[Shapelib] Coordinate System?

[sagent100]

Frank,
thank you very much.
the only doubt i have right now so is when we create an object with shaplib,
the coordinate points of the object, in which system must be ?

thank you!



Frank Warmerdam-2 wrote:
> 
> On Tue, Sep 30, 2008 at 12:09 AM, sagent100 <sagent100 at yahoo.com.ar>
> wrote:
>>
>> Hi,
>>
>> When I create a .shp file using shapelib, where we can indicate the
>> coordinate system ?
>> I want to create a file with lat/long wgs84 or UTM Zone 1 NAD 83  for
>> example.
>>
>> Another question:
>> When I open a .shp file using shapelib, how can I know the coordinate
>> system
>> the file has ?
> 
> sagen100,
> 
> The coordinate system will sometimes be found in an
> associated .prj file (same base name as the .shp, .shx and .dbf).
> If found it will be in ArcGIS "Projection Engine" format which is
> similar to OGC Well Known Text for coordinate systems.
> 
> Shapelib does not have any code to manipulate the .prj files.
> 
> If you want to assign a particular coordinate system, it is best
> for you to programmatically or manually create the .prj file
> yourself.  Major ESRI products are shipped with a collection
> of .prj files in the software distribution that you could use.  Or
> you can create an ESRI compatible .prj file with OGR or
> http://spatialreference.org.  For example:
> 
> http://spatialreference.org/ref/epsg/32737/esriwkt/
> 
> Much like styling, coordinate systems is considered
> to be outside the scope of shapelib, though it is addressed
> in the shapelib based OGR data access library.
> 
>   http://www.gdal.org/ogr
> 
> Good luck,
> 
> -- 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
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> 

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