WGS84 to metres conversion (very accurate)

Discussion in 'General GPS Discussion' started by Jornt v.d. Wiel, Jul 13, 2005.

  1. Hello,

    I was wondering if anyone has a very accurate formula to calculate
    meters to lat/lon (wgs84) and visa versa. The accuration has to be
    around centimeters. The formulas I found on the web did not have
    that amount of accuration.
    I am very aware of the fact that GPS which gives the coordinates has a
    deviation of 1-2 meters, but that isn't of any problem for my specific

    Jornt v.d. Wiel, Jul 13, 2005
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  2. Jornt v.d. Wiel

    Sam Wormley Guest

    See the coordinate transfer soltware and online links i the
    box near the top of

    such as NGS Geodetic Tool Kit
    Sam Wormley, Jul 13, 2005
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  3. Jornt v.d. Wiel, Jul 13, 2005
  4. Jornt v.d. Wiel

    Chuck Taylor Guest

    For UTM, NGA TM 8358.2, from
    has formulas that give centimeter accuracy.

    For UTM and other projections,
    Snyder, John P. _Map Projections--A Working Manual_.
    U. S. Geological Survey Professional Paper 1395.
    (available in hardcopy only)

    Or do you mean an Earth-centered Cartesian coordinate frame with
    coordinates in meters?
    Chuck Taylor, Jul 13, 2005
  5. The idea is that i have the WGS84 coordinates of some Access Point
    (WiFi). Now I need the coordinates for when I am say 3 meters to
    the left. My specific task is to determine that position as precise
    as possible.
    Jornt v.d. Wiel, Jul 13, 2005
  6. Jornt v.d. Wiel

    Sam Wormley Guest

    Aviation [Navigation] Formulary V1.37 by Ed Williams
    Sam Wormley, Jul 13, 2005
  7. Jornt v.d. Wiel

    Chuck Taylor Guest

    The formula described here might do the job:


    It's a great-circle approximation, but for distances on the order of 3
    meters, the error should easily be within your centimeter threshold.
    The advantage is that the formula is much simpler than the UTM

    Note that
    (1) d in the formula is an angle, not a linear distance; read
    the introduction section at
    (2) that document uses the convention that west longitudes
    are positive. If you find other formulas in that document
    useful, you may need to take that convention into account.

    If you don't think either that solution or one using a projection like
    UTM will be adequate, you might also be interested in the coordinate
    transformations described here (geodetic to EFG to a local NED/ENU and

    <URL:http://www.eiserloh.org/~peter/doc/tspidoc/html/main.html> or
    Chuck Taylor, Jul 13, 2005
  8. Jornt v.d. Wiel

    jimirwin Guest

    You don't need fancy algorithms to obtain millimeter or better accuracy at
    distances of a few km or less. See http://groups-
    jimirwin, Jul 13, 2005
  9. Jornt v.d. Wiel

    ed_w Guest


    will be good to about 1 part in 10^12 at three meters.

    ed_w, Jul 14, 2005
  10. Mathematicians should not use GPS. They should leave it to walkers,
    mountaineers, drivers and sailors.
    Dennis Pogson, Jul 14, 2005
  11. I was wondering if anyone has a very accurate formula to calculateI must admit that I have my doubts about any real application requiring
    centimeter accuracy. Such accuracy can only ever be theoretical and of
    little practical use. Unfortunately (?) we do not live on a perfect shiny
    sphere (or even spheroid). Our planet is covered in lumps and bumps and
    dips etc. etc. WGS84, like all datums is just an approximation which works
    well in some places, not so well in others. I fear that centimeter accuracy
    in real-world surface distance measurement may be asking too much of it -
    but maybe that's not your intention.

    Perhaps a related question should be centimeter accuracy in what distance?
    If you want distances of the order of thousands of kilometers to the nearest
    centimeter then surely that is expecting too much. I have a suspicion that
    even centimeter accuracy in distance of the order of a few meters might be
    expecting too much but I will defer that to those with better technical
    knowledge of the issues.

    Keith Sheppard, Jul 18, 2005
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