mapbuilder-proj

[Mapbuilder-proj] Bug or user error with lcc?

[David Z. <dz...@av...>]

Hello,

I am using proj4js, and I am having difficulty getting good projection with
a new projection definition.  It is entirely possible that I don't have the
correct syntax for the definition file (or that I am totally missing
something required), but it's giving results that are off by a factor of 3
in 1 dimension (either X or Y, but not both).

I am creating a definition for Pennsylvania State Plane, and this is the
file EPSG2272.js:

Proj4js.defs["EPSG:2272"] = "+proj=lcc \
+lon_0=-77.75 \
+lat_0=39.33333333333334 \
+lat_1=39.9333333333333 \
+lat_2=40.96666666666667 \
+y_0=0.0 \
+x_0=1968500.00 \
+ellps=GRS80 \
+datum=NAD83 \
+nadgrids=@null +no_defs";

I searched in http://www.epsg-registry.org/, and those are correct decimal
degrees values.  I try to transform the location of Philadelphia, PA (
-75.163808,39.951639 ), and I always get x:2189468, y:71889.  I am expecting
something like x:2694800,y:236500.

At first, I thought it was a ft/meter conversion, but when I add
"+to_meter=0.3048006096012192" to the definition, the projected Y coordinate
looks good, but the X coordinate is way off.

Any help would be greatly appreciated,
Thanks,
David

Re: [Mapbuilder-proj] Bug or user error with lcc?

[Richard G. <ric...@gm...>]

The false easting (x_0) must always be in meters, even for coordinate
systems that are in feet.


On Tue, Jul 1, 2008 at 3:03 PM, David Zwarg <dz...@av...> wrote:
> Hello,
>
> I am using proj4js, and I am having difficulty getting good projection with
> a new projection definition.  It is entirely possible that I don't have the
> correct syntax for the definition file (or that I am totally missing
> something required), but it's giving results that are off by a factor of 3
> in 1 dimension (either X or Y, but not both).
>
> I am creating a definition for Pennsylvania State Plane, and this is the
> file EPSG2272.js:
>
> Proj4js.defs["EPSG:2272"] = "+proj=lcc \
> +lon_0=-77.75 \
> +lat_0=39.33333333333334 \
> +lat_1=39.9333333333333 \
> +lat_2=40.96666666666667 \
> +y_0=0.0 \
> +x_0=1968500.00 \
> +ellps=GRS80 \
> +datum=NAD83 \
> +nadgrids=@null +no_defs";
>
> I searched in http://www.epsg-registry.org/, and those are correct decimal
> degrees values.  I try to transform the location of Philadelphia, PA (
> -75.163808,39.951639 ), and I always get x:2189468, y:71889.  I am expecting
> something like x:2694800,y:236500.
>
> At first, I thought it was a ft/meter conversion, but when I add
> "+to_meter=0.3048006096012192" to the definition, the projected Y coordinate
> looks good, but the X coordinate is way off.
>
> Any help would be greatly appreciated,
> Thanks,
> David
>
> -------------------------------------------------------------------------
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> _______________________________________________
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>
>



-- 
Richard Greenwood
ric...@gm...
www.greenwoodmap.com

Re: [Mapbuilder-proj] Bug or user error with lcc?

[David Z. <dz...@av...>]

Yes!  A false easting of 600000 ( "+x_0=60000" ) works like a charm --
thanks for the tip.

David

On Tue, Jul 1, 2008 at 10:04 PM, Richard Greenwood <
ric...@gm...> wrote:

> The false easting (x_0) must always be in meters, even for coordinate
> systems that are in feet.
>
>
> On Tue, Jul 1, 2008 at 3:03 PM, David Zwarg <dz...@av...> wrote:
> > Hello,
> >
> > I am using proj4js, and I am having difficulty getting good projection
> with
> > a new projection definition.  It is entirely possible that I don't have
> the
> > correct syntax for the definition file (or that I am totally missing
> > something required), but it's giving results that are off by a factor of
> 3
> > in 1 dimension (either X or Y, but not both).
> >
> > I am creating a definition for Pennsylvania State Plane, and this is the
> > file EPSG2272.js:
> >
> > Proj4js.defs["EPSG:2272"] = "+proj=lcc \
> > +lon_0=-77.75 \
> > +lat_0=39.33333333333334 \
> > +lat_1=39.9333333333333 \
> > +lat_2=40.96666666666667 \
> > +y_0=0.0 \
> > +x_0=1968500.00 \
> > +ellps=GRS80 \
> > +datum=NAD83 \
> > +nadgrids=@null +no_defs";
> >
> > I searched in http://www.epsg-registry.org/, and those are correct
> decimal
> > degrees values.  I try to transform the location of Philadelphia, PA (
> > -75.163808,39.951639 ), and I always get x:2189468, y:71889.  I am
> expecting
> > something like x:2694800,y:236500.
> >
> > At first, I thought it was a ft/meter conversion, but when I add
> > "+to_meter=0.3048006096012192" to the definition, the projected Y
> coordinate
> > looks good, but the X coordinate is way off.
> >
> > Any help would be greatly appreciated,
> > Thanks,
> > David
> >
> > -------------------------------------------------------------------------
> > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW!
> > Studies have shown that voting for your favorite open source project,
> > along with a healthy diet, reduces your potential for chronic lameness
> > and boredom. Vote Now at http://www.sourceforge.net/community/cca08
> > _______________________________________________
> > Mapbuilder-proj mailing list
> > Map...@li...
> > https://lists.sourceforge.net/lists/listinfo/mapbuilder-proj
> >
> >
>
>
>
> --
> Richard Greenwood
> ric...@gm...
> www.greenwoodmap.com
>



-- 
David Zwarg
Software Developer
Avencia Incorporated
www.avencia.com