[Proj] lat/long to northing/easting and back again

[Roger Oberholtzer]

On Mon, 2009-03-16 at 13:38 +0200, support.mn at elisanet.fi wrote:
> Hello,
> 
> how about using pj_inv() in the proj.4 library?

OK. But does that do an inverse of all projections? I seem to recall a
discussion a few months ago about this. IIRC, not all inverse
calculations has the same accuracy. In fact, I have some flexibility in
which forward calculation is done: it will only be used internally.
Externally, all will be WGS84 lat/longs. 

> 
> regards: Janne.
> 
> -------------------------------------------------
> 
> Roger Oberholtzer [roger at opq.se] kirjoitti: 
> > Gee, no opinions/suggestions? Especially on the best way to convert
> > northings/eastings back into wgs84?
> > 
> > On Tue, 2009-03-03 at 07:56 +0100, Roger Oberholtzer wrote:
> > > I have always used proj to convert WGS84 lat/long values to
> > > northing/easting values in various parts of the world. In doing so, I
> > > usually need to interpolate between points to find specific locations.
> > > These interpolated locations have always been reported as
> > > northing/easting values in meters. Job finished.
> > > 
> > > I now have a use where, after determining the interpolated
> > > northing/easting, I need to convert the location back into lat/long in
> > > degrees. This I have never done with proj.
> > > 
> > > My question is, if you had to locate a position between two lat/long
> > > values, how would you best do this with proj? The source data in my case
> > > is WGS84 values from a Trimble GPS. The 'interpolated' lat/longs should
> > > also be reported in WGS84. In reality, the values will be collected
> > > throughout Germany. But everything is requested to be provided in WGS84.
> > > 
> > > I use the C API for this. But any pointers are welcome. If I have left
> > > out any important detail, just ask.
> > > 
> > > 
> > > -- 
> > > Roger Oberholtzer
> > > 
> > > OPQ Systems / Ramböll RST
> > > 
> > > Ramböll Sverige AB
> > > Krukmakargatan 21
> > > P.O. Box 17009
> > > SE-104 62 Stockholm, Sweden
> > > 
> > > Office: Int +46 8-615 60 20
> > > Mobile: Int +46 70-815 1696
> > > 
> > > _______________________________________________
> > > Proj mailing list
> > > Proj at lists.maptools.org
> > > http://lists.maptools.org/mailman/listinfo/proj
> > -- 
> > Roger Oberholtzer
> > 
> > OPQ Systems / Ramböll RST
> > 
> > Ramböll Sverige AB
> > Krukmakargatan 21
> > P.O. Box 17009
> > SE-104 62 Stockholm, Sweden
> > 
> > Office: Int +46 8-615 60 20
> > Mobile: Int +46 70-815 1696
> > 
> > _______________________________________________
> > Proj mailing list
> > Proj at lists.maptools.org
> > http://lists.maptools.org/mailman/listinfo/proj
> 
> _______________________________________________
> Proj mailing list
> Proj at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/proj
-- 
Roger Oberholtzer

OPQ Systems / Ramböll RST

Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden

Office: Int +46 8-615 60 20
Mobile: Int +46 70-815 1696