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Thread: How to convert IGN X,Y,Z coords to GPS

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    still learning... gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan is a glorious beacon of light gallathan's Avatar
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    How to convert IGN X,Y,Z coords to GPS

    OK having a brain fart ;-( Lots of the Series Blue Mpas have coords for cave sites, but they're not GPS coords. Ideally I'd like to find a formula for doing the conversions - I'm a java programmer so would like to knock up a spreadsheet / java program to do the conversions, but don't really understand the lingo / issues involved. Anyone know how to do the conversions/ is there some site that explains it in plain english???
    Thanks in anticipation

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    RBW Member SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK's Avatar
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    Re: How to convert IGN X,Y,Z coords to GPS

    Quote Originally Posted by gallathan  View Original Post
    OK having a brain fart ;-( Lots of the Series Blue Mpas have coords for cave sites, but they're not GPS coords. Ideally I'd like to find a formula for doing the conversions - I'm a java programmer so would like to knock up a spreadsheet / java program to do the conversions, but don't really understand the lingo / issues involved. Anyone know how to do the conversions/ is there some site that explains it in plain english???
    Thanks in anticipation

    I assume you are talking about French maps? There is a lot of good stuff about coordinate systems here: IGN - Coordinates and measurement of the earth -

    the .pdf download on coordinate systems ends with a simple NTF to GPS conversion. The difference appears to be a couple of hundred meters.

    unfortunately geodetics and plain English seem to be mutually exclusive.

    Once you have read and understood that lot :p you can download this NGA: (U) GEOTRANS 2.4.1 Geographic Translator (UNCLASSIFIED) and do precision conversions. Be warned you will be trying to put French data into American military software, its not straight forward.


    Simon
    Last edited by SimonK; 10th July 2007 at 20:31.

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    Re: How to convert IGN X,Y,Z coords to GPS

    yes, i am talking about french maps 1:25000 IGN or Series bleue. Thanks for info, nice one.Want to convert x,z,y coords on map to GPS coordssuiable for a Garmin Nuvi 360 GPS

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    RBW Member SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK is a glorious beacon of light SimonK's Avatar
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    Re: How to convert IGN X,Y,Z coords to GPS

    First a health warning: I have never had to deal with French maps so I might be missing something but the following should work.

    The setup menu in a GPS usually gives you the option to change the grid system it operates in - Lat/Long, British National Grid, UTM etc. If yours has the option to use NTF (New Transform France) then that's all you need to do. Otherwise set it WGS84 and UTM and then use the simple conversion in the coordinates .pdf to correct the position the GPS gives you.
    Or you could wait until IGN issues the map with a UTM grid but that might take a while.

    Simon

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    Re: How to convert IGN X,Y,Z coords to GPS

    There is a piece of software on the IGN website which will do the translation. The minor problem is that you have to know which regional version of the co-ord system your location is in or if it is using the generic system...

    The simplest thing, find the cave with a map (and compass if necessary) on foot, stand by the entrance, press the waypoint button on your GPS. It saves the permanent loss of higher brain function and thoughts of suicide which trying to figure out the Lambert sysem causes :D

    Cheers,

    Stuart

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    Re: How to convert IGN X,Y,Z coords to GPS

    Found it, it's called Circé:

    IGN - Outils -

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    RBW Member Tautaz is an unknown quantity at this point Tautaz's Avatar
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    Re: How to convert IGN X,Y,Z coords to GPS

    Just to help,

    on IGN maps you've got all around the draw map a blue line, it's the UTM to GPS transfert system, you need to make the squares X,Y and you got the point to enter in your GPS or vice versa.

    There is too a software "carto explorer" very helpful to convert your geodesic datas on your maps.


    try this out too there is plenty of conversion charts lambert to geo for exemple.

    http://www.ign.fr/telechargement/MPr...CE/transfo.pdf

    Cheers.


    David

    I use IGN maps at my job
    Last edited by Tautaz; 11th July 2007 at 12:37. Reason: adding the ign link

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