[gdal-dev] gdalinfo coordinates problem?

[Etienne Tourigny]

I noticed that qgis-2.0 also has a problem with this file, but places it
around 54 degrees west longitude (if using on-the-fly reprojection to
WGS84).

The CRS is different from that identified by gdal (the lon_0, units and
datum are different)

qgis:
+proj=lcc +lat_1=40.96666666666667 +lat_2=39.93333333333333
+lat_0=39.33333333333334 +lon_0=-77.75 +x_0=600000 +y_0=0 +ellps=GRS80
+towgs84=0,0,0,0,0,0,0 +units=m +no_defs


gdal:
PROJ.4 : '+proj=lcc +lat_1=40.96666666666667 +lat_2=39.93333333333333
+lat_0=39.33333333333334 +lon_0=-77.75 +x_0=1968500 +y_0=0 +datum=NAD83
+units=us-ft +no_defs '

OGC WKT :
PROJCS["NAD_1983_StatePlane_Pennsylvania_South_FIPS_3702_Feet",
    GEOGCS["NAD83",
        DATUM["North_American_Datum_1983",
            SPHEROID["GRS 1980",6378137,298.2572221010002,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","6269"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4269"]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["standard_parallel_1",40.96666666666667],
    PARAMETER["standard_parallel_2",39.93333333333333],
    PARAMETER["latitude_of_origin",39.33333333333334],
    PARAMETER["central_meridian",-77.75],
    PARAMETER["false_easting",6458320.416666666],
    PARAMETER["false_northing",0],
    UNIT["us_survey_feet",0.3048006096012192],
    AUTHORITY["EPSG","32129"]]




On Fri, Jan 17, 2014 at 8:37 PM, Even Rouault
<even.rouault at mines-paris.org>wrote:

> Le vendredi 17 janvier 2014 21:28:35, Reynolds, Scott a écrit :
> > Hi,
> >
> > I've downloaded several DEMs (e.g 27002570PAS_dem.zip) from
> > ftp://pamap.pasda.psu.edu/pamap_lidar/cycle1/DEM/South/2008/20000000/.
> > Gdalinfo is reporting the corner coordinates to be in the vicinity of  91
> > degrees 31 minutes west longitude which should be more like 75 degrees 36
> > minutes west longitude.  Can someone explain what is happening here?
>
> GeoTIFF support for non-meter linear units has been a major source of
> headaches in GDAL / libgeotiff. People will appreciate looking at
> frmts/gtiff/gt_wkt_srs.cpp
>
> I'm not sure if that GeoTIFF file is correct or not regarding the values
> of the
> false easting/northing with respect to the GeoTIFF spec (many in the wild
> are
> broken), but when looking at what happens, I noticed that a transformation
> from meters to feet happened twice. The attached patch fixes that (and the
> corner coordinates are around 75°), but I'm not sure if it is completely
> correct in all cases.
>
> You should likely create a GDAL Trac ticket with your report and the patch,
> but I'm not sure who will dare hurting his head against this wall...
>
> Even
>
> >
> > Thanks,
> > Scott
>
> --
> Geospatial professional services
> http://even.rouault.free.fr/services.html
>
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