[Proj] cs2cs syntax help
peifer at gmx.eu
Thu Oct 24 01:52:29 EST 2013
On 2013-10-24 6:46, Szilard Albert wrote:
> The task is to convert UTM Zone 53 XY coordinates into Lat/Lon
> coordinates, keeping datum.
For this task, you don't really need cs2cs. proj -I or invproj can be
used. See below.
> I am using:
> *cs2cs -W2 +proj=utm +zone=53 +south +datum=WGS84 +to +proj=latlong
> 669734.6 7607027.2
> 136d38'24.07"E 21d37'54.60"S 0.000*
> getting a result that seems fine.
> However, the following issues arise:
> 1. My input data is on the GDA94 datum. When I try +datum=GDA94 (or
> GDA), I get
> projection initialization failure
> cause: unknown elliptical parameter name./
proj -ld (or cs2cs -ld) gives the list of known datums. GDA or GDA94 are
not mentioned there. However, you do not have to worry, as you anyway
want to keep the datum.
> Am I safe using WGS84, since the difference between these 2 datums is
> less than 1 m? (http://www.geoproject.com.au/gda.faq.html).
> 2. I have heaps of other parameters of my input data - as below - should
> any of these be incorporated in my command,
> or datum and zone are enough?
> Datum GDA94
> Spheroid GRS80
> Semi-major axis
> Projection UTM MGA Z 53
> Central meridian 135 E
> False E/N, Scale factor 0.9996 etc
I would simply use: invproj -W2 +proj=utm +zone=53 +south +ellps=GRS80
Other parameters like central meridian, scale factor, etc. do not need
to be specified explicitly. They are implied through +proj=utm and +zone=53.
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