[Gdal-dev] definition in the EPSG file

[Zhonghai Wang]

Hi Frank,

the epsg definition is totally correct, sorry for a question like this. I've
read some references, and if we said UTM ZONE 32N with the GRS80 ellipsoid,
all the other parameter will set default.

thanks frank.

zhonghai


On 7/12/06, Frank Warmerdam <warmerdam at pobox.com> wrote:
>
> Zhonghai Wang wrote:
> > Hi guys,
> >
> > I noticed that some definitions for the EPSG codes in the epsg file is
> > not so clear, which means there are no parameters for the epsg codes,
> > for example:
> >
> > # ETRS89 / UTM zone 32N
> > <25832> +proj=utm +zone=32 +ellps=GRS80 +units=m +no_defs  <>
> >
> > the EPSG code for this one is 25832, but there are no other parameters
> > any more, such as longitude, latitude, central meridian, false northing,
> > false easting.....
>
> Zhonghai,
>
> I'm not sure what is wrong with the above definition.  It is the preferred
> way of expressing UTM coordinate systems in PROJ.4, and is generally more
> readable than the full "transverse mercator with parameters" definition
> we see in WKT.
>
> > and also this one:
> >
> > # NAD83(HARN)
> > <4152> +proj=longlat +ellps=GRS80 +no_defs  <>
> >
> > if the epsg code is defined like this, does it mean that the the EPSG
> > code is not valid for use or is not defined?
>
> In this case we don't really understand what to do about the HARN datum
> so we fallback to expressing things in terms of the underlying ellipsoid.
>
> It can be used, but it won't do HARN specific datum corrections for you.
>
> Best regards,
> --
>
> ---------------------------------------+--------------------------------------
> 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    | President OSGF, http://osgeo.org
>
>
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