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i don know if this is the right place to publish this. i am working with business object tool traying to make a kml file to be imported on google maps. I dont know much about geographic systems, but i begin to understand some basic thinks, well, i have a database which give me a local coordinates i know that becouse the gps has an appfile which has a grid configured and the database says me that units are meters.

The app file shows this information

Site Point Pairs:
Number Of Points: None

Ellipsoid:
Name: (WGS 84) Semi Major Axis: 6,378,137.000 Semi Minor Axis: 6,356,752.314 Flattening: 1/298.2572215381 Eccentricity:
First: 0.0818191911 Second: 0.0820944382

Datum Transformation:
Name: (WGS 84) Method: Molodensky Parameters: Direction: WGS84 to Local Translation X: 0.000 Translation Y: 0.000 Translation Z: 0.000

Geoid Model:
Name: Subgrid of MEXICO97 (Mexico)
Method: Grid Geoid Grid File Name:

Coordinate System:
Name: 12 North Group: UTM

Projection: Type: Mercator Transversa Parameters: Latitud central: 0°00'00.00000"North Longitud central: 111°00'00.00000"West Falso norte: 0.000 Falso este: 500,000.000 Factor de escala: 0.9996 AZI Parameters: Azimuth Direction: North Azimuth Positive Coordinate Direction: NorthEast Embedded Data: True Embedded Geoid Grid Extents Minimum Latitude: 30°53'60.0000"North Maximum Latitude: 31°18'0.0000"North Minimum Longitude: 247°03'60.0000"East Maximum Longitude: 247°33'60.0000"East

CSIB Version: 10.50 CSIB Format: Big Endian


the database shows me this kind of values

vehicle x y z

VE-28 328279 3457947 -48
VE-28 328295 3459609 192
VE-28 328288 3459617 193
VE-28 328304 3459622 192
VE-28 328220 3457362 -112

i would like to conver this unit into gps information throught some formula. or get the gps give the gps coordinate to the database instead of the local coordinate. if something is confusing please ask me for more information.

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1  
Its called coordinate transformation or projection. gdal.org/gdaltransform.html is one tool. spatialreference.org/ref/epsg/26912 is UTM12. 4326 is WGS84 (standard GPS output). –  BradHards Jul 14 '13 at 8:03
    
Check your database, if your database is spatially enabled there's a good change that already provides a build-in function for transforming coordinated from one system to another. –  nickves Jul 14 '13 at 9:45

2 Answers 2

up vote 3 down vote accepted

Best method to visualize your data is the free software Quantum GIS. You can add your data with Layer -> Add delimited text. Select space as delimiter; x and y will be automatically selected.

From the information you gave, the projection is WGS84 UTM 12N, EPSG:32612.

You can add Google satellite background with the openlayers plugin, and your points will look like this:

Picture removed

If the points are in the right place, you can rightclick on the point layer -> Save as, select keyhole markup language (KML) as format, select a new filename, and EPSG:4326 as CRS for the kml. You can check to add the kml to the canvas, and the new points should fall on the same place as the first ones.

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Thanks Andre, sorry for being late, I have a list with local coordinates in meter, if posible with this software to plot this local coordinates? how can i start i just downloaded this tool. Thanks in advanced –  Miguel Jul 24 '13 at 22:45
    
Andre, i have a list of local coordinates based in a base station, where do i put the information of coordinates of the base station, the local coordinates that i have are relatives to that base station, does this work for me even with this condition? –  Miguel Jul 25 '13 at 0:03
    
If you have the coordinates of the base station, use an excel sheet to calculate the sum of coo1(base) + coo2(relative to base). Then export as delimited text and add it as a new layer. –  AndreJ Jul 25 '13 at 5:16
    
Thanks Andre, i got wrong the idea about coordinates are relatives to base station, it is only used for enhance the accuracy, the coordinates the database gives me are about the grid, thanks for your time your solution, software you suggested worked for me, thanks again. See you Andre, this site really rocks becouse of people like you. –  Miguel Jul 26 '13 at 17:50

It seems that you want to have longitude and latitude (i.e. WGS84 coordinate system) instead of the projection used in your system. The key is to identify your source SRID (http://en.wikipedia.org/wiki/SRID) and your target SRID (i.e. 4326). If your database is postgis, check the ST_Transform(geometry,SRID) function.

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Thanks Fabrice Marchal the database is oracle but i am not allowed to manipulate it, i have to do something out of it. I am goint to ask. –  Miguel Jul 24 '13 at 17:56

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