I recommend the TerraServer white paper as a good read on the thinking
and technology behind one of the most compelling Internet applications
of recent years <http://terraserver.microsoft.com/library/wp.exe>. An
excerpt:
Satellite Images of the Urban World: Pictures have a universal appeal,
so it was natural to pick a graphical application. Aerial images of the
urban world seemed to be a good application. The earth's surface is
about 500 square tera-meters. 75% is water, 20% of the rest is above 70*
latitude. This leaves about 100 square tera-meters. Most of that is
desert, mountains, or farmland. Less than 4% of the land is urban. The
TerraServer primarily stores images of urban areas. Right now, it has
nearly five square tera-meters-and it grows as more data becomes
available.
Encarta, USGS, and SPIN-2 Themes: Terra Server has several different
views of the earth: the coverage map view, the Encarta World Atlas view,
the USGS image view, and the Sovinformsputnik-SPIN-2 view. We call each
of these a theme. The user may switch from one theme to another: perhaps
starting with the Encarta theme, then the SPIN-2 theme, and then the
USGS theme of the same spot. With time, we expect to have multiple
images of the same spot. Then the user will be able to see each image in
turn. Your grandchildren will be able to see how your neighborhood
evolved since 1990.
- dan