[Proj] State Plane Coordinate Zone 6 Conversion Help

[Ed McNierney]

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
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