North American Overlay Mapping


The 'TerraServer' interface provides a quick and easy way to access the huge collection of USGS satellite photos and topographical maps held at the Microsoft TerraServer website, one of the world's largest online databases.

With your Internet connection established in the usual way, click 'Tools' > 'Terraserver'. A new tool box will open with a line of colored spots, one for each Map-Pin currently selected.

These map pins act as the base location for a satellite photograph or topographical map; click on one, and a new browser will open with the requested image. You can specify the resolution (1-512 metres per pixel), the height and width of the photo (in pixels, where 1 pixel= 1/72 inch), whether grid-lines are added to the photo (useful for geo-referencing the view) and the type of view returned. This will usually be 'Aerial Photo', though if your position is over a major urban area, you may be able to choose the type 'Urban Areas' and get a high resolution color image that you can zoom down to a resolution of 0.25m !!

Note: there seems to be no guidelines as to which cities are presently covered by the color Urban Images, so choosing that view type is a matter of luck. If no image is available you will get a screen showing a uniform white textured surface, rather like the frosting on a Christmas cake.

Important: The TerraServer database only covers the United States of America.