On Saturday 17 March 2007 16:58, Doug McGarrett wrote: > On Saturday 17 March 2007 13:13, Roger Oberholtzer wrote: > > On Fri, 2007-03-16 at 19:15 -0400, Doug McGarrett wrote: > > > The GPS downloads the Zulu time with every transmission. > > > The only delay would be decoding the actual transmission. > > and it went on from there, in the list. I think a lot of us would > like to know, if it is within the clearances of your company, why you > are trying to pinpoint the location of a vehicle moving at 60 MPH or > so (100KPH) to within 1 meter. Such a vehicle would probably be > moving slower than the old German Buzz-bomb, but faster than a > taxicab, and who cares what the exact position of a cab is, so why > would you want to know to that accuracy?
Here's one example of why (taken from a project I did recently): You capture video out the sides of the vehicle and correlate each frame with the precise location. Then when someone wants to see what a particular location looks like (this was done primarily in business districts, but the problem doesn't change all that much when you slow to 40 or 50 kph), you geocode the address in question (often derived from a keyword search on a business directory) and display the location of the storefront. Another project, started at Stanford and then taken up by Google, uses laser scanners to build three-dimensional models of a city's buildings (at least those faces of the buildings that can be seen from publicly accessible streets and roads). GIS applications are manifold, and only just beginning to be developed. The ability to accurately and precisely locate a vehicle (or a person walking, for that matter) is often a key to capturing real-world information. Another example is capturing street maps. It's actually big business, and the firms that do this use vehicles very much like those described by Roger to capture current street networks. They simply (though in reality it's far from simple) drive the entire street and road network on an ongoing basis (things change rapidly, especially in urban areas) and build street maps from the sequences of captured (captured, augmented and corrected) GPS coordinates. > --dm Randall Schulz -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
