NASA World Wind FAQ’s
To understand the technique “Sounding” in NASA world wind, just imagine, that the satellite collects elevation data in the form of a grid. Therefore, it flies over the places like Alps, where two mountain peaks can be 50 meters apart. It may take only one reading, at say 40 meters away from the actual peak top. However, the second reading is taken for the tippy top of another peak. Note, in such a case the real height of the first peak is never noted. So it will not appear on the illustrations shown by world wind.
This is just an example of how a mountain peak is missed. Number of such things happen in this system of collecting elevation data because of which you may not get the expected or correct elevation imagery.
Besides, the problem discussed above for some areas which have very high relief it is not possible to obtain soundings. Therefore, SRTM data for such areas is not at all reliable. However, but since 2006, Both World Wind and Google Earth have installed new improvements in their systems for getting elevation data. Data from a number of other sources also has, been used for creating 3 dimensional views of mountains across the world. You can get accurate 3D views of most, important mountains like Matterhorn, Everest, etc.
Collecting elevation data for cities is even more difficult. Since the sounding is taken in the form of a grid and at some distance from each other, the elevation data varies greatly. This is because one sounding may hit a tall building and the second can hit a car, then the third may hit a 3-story building. All this, makes the elevation imagery for cities appear like a field containing randomly placed spikes.
Therefore NASA World Wind recommends that, while viewing a city turn of the elevation. This you can do pressing 0 key.
Also note that the different surfaces reflect the radar waves different. Therefore the readings obtained are different even if the two surfaces are at the same elevation. For example, the air plane runways appear bumpy due to this phenomenon.
Which is a better program NASA World Wind or Google Earth?
Both NASA World Wind as well as Google Earth are sophisticated programs. Both of them have amazing feature sets, and they also have features that the other will benefit from.
Even if they are similar programs, it is not fare to compare as both of them have different focuses, philosophies and development history. So both of them are used by people for the purposes which they want to accomplish.
Questions related other cache and data
Can adjust the amount of cache?
Yes it is certainly possible. For this you just need to press ALT+Q for brining up a dialog box, at the places where you want to change this setting.
Is it possible to copy and put my cache data on another computer?
Yes it is possible. You can get information about it at the World Wind central forum.
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