Some important basic of NASA World Wind
The OneEarth add-on is an attempt for making use of public WMS servers to provide high-resolution imagery. There are many countries for which data is available.
You can also use the Virtual Earth plug as it has high resolution data for countries like United Kingdom, Australia, Italy, Japan, etc.
If high resolution imagery is not available for your country, you demand for releasing such data to politicians of your country.
Why are these crazy circles appearing on the maps?
The crazy circles are crop watered fields. For watering these fields, a technique called central pivot irrigation is used. Because fields start appearing like circles when looked from the sky.
What is the age imagery which NASA World Wind provides?
This will depend on the layer. The NLT LandSat, Geocover and OnEarth Landsat are taken between the years 1999 to 2003. Among this period, the year 2000 was the most active one. The Goecover 1987 has been taken between the years 1987 to 1993. The period of USGS 1 meter Digital Ortho varies even more. It was taken between the years 1990 to 2000. You can find out the time of these images by searching for a particular place through TerraServer and then looking for the USGS entry.
The USGS Topo maps can be from the last few years to several decades back. Particularly, the views for buildings, streets, etc are quite out of date. The USGS Urban Area Ortho is taken between the years 2001 to 2004. These images are still being photographed for some areas and therefore they are much up to date. You can view the ages of these images at the USGS site.
Is it possible to get real time images of the world?
This is neither possible this moment neither is there any hope in the near future. The resources required for doing this are enormous. Moreover, there is a technological limitation as well. The problems in doing so are given given.
The first requirement is that of a network of satellites, that is completely dedicated to take images for earth. Moreover, for providing the resolution of the base layers of NASA World Wind, which appear at the time of loading, the satellites need to have cameras of about 100-mega pixel resolution. The military may have such a network, however it is not possible for anyone else.
Then the second requirement is that of system capable of receiving such data on the ground and processing it. After processing this data, it has to be combined for the regions for which it overlaps and corrected for the distortion. Distortion is caused due to curved shape of earth. During this the size of this imagery is compressed from several 100 megabytes to a server that has to send it out to everybody. This will require an enormous amount of bandwidth for the server. Note that such a bandwidth is not practically possible at this moment.
Even if this is managed somehow, the internet connection of most users, currently is too slow, for having even 1 update per hours.
However, the images climatic conditions are near real-time. Therefore the NRL weather, Global Clouds, MODIS etc are all updated every 3 to a maximum of 24 hours.[tags] NASA, NASA World Wind, [tags]
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