in Program Files (directory).
  3. REBOOT.
  4. Start the World Wind install.
  5. It should ask to install .Net. Follow the instructions. (If you're not asked then you forget to delete something)
  6. REBOOT.
  7. Start the World Wind install again.
  8. It may ask to install DirectX runtime. Say "ok".
  9. Start the World Wind install again.
  10. Finished.

[edit] More Debugging Help

This blog post points to several verification tools to make sure .NET is installed properly.

[edit] No Landsat icons / No Images in Layer Manager

If you are missing your "Images" or "ZoomIt!" choices in the Layer Manager. Check to make sure World Wind can connect to the Internet. These are downloaded when you start World Wind. Most likely cause is a proxy or firewall blocking World Wind. (see also Issues Downloading Tiles)

This can also happen on Windows Vista - see Vista compatibility section.

[edit] Issues Downloading Tiles

To make sure there is no server-side problem check Server status page.

[edit] Download Monitor

Download progress monitor window showing detailed information about requested files
Download progress monitor window showing detailed information about requested files

World Wind version 1.3 has a download monitor which can be very helpful diagnosing problems. Hold down Control (Ctrl) and hit H.

[edit] Why am I getting 'Problem connecting to server. Trying again in 2 minutes'

Several possible reasons:

  1. Maybe the server is down. You could say... try again in 2 minutes.
  2. You may be behind a blocking proxy/firewall. You'll need to configure a port remapper, or hunt down an admin to help. See below.
  3. Make sure you have installed [1]. (Issue WW-6)
  4. You could be in a country that blocks access to worldwind sites & download servers. Try to find a proxy? We haven't yet had any confirmed reports of this.
  5. Remember to use the HTTP Download Monitor (CTRL+H) to see what exactly is going on. Double click an entry and you get a box. Paste the contents of that box into a new forum thread in the technical support section and someone will come along and help you.

[edit] Is there a way to set a proxy?

Press Alt+Q to edit the proxy settings. The default setting is to use the Windows default proxy settings.

[edit] Proxy Issues

If using the proxy settings in World Wind doesn't work you may want to try using a portmapper such as AnalogX PortMapper.

[edit] Why are the wrong image tiles showing up?

It is possible that you are viewing more than one layer and therefore are not seeing the tile you expect. Go to the Layer Manager and make sure only one image layer box is checked.

If you still believe that the tile contains bad data you can hit F5 to refresh the current view. This will redownload all visible tiles for all active layers. Alternatively, follow the instructions for "How are the tiles named?" to delete the individual tile.

If you do manage to find a "bad" tile and keep downloading the same "bad" tile, please kindly record the filename information of the tile and let someone know in Chat or on the Forums.

[edit] How are the tiles named?

The tile-naming structure is based on the layer name, level, longitude and latitude. [2]

Starting with World Wind 1.3.3 you can view tile name information from within World Wind.

To view tile filenames and outlines open the Layer Manager and right-click on any bottom level image node (an item without an arrow) and select Properties. In the resulting window change the RenderTileFileNames property value to True and you will see the red outline and text for each tile.

Be aware that the text and outlines are rendered at a different height to the terrain; for best results set the Vertical Exaggeration to 0 and make sure you're viewing the center of the outline.

[edit] Imagery related questions and tips

[edit] The questions we get every day

[edit] Aah! I zoom in and it's all blurry! Help!

If you're looking in the United States and it's blurry please read Why can't I see my house/car/etc?.

If you're looking outside the United States please read Can I use this for non-US locations?.

[edit] Why can't I see my house/car/etc?

USGS Imagery of Washington, D.C.
USGS Imagery of Washington, D.C.

AKA Why am I not getting pictures like this --->

That is the USGS Urban Area Imagery. USGS Urban is about .25m/pixel and only covers certain areas in the United States. These are the color images you may have seen. You can generally see cars with this layer. Note that it is only available for select cities, if you are not looking at the right place the images will be white. A list of available cities can be found at USGS Urban Areas.

Alternatively you can use the USGS 1m / topography which covers most of the United States, but is in black and white color. You can see most buildings and roads. You can probably find your house.

More information below.

[edit] Can I use this for non-US locations?

The United States Geological Survey (USGS) has high resolution data available only for the United States. However, the Landsat data is available globally.

The Landsat imagery has a lot less resolution than the USGS Ortho imagery. However, if you still don't believe the resolution is as good as it should be, click the sample images in Landsat and compare your results. If the images are of different quality it may be a downloading issue - see Issues Downloading Tiles.

While there is high resolution imagery for many other locations, most of this imagery is licensed and is not freely available. If you know of any public domain or unrestricted datasets that we can incorporate please feel free to tell us about it.

The OneEarth add-on is an attempt make use of public WMS servers for providing high resolution imagery. Several countries have data available.
You can also try Virtual Earth plugin which has hi-res data for some countries (UK, Italy, Australia, Japan).

We encourage all users to contact their local politicians about releasing GIS data for all to use.

Pivot Irrigation
Pivot Irrigation

[edit] What are these crazy circles?

These are crop fields watered by a method called central pivot irrigation. The forum has more discussion on the topic.

[edit] When was this imagery photographed?

That depends on the layer. The NLT Landsat, OnEarth Landsat and Geocover are from 1999 to 2003, with 2000 being the most active year. The Geocover 1990 was taken between 1987 and 1993. The USGS 1m Digital Ortho varies more. It was taken from 1990 to 2000. Search for a US location through TerraServer® and look for the USGS entry. The USGS Topo maps vary from within the past few years to several decades ago. Streets and building locations in particular may be quite out of date. USGS Urban Area Ortho dates from 2001 to 2004 and some areas are still being photographed and you can see the dataset ages at the USGS site.

[edit] Can I see the world in real-time?

This just isn't practical and won't be possible anytime soon. To do this requires a network of satellites dedicated to covering the earth. Just to provide as much detail as the base layers World Wind loads first, the camera resolution on each one has to total about 100 megapixels. Perhaps the military has such a network, but it is certainly off-limits to anyone else. The images have to be received on the ground and processed. Then they all have to be combined where they overlap and corrected for the distortion caused by the earth's curvature. Finally after compressing the imagery from gigabytes down to several hundred megabytes, a server has to send it out to everyone. This requires an enormous amount of bandwidth for the server. Even if that weren't a problem, the internet connection for the majority of high-speed users is still too slow for more than about one update every hour.

But you can see near real-time imagery: Global Clouds, NRL Weather, MODIS are all 3 hours to less than a day old.

[edit] Landsat

[edit] With the new Landsat, what's with the colors? Why isn't my area covered?

NLT Landsat 7 button
NLT Landsat 7 button

The NLT Landsat was created with the intent to have more realistic coloring. The NLT dataset is not as high quality as the original ("OnEarth" or "Geocover") Landsat datasets are. However, most areas should be covered at 30 meter resolution.

See NLT Landsat Processing Techniques for information on how it was processed. And NLT Data Issues for information on issues in the imagery.

[edit] USGS

[edit] How do I load the .25 meter resolution maps, as shown in the screenshot of D.C. on this web site?

USGS Urban button
USGS Urban button

You can access these images by either selecting Layer Manager->Images->USGS Urban Area Ortho, or clicking the USGS Urban button.

[edit] All I see is white tiles when viewing the USGS Urban data!

USGS urban data is not available for all areas. If you aren't looking in the right place (in one of the cities listed at the Terraserver website or on the Urban Area list), you'll see whitish green, and nothing else. The Urban Layer Highlighter is extremely helpful locating areas.

[edit] How to make use of the USGS layers

USGS is the acronym for U.S. Geological Survey. In other words, the data that is available in the USGS layers is only for the USA. While it is possible that similar data is available for other parts of the world, most of it is not freely available, and therefore is not incorporated into World Wind. See Using the USGS Layers for step-by-step illustrated instructions.

[edit] SRTM

[edit] Why does <insert mountain or other relief feature> not look like it should?


There are several possible reasons. If the area is completely flat, then you are looking at an area above or below 60° latitude, where there is no elevation data due to the fact that the satellite that took the measurements orbited more or less around the equator, and above 60° the angle at which the measurements were taken was too extreme to get decent data.

If this is not the case, it is most likely due to the fact that the elevation data, SRTM, is taken much like a bat's echolocation or sonar measurements - the elevation is "sounded" from a satellite. Unfortunately, these "soundings" are only taken about every 90 meters. As a result, mountains and such may look strange. Imagine the satellite collects elevation points in a grid. So it flies over the Alps where two peaks are 50 meters apart. It takes one reading, say, 40 meters away from one peak's top, but manages to hit the highest point of a different peak right on the top. It never hits the first peak's tippy top.

Referring to the illustration, say the vertical blue lines are measurements taken. The red line will be what Worldwind shows, grey being the actual landscape. The left peak shows as being higher in WW, but the right one is actually the highest.

In addition to the above problem, for some areas of very high relief, no soundings were obtainable, so SRTM derived data for these areas is not at all accurate. However, in 2006, both World Wind and Google Earth installed improvements to the elevation data, using data from other sources, which have created much more accurate 3D views of thousands of mountains, including Matterhorn and Everest.

Cities are a variation of the mountain problem - since the "soundings" are taken in a grid, and the elevation varies so much in cities with skyscrapers, the "mountainous spikes" effect is produced. One sounding will hit a skyscraper, the next might hit a car, and the next might hit a 3-story building. As a result, the elevation in cities with skyscrapers and other tall buildings looks like a big field of randomly placed spikes. If you are looking at a city, the easiest way to resolve this is to turn off elevation by simply pressing the 0 key.

In addition, some surfaces look bumpy that shouldn't be, such as airplane runways. This is caused by different materials and ground coverings giving false readings because of the way they reflect the radar. For more on the method used to collect the data, see the JPL Website.

[edit] Google Earth

[edit] Which is better, Google Earth or World Wind?

Both NASA World Wind and Google Earth are sophisticated programs with amazing feature sets, and they both have features that the other would benefit from. Despite how similar both programs seem they are not entirely comparable due to significantly different focuses, development history and philosophies. Many people use both programs depending on what they wish to accomplish.

See Google Earth comparison for more information.

[edit] Cache and data related questions

[edit] Can you make the amount of cache adjustable?

Press ALT+Q to bring up a dialog box where you can change this setting.

[edit] Can I copy my cache data to another computer?

Yes you can. Click here for discussion.

[edit] Can I use my 1.2e cache in 1.3?

Yes you can. See: Converting 1.2e Cache for use in 1.3

[edit] How large is the data set? Is it available for download?

Collectively the data sets are around 4.6 Terabytes. As such they are not available as a full package for localized download. There are, however, several data sets available for download as cache packs.

[edit] How about bittorrent for the data sets?

Because of the size of the data used, and the limited amount of data users download of the total available data, it is unlikely that p2p would make much of a dent in the problem of serving that data.

But see above.

[edit] Known Issues

[edit] Is there a way to narrow down a search for a place?

We realized this problem almost immediately (there are approximately 2 million places with 3 million more about to be imported) and we're going to associate a "Place" with a country or geographic identity. Perhaps you will type in "Paris France" and you will only get matches that have those two keywords. Also, if anyone hasn't noticed, the searching tool is case sensitive, and that will of course be changed as well.

In addition, we want to display more meta-data information about a particular place, such as the type of place (mountain, populated place, beach...), and perhaps attributes such as population or elevation. We of course are open to suggestions that anyone else might have in terms of what would be useful.

Several people are working on placenames right now. Stay tuned.

[edit] There are place names all over the place!

Yes, the number of placenames is a bit of a nuisance, and we're working on ways to remedy this problem. We still want those placenames in there — we just don't want them to take up so much real estate on the screen.

Side note: if you go to the layer manager (viewlayer manager) under placenames, you can click off certain ones. It may be helpful to remove the one labeled "US Anthropogenic Features" which contains info about churches, schools and other landmarks in the US.

[edit] The entire time the application is running, it uses 50-100% of the CPU, why?

World Wind was not coded for performance, sadly. At least, you can rest assured that this problem is very common and most users experience it - there is nothing wrong with your computers. This will get optimized in future releases, but we're still heavily in the Research & Development stage.

Also there are a few bugs attributed to high CPU usage. Check out: [3]

[edit] World Wind startup/shutdown takes a lot of time

If you encounter problems with World Wind taking several minutes to load and just as long to finish closing, and your World.xml file located in %appdata%\NASA\World Wind\ is bigger than several KB, then you probably disabled (set to 'false') UseDefaultLayerStates option. This option is supposed to let WW remember all of the layer states upon restart. (This includes every item, not just which layers. For example, completely expand all of the branches of the boundaries layer and you'll see many, many, many *.wwb entries. Each of these gets an entry in World.xml)

The cached entries may not be cleared by turning this setting off/on. Just delete World.xml.

WorldWind.log can grow into a monster as well, so delete it, too.

The next time WW is started it will recreate the file with the default settings. Change the program settings (options, autoload plugins, etc.) to the way you want them to be, but don't turn on any layers. Then exit WW and back up World.xml to another location. You can use this to overwrite the file if things go bad in the future and not have to reset your options each time.

[edit] Borders are in the wrong place, fix them!

The data to build the original borders was correct data for when it was gathered. Some areas have since become outdated. As basic as country borders might seem, it's actually been very hard finding good and updated data. If someone has a source for updated borders, it can be integrated into World Wind, but because of priorities there is much more to improve first. Since this is an open source project, users are encouraged to help fix borders and submit them.

[edit] Tips

[edit] How can I extract data from Worldwind for use in other modeling and mapping applications?

All the data is cached in the installation folder under the "Cache" directory. It's organized by the dataset. (See also: How are the tiles named?)

You may have more luck reading up about the WMS protocol, and then interfacing with the same servers that WW connects to.

[edit] Are images on World Wind copyrighted?

The Landsat Global Mosaic (except for i-3 visible layer), Blue Marble, and the USGS raster maps and images are all Public Domain. See Copyright Questions When Using Images From World Wind for more info.

[edit] Can I use images on World Wind for commercial purposes?

Most of the datasets that World Wind has access to are in the 'Public Domain' and can be used for commercial purposes (but generally not the actual data servers), however, some datasets, including 3rd-party add-ons/plugins may have their own terms-of-use which could prohibit commercial use of their products and services.

[edit] What is the most proportionate "vertical exaggeration"?

Although it seems that 2 or 3 should be the "correct" vertical exaggeration, "1" is the correct and real vertical exaggeration. More correctly, "1" means that the vertical height is multiplied by 1.0, whereas vertical exaggeration of 3 means that vertical height is multiplied by 3.0.

[edit] Secret Keys

There are no secret keys. See keyboard actions for a full list of available actions. (Actually there are but if we told you then ... well... they wouldn't be secret would they?)

[edit] What happened to the measure tool?

For the story and a replacement tool see the Planimetric Measure Tool plugin.

[edit] Default Layers - Can I make the I3 ESAT the default Landsat7 Imagery Layer?

Yes, in the preferences, disable UseDefaultLayerStates. If you want to get your hands dirty, you can also edit and rename @Images.tmp to @Images.xml

[edit] Future Versions

[edit] When will the next version be out?

When it is done... Check the Road Map for information on future versions.

[edit] How about other planets?

There are several worlds available in World Wind. The Earth, Moon, Mars, Venus and Jupiter are included and more can be added through add-ons.

[edit] Stars?

Stars have been added to World Wind through the Stars3D and Stars plugins.

Also check SDSS.

[edit] Do you think you could add boundaries of other sub-national entities, such as Swiss cantons, Australian states, and Canadian provinces and territories?

Boundaries for the Canadian provinces and territories are now included.

For other countries see: Additional Boundaries, Country Boundaries Set, DYNAGIS Boundaries

[edit] I would love to see a feature that showed day/night in realtime say taken from the USNO atomic clock. Perhaps a setting where you could follow the terminator and such.

This feature was added in version 1.4

[edit] Will there be an option to export animations/movies in the future?

Windows Media encoder allows screen capturing (all or selected area) and converts to .wmv video. This works very well but does require a substantial amount of video memory and CPU usage.

The encoder can be downloaded for free here

Another option is the Movie Recorder plug-in which takes a camera script and saves screenshots to disk.

You can also use Fraps: that records realtime video from 3D applications. A similar example is CamStudio, at, which records to AVI or SWF.

[edit] Developers

[edit] What license is World Wind released under?

Nasa Open Source license v1.3.

In particular, this license is more of the LGPL variety, not requiring that modifications are redistributed. Here is a relevant section from the license.

I. A Recipient may create a Larger Work by combining Subject Software with separate software 
not governed by the terms of this agreement and distribute the Larger Work as a single product. 
In such case, the Recipient must make sure Subject Software, or portions thereof, included 
in the Larger Work is subject to this Agreement.

See also NOSA page with short explanaton of the allowed and non-allowed WW uses.

[edit] Will World Wind remain always free?

In short, yes. It's a government funded program and as such cannot be charged for (other than through federal taxes).


The program itself is open-source and will always be free. Access to NASA provided data will also remain free. However, there might be private companies that want to provide their data through World Wind (perhaps magazines or encyclopedias) and perhaps might charge a fee for access to their data. As long as there are people who want NASA provided data, and are using World Wind for that purpose, it gives the departments in charge of providing data a reason to ask for more funding to improve bandwidth to the data.

[edit] Is World Wind truly free?

Yes, it is. You don't pay for it. You can run it, you can view the code, you can modify the code and you can redistribute your modified version.

Some do not agree and say that according to Free Software Foundation the NOSA license (which is one of the OSI approved licences) is not free. The fact is that FSF uses its own definition of this word, but it can't claim that this definition is the one and only and all others are wrong. FSF has no trademark on the words free or free software, FSF should approach the NOSA team if they wish the license changed.

None of the developers has ever complained about NOSA limiting their freedom.

[edit] Why did you decide on C# and DirectX?

See this forum posting: [4]

[edit] Mac and Linux ports?

Since this is open-source, we encourage any OSX or GNU/Linux programmers to start a port and we will try our best to provide whatever resources we can towards the effort. There are some community resources at porting World Wind.

World Wind Java SDK is cross platform. (For more information see the Java section.)

[edit] In what areas do you need the most help? How can I contribute?

Check the How to Get Involved page to see how you can help with the World Wind project.

[edit] Copyrights

Copyright Questions When Using Images From World Wind

[edit] Links

[edit] What data does World Wind use and where can I access it?

World Wind Data Sources

[edit] Where can I find more links?

Please see the World Wind forums

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