NASA World Wind FAQ
Are the real-time images available for world wind?
-The imagery should be compressed from gigabytes to several hundred megabytes if the sever has to send it to the users.
Even on compressing the images to several hundred megabytes a great amount of bandwidth will be required for the server. Even if this is achieved by some means, the high speed Internet connection of most of the users is not fast enough to update the data every hour.
However alternatively for Global Clouds, MODIS, and NRL Weather are so frequently updated that they can be called real-time images
What is the matter with colors for the new Landsat. Why is my area not covered for it?
The NLT Landsat was developed with the aim of providing more colors to the images. However the quality of NLT dataset is not as high as original Landsat data sets like “OnEarth” or “Geocover”. Nevertheless most of the articles are covered at a 30 meter resolution.
How to load the 0.25 meter resolution in the same way in which the screenshot of DC is shown as a sample?
For doing so you can select Layer Manager ->Images->USGS Urban Area Ortho. Alternatively you can also do this by clicking USGS urban button.
Why only white tiles are appearing while trying to view USGS Urban data!
The urban data is not available for all categories. Therefore it may be possible that these images are not available for your town. Therefore check whether the town you are viewing is listed in the Terraserver website or the Urban Area list. If it is not, you should see only whitish green patch on the screen and nothing else. You can take the help of Urban layer Highlighter to locate areas.
How are the USGS layers used?
USGS data set is the US Geological Survey. Therefore you can get these images only for the United States. However or some other regions also such data is available in most of the cases it is not free. So NASA does not incorporate them in World Wind. The procedure for using it is briefly described at NASA World Winds support section.
Issues with SRTM: the does not work as expected?
This can happen due to several factors. If the area is completely flat, you must be looking at an area which is above or below 60 degree latitude. For these areas elevation data is not available because the satellite took images only for the regions around equator. Or the latitudes above 60 degrees the measurements taken are too extreme and therefore recent data is not available for them.
However if this is not the case and you are looking inside 60 degrees it is likely that the data for this region may have been taken through sonar measurements or bats echolocation. In such cases the elevation is sounded from a satellite.
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