Hi Louis, Pat, Didn't see your (XYZ) question answered yet, so...
The coordinates cited below are almost certainly ECEF or "Earth Centered, Earth Fixed", as described by Peter H. Dana (which is about all I know about this :)... [begin quote] * Earth centered, earth-fixed, X, Y, and Z, Cartesian coordinates (XYZ) define three dimensional positions with respect to the center of mass of the reference ellipsoid. * The Z-axis points toward the North Pole. * The X-axis is defined by the intersection of the plane defined by the prime meridian and the equatorial plane. * The Y-axis completes a right handed orthogonal system by a plane 90 degrees east of the X-axis and its intersection with the equator. [end quote; from... http://www.colorado.edu/geography/gcraft/notes/coordsys/coordsys_f.html <Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder> see Coordinate Systems / Global Systems / ECEF X, Y, Z for links to a couple of handy diagrams] The US National Geodetic Survey has a little interactive converter at http://www.ngs.noaa.gov/TOOLS/XYZ/xyz.html; plugging in the XYZ values you gave (in *meters*, he said, desperately trying to keep this on topic :-), it spits out... ================================================================= X (Meters) Y (Meters) Z (Meters) ELLIPSOID INPUT = +4203644.0 +162934.0 +4778193.0 GRS80 ================================================================= LATITUDE LONGITUDE ELLIP_HT ELLIPSOID HDDMMSS.sssss HDDDMMSS.sssss (Meters) ------------- -------------- ---------- --------- N484946.42106 E0021310.86102 120.2941 GRS80 ...which is indeed somewhere in the vicinity of Paris. :) Cheers, Bruce H. On Wed, 4 Dec 2002, Louis JOURDAN wrote: > At 10:51 +1100 02/12/4, Pat Naughtin wrote: > >Dear Louis, > > > >Thanks very much for this information. > > > >You remind me of a story I heard of a poet (name forgotten) who found > >himself in a Master of Business Administration program at Harvard. He said > >the experience was like wanting a sip of water to moisten his throat and > >they supplied him with a high-pressure fire hose (of information). > > > >However, that said, I enjoyed reading the web page you supplied - it was > >fascinating but I couldn't figure out this reference: > > > > X coordinate (m) : +4203644 (m) > > Y coordinate (m) : +162934 (m) > > Z coordinate (m) : +4778193 (m) > > > >In particular, where is the datum for these numbers? > > > >Do you know what these numbers mean? > > Not really. I found the referred web site simply by typing on a > Google search page "S�vres longitude". From the context of the page, > I understand that the coordinates given are those of a GPS station > (beacon ?) installed in 1998 in the BIPM premises at S�vres. > > Anyway, it was intellectually refreshing. > > Louis
