NASA World Wind FAQ
Are high resolution images available for regions outside United States?
The USGS data is available only for the United States. However, high resolution imagery may be available for some other regions also. However, most of them are licensed and therefore they are not free. So NASA World Wind does not provide imagery from such sources. Nevertheless some non restricted data sets may be available for some regions. NASA World Wind is searching for such data sets and therefore if you know one, you can tell NASA World Wind.
The add-on like OneEarth is an attempt for making use of public WMS servers to provide high resolution imagery. Such imagery is available for some countries.
By making use of Virtual Earth plugin you will be able to view high resolution data for countries like UK, Italy, Australia, Japan.
NASA World Wind would be able to provide you high resolution data only if the government of your country has released GIS data. So you can request it for this data.
Crazy circles are appearing on the screen?
The crazy circles are crop fields which are watered by central pivot irrigation method.
When was the imagery photographed?
The imagery for different layers was photographed at different times. The NLT Landsat, Geocover, and OnEarth Landsat were photographed between The years 1999 to 2003. However the most active year among these was the year 2000. the Geocover 1990 was photographed between the years 1987 and 1993.
The USGS 1M Digital Ortho layer has a greater range which is from the year 1990 to 2000. you can search for a location in the United States with the help of TerraServer and then look for the USGS entry. The USGS Topo maps vary even more. They can be one or two years back, or they can be from several decades back. Note especially the building locations and streets can be some decades back. The USGS Urban Area Ortho data has be taken between the years 2001 to 2004. Note these images are still being photographed. You can know about the age of a dataset at the USGS site.
Are real-time images available for the world?
This has not yet been possible and further note that this wont be possible in the near future as well. For doing so there need to be a network of satellites especially for this purpose. Moreover if such network of satellites is available, to get the resolution which you currently get from NASA World Winds first load, each of the cameras should in total be 100 mega pixels. Military is believed to have such a network. However its cost is so high that it cannot be used for a service like NASA World Wind.
The cost increases still further because the images need to be received on the ground and then they are to be processed. Then it is important to combine them at the points where they overlap each other and the distortion caused by earths curvature needs to be corrected.
Technorati Tags: NASA World Wind, FAQ
Tags: NASA World Wind
