[Proj] hammer parameters?

William Kyngesburye woklist at kyngchaos.com
Thu Jan 13 12:01:12 EST 2011

On Jan 12, 2011, at 5:33 PM, Frank Warmerdam wrote:

> Folks,
> For what it is worth, it is possible to embed a literal PROJ.4 string
> in GDAL/OGR WKT in which case that will be used as the translation to
> PROJ.4 format.
> eg.
> PROJCS["UTM Zone 11, Northern Hemisphere",
>     GEOGCS["WGS 84",
>         DATUM["WGS_1984",
>             SPHEROID["WGS 84",6378137,298.257223563,
>                 AUTHORITY["EPSG","7030"]],
>             TOWGS84[0,0,0,0,0,0,0],
>             AUTHORITY["EPSG","6326"]],
>         PRIMEM["Greenwich",0,
>             AUTHORITY["EPSG","8901"]],
>         UNIT["degree",0.0174532925199433,
>             AUTHORITY["EPSG","9108"]],
>         AUTHORITY["EPSG","4326"]],
>     PROJECTION["Transverse_Mercator"],
>     PARAMETER["latitude_of_origin",0],
>     PARAMETER["central_meridian",-117],
>     PARAMETER["scale_factor",0.9996],
>     PARAMETER["false_easting",500000],
>     PARAMETER["false_northing",0],
>     UNIT["Meter",1],
>     EXTENSION["PROJ4","+proj=utm +zone=11 +datum=WGS84 +wktext"]]
> When passing proj.4 strings to GDAL utilities which take
> PROJ.4 as input you can include the +wktext option to force
> literal inclusion of the PROJ.4 string.  For projections
> completely not supported by GDAL you will need to create
> WKT with some sort of fake projection (perhaps just use
> the above and update the EXTENSION[] portion.
I tried this a few months ago for another unsupported projection in GDAL with no luck.  Doesn't work here either.  Quote from Evan Rouault:

"+wktext cannot help when OSR doesn't recognize the projection. It only helps 
to keep the extra options that OSR doesn't handle by itself."

So, if GDAL doesn't support ob_tran, +wktext won't help.

William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>

First Pogril: Why is life like sticking your head in a bucket filled with hyena offal?
Second Pogril: I don't know.  Why IS life like sticking your head in a bucket filled with hyena offal?
First Pogril: I don't know either.  Wretched, isn't it?

-HitchHiker's Guide to the Galaxy

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