[Qgis-user] projecting and "un-projecting"

[Don MacQueen]

I have loaded a shapefile into QGis. The shapefile is in lat/long and 
is not projected. Indeed, its .prj file contains:

   GEOGCS["GCS_North_American_1983",
   DATUM["D_North_American_1983",
   SPHEROID["GRS_1980",6378137,298.257222101]],
   PRIMEM["Greenwich",0],
   UNIT["Degree",0.017453292519943295]]

I have learned how to apply an on the fly projection, and have 
learned that if I use "Save as Shapefile" and apply the same 
projection in the Save As process, the new shapefile is in the 
projected coordinate system.

Suppose, however, that someone provides me with a shapefile that is 
already projected, using the same projection I applied above.

For example, the .prj file contains:

   PROJCS["NAD_1983_StatePlane_New_York_Long_Island_FIPS_3104_Feet",
   GEOGCS["GCS_North_American_1983",
   DATUM["D_North_American_1983",
   SPHEROID["GRS_1980",6378137.0,298.257222101]],
   PRIMEM["Greenwich",0.0],
   UNIT["Degree",0.0174532925199433]],

   PROJECTION["Lambert_Conformal_Conic"],
   PARAMETER["Central_Meridian",-74.0],
   PARAMETER["False_Easting",984250.0],
   PARAMETER["False_Northing",0.0],
   PARAMETER["Latitude_Of_Origin",40.16666666666666],
   PARAMETER["Standard_Parallel_1",40.66666666666666],
   PARAMETER["Standard_Parallel_2",41.03333333333333],
   UNIT["Foot_US",0.3048006096012192]]

I would like to be able do the reverse operation. That is, 
"unproject" this shapefile and use the Save as Shapefile dialog to 
make a copy that is in lat/long.

I haven't found out how to do this, and would appreciate some help doing it.

Thanks
-Don

p.s., if anyone is curious as to why, the actual application is to 
load the projected shapefile, add a new vector layer as a shapefile 
(such as a polygon), and save the new layer as a shapefile in 
un-projected coordinates.
-- 
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Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
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