[Proj] State Plane Coordinate Zone 6 Conversion Help

[Ed McNierney]

Matt -

The epsg definitions are not "zones", but sets of initialization
parameters, so the syntax in your first example should be

echo "6293409 1793361" | proj -I -f %.4f +init=epsg:26946

which will give you the same results as your second example.  So I'm
going to guess that you have input data in California NAD83 State Plane
Zone 6 FEET, not meters (it is very helpful of we Americans to provide
so many choices to field of geodesy).  That would be EPSG code 2230, and
if you try this:

echo "6293409 1793361" | proj -I -f %.4f +init=epsg:2230 

I expect you'll get reasonable results.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: +1 (978) 251-4242
Fax: +1 (978) 251-1396
ed at topozone.com
-----Original Message-----
From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Matt Bartolome
Sent: Friday, February 23, 2007 4:55 PM
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] State Plane Coordinate Zone 6 Conversion Help

Thanks Ed,
Ok. Specifying the wrong method was my first mistake. Now I've got:

$ echo "6293409 1793361" | proj -I -f %.4f +proj=lcc +zone=26946
48.4666 0.5464

Spelling it out:
$ echo "6262009 1854017" | proj -I -f %.4f +proj=lcc
+lat_1=33.88333333333333 +lat_2=32.78333333333333
+lat_0=32.16666666666666 +lon_0=-116.25 +x_0=2000000 +y_0=500000 
+ellps=GRS80 +datum=NAD83
-67.7015        35.2628

So something is still very wrong with what I'm doing. The agency I got
the data from confirmed it is the Lambert Method, GRS80 Spheroid,
NAD83 so I'm not sure what else to do.

-Matt


On 2/23/07, Ed McNierney <ed at topozone.com> wrote:
> Matt -
>
> You say you have "State Plane Zone 6" coordinates, but you're telling 
> PROJ that they're UTM Zone 6 coordinates, and that's not at all the
same thing.
> The California State Plane NAD83 projections are Lambert Conformal 
> Conic projections, not UTM.
>
> I expect in your second example the lat_0 and lon_0 parameters are 
> being ignored, since the UTM projection does not use those parameters.
>
> The EPSG code for NAD83 California Zone 6 is 26946, so you may want to

> just specify that as your input projection defintion, or spell it out:
>
> +proj=lcc +lat_1=33.88333333333333 +lat_2=32.78333333333333
> +lat_0=32.16666666666666 +lon_0=-116.25 +x_0=2000000 +y_0=500000 
> +ellps=GRS80 +datum=NAD83
>
>      - Ed
>
> --
> Ed McNierney
> President and Chief Mapmaker
> Maps a la carte, Inc. / TopoZone.com
> 73 Princeton Street, Suite 305
> North Chelmsford, MA  01863
> Phone: (978) 251-4242
> Fax: (978) 251-1396
> ed at topozone.com
>
> > From: Matt Bartolome <mattxbart at gmail.com>
> > Reply-To: "PROJ.4 and general Projections Discussions"
> > <proj at lists.maptools.org>
> > Date: Fri, 23 Feb 2007 11:33:51 -0800
> > To: <proj at lists.maptools.org>
> > Subject: [Proj] State Plane Coordinate Zone 6 Conversion Help
> >
> > Hello list,
> >
> > I'm trying to convert state plane coordinates from zone 6 (san diego

> > county, california)  to latitude longitude and I'm having trouble.
> >
> > $ echo "6262009 1854017" | proj -I -f %.4f +proj=utm +zone=6
> > +ellps=GRS80 +datum=NAD83 +units=m
> >
> > -100.1078       11.6424
> >
> > I've also tried plugging in some computed constants I found but I'm 
> > not sure if they are accurate.
> >
> > $ echo "6262009 1854017" | proj -I -f %.4f +proj=utm +ellps=GRS80
> > +zone=6 +lat_0=32.166667 +lon_0=-116.25 +datum=NAD83 
> > ++k=0.999954142490
> >
> > -100.1078       11.6424
> >
> > I'm pretty sure the datum NAD83 is correct, as well as the GRS80 
> > ellipsoid. The values should be close to -116, 32.
> >
> > Thank you,
> > Matt
> > _______________________________________________
> > Proj mailing list
> > Proj at lists.maptools.org
> > http://lists.maptools.org/mailman/listinfo/proj
>
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