[gdal-dev] [PATCH v2] Support Mercator_2SP in GeoTIFF
Trent Piepho
tpiepho at gmail.com
Tue Nov 19 18:29:25 PST 2013
Antii,
Thank you for the testing. It looks like Arc/GIS works while FME and
Intergraph don't.
That file had both StdParallel1 and ScaleAtNatOrigin defined.
I've uploaded two new files. This one has only StdParallel1 defined with
no ScaleAtNatOrigin.
https://drive.google.com/file/d/0BybuTedE9CLxRnNlNUl2Zm5JRzg/edit?usp=sharing
This file has the lat_ts stored in NatOriginLat and no ScaleAtNatOrigin
defined.
https://drive.google.com/file/d/0BybuTedE9CLxMzltYlBFWU51RzA/edit?usp=sharing
I think the latter might have better compatibility. Yet it seems to
clearly be the incorrect way to do it.
On Mon, Nov 18, 2013 at 4:54 AM, Antti Castrén <antti.castren at iki.fi> wrote:
> Hi Trent,
>
> The chart opens in ArcMap (ArcGIS 10.0) well, and it is in right
> location (Seattle).
>
> Relevant properties of the file as seen by ArcGIS:
> Cell Size: 240.003787, 240.003787
> Extent
> Top:4143530.20898
> Left: -9278434.53415
> Right: -9165872.75807
> Bottom: 3984167.69444
> Spatial Reference: Global Mercator
> Linear Unit: Meter
> false_easting: 0
> false_northing: 0
> central_meridian: 0
> standard_parallel_1: 47.667
> Datum: D_North_American_1983
>
>
> I opened the file in FME Data Inspector (FME Desktop 2013 SP1) also.
> It did not read the latitude of true scale from the
> ProjStdParallel1GeoKey as you can see from the following parameters.
> Therefore it places the chart to NE Georgia/NW South Carolina as if
> the latitude of true scale was the Equator.
>
> <FME Parameters>
> Coordinate System Parameters
> CS_NAME: _FME_0
> DESC_NM: Global Mercator
> DT_NAME: NAD83
> PROJ: MRCAT
> UNIT: METER
>
> Datum Parameters
> DESC_NM: NAD 1983, Alaska, Canada,Continental US,Mexico,Central America
> ELLIPSOID: GRS1980
> SOURCE: US Defense Mapping Agency, TR-8350.2-B, August 1993
> USE: NAD83
>
> Ellipsoid Parameters
> DESC_NM: Geodetic Reference System of 1980
> E_RAD: 6378137
> P_RAD: 6356752.3141403478
> SOURCE: Stem, L.E., Jan 1989, State Plane Coordinate System of 1983
>
> OGC WKT Description
> PROJCS["Global Mercator",
> GEOGCS["NAD83",
> DATUM["North_American_Datum_1983",
> SPHEROID["Geodetic Reference System of
> 1980",6378137,298.2572221008916,
> AUTHORITY["EPSG","7019"]],
> AUTHORITY["EPSG","6269"]],
> PRIMEM["Greenwich",0],
> UNIT["degree",0.0174532925199433],
> AUTHORITY["EPSG","4269"]],
> PROJECTION["Mercator_1SP"],
> PARAMETER["central_meridian",0],
> PARAMETER["scale_factor",1],
> PARAMETER["false_easting",0],
> PARAMETER["false_northing",0],
> UNIT["METER",1]]
>
> Esri WKT Description
>
> PROJCS["Global_Mercator",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["Geodetic_Reference_System_of_1980",6378137,298.2572221008916]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Mercator"],PARAMETER["central_meridian",0],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["Meter",1],PARAMETER["standard_parallel_1",0.0]]
> </FME Parameters>
>
> Intergraph's Geomedia Professional recognises the file as GeoTIFF, but
> the chart appears to be in the same false place as with FME.
>
> If you want, I could update the file's georeferencing by FME and
> Geomedia so that location is correct. Then I could send listgeo
> information or even put the actual files available if desired.
>
> The goal is, of course, to get various software vendors to use the
> GeoTIFF-information the same way. Hopefully the common way would also
> be logically correct, but I guess that's too much to ask.
>
> Best regards,
>
> Antti
>
>
> Here is the listgeo info from the original file for those who are
> interested:
>
> Geotiff_Information:
> Version: 1
> Key_Revision: 1.0
> Tagged_Information:
> ModelTiepointTag (2,3):
> 0 0 0
> -9278434.53 4143530.21 0
> ModelPixelScaleTag (1,3):
> 240.003787 240.003787 0
> End_Of_Tags.
> Keyed_Information:
> GTModelTypeGeoKey (Short,1): ModelTypeProjected
> GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
> GTCitationGeoKey (Ascii,16): "Global Mercator"
> GeographicTypeGeoKey (Short,1): GCS_NAD83
> GeogCitationGeoKey (Ascii,6): "NAD83"
> GeogAngularUnitsGeoKey (Short,1): Angular_Degree
> GeogSemiMajorAxisGeoKey (Double,1): 6378137
> GeogInvFlatteningGeoKey (Double,1): 298.257222
> Unknown-2062 (Double,3): 0 0 0
> ProjectedCSTypeGeoKey (Short,1): User-Defined
> ProjectionGeoKey (Short,1): User-Defined
> ProjCoordTransGeoKey (Short,1): CT_Mercator
> ProjLinearUnitsGeoKey (Short,1): Linear_Meter
> ProjStdParallel1GeoKey (Double,1): 47.667
> ProjNatOriginLongGeoKey (Double,1): 0
> ProjNatOriginLatGeoKey (Double,1): 0
> ProjFalseEastingGeoKey (Double,1): 0
> ProjFalseNorthingGeoKey (Double,1): 0
> ProjScaleAtNatOriginGeoKey (Double,1): 1
> End_Of_Keys.
> End_Of_Geotiff.
> Projection Method: CT_Mercator
> ProjNatOriginLatGeoKey: 0.000000 ( 0d 0' 0.00"N)
> ProjNatOriginLongGeoKey: 0.000000 ( 0d 0' 0.00"E)
> ProjScaleAtNatOriginGeoKey: 1.000000
> ProjFalseEastingGeoKey: 0.000000 m
> ProjFalseNorthingGeoKey: 0.000000 m
> GCS: 4269/NAD83
> Datum: 6269/North American Datum 1983
> Ellipsoid: 7019/GRS 1980 (6378137.00,6356752.31)
> Prime Meridian: 8901/Greenwich (0.000000/ 0d 0' 0.00"E)
> Projection Linear Units: 9001/metre (1.000000m)
> Corner Coordinates:
> Upper Left (-9278434.534, 4143530.209)
> Lower Left (-9278434.534, 3984167.694)
> Upper Right (-9165872.758, 4143530.209)
> Lower Right (-9165872.758, 3984167.694)
> Center (-9222153.646, 4063848.952)
>
>
> 2013/11/14 Trent Piepho <tpiepho at gmail.com>:
> > It looks like arcgis does not support Mercator_1SP in geotiff files.
> > It just ignores the scale factor and uses 1.0. Which means in GDAL
> > and libgeotiff as they are now, there is no way to export Mercator
> > projections that don't have a scale of 1.0 to arcgis.
> >
> > ArcGIS does support Mercator_2SP, but instead of placing the latitude
> > of true scale in ProjStdParallel1GeoKey, it uses
> > ProjNatOriginLatGeoKey. Which seems to be plainly wrong, yet that's
> > what it does.
> >
> > I wonder if ESRI used libgeotiff? With unpatched libgeotiff, the only
> > way to get a latitude from a Mercator geotiff it to use one of the
> > origin latitude GeoKeys. It's not correct, but it does allow one to
> > stick the number in the file and get it back out without having to
> > modify or understand any libgeotiff code.
> >
> > It's possible that ArcGIS supports getting the latitude of true scale
> > from ProjStdParallel1GeoKey, even it it doesn't store it there.
> > Antii, could you test this file with ArcGIS?
> >
> >
> https://drive.google.com/file/d/0BybuTedE9CLxak9iakZRTC00cHM/edit?usp=sharing
> >
> > Pick file->download to get the geotiff file.
> >
> > It should have projection information like this:
> > PROJECTION["Mercator_2SP"],
> > PARAMETER["standard_parallel_1",47.667],
> > PARAMETER["central_meridian",0],
> > PARAMETER["false_easting",0],
> > PARAMETER["false_northing",0],
> > UNIT["metre",1,
> > AUTHORITY["EPSG","9001"]]]
> > Origin = (-9278434.534151820465922,4143530.208984711207449)
> > Pixel Size = (240.003786961970206,-240.003786961970206)
> > Corner Coordinates:
> > Upper Left (-9278434.534, 4143530.209) (123d32'26.22"W, 48d23'56.59"N)
> > Lower Left (-9278434.534, 3984167.694) (123d32'26.22"W, 46d57'58.64"N)
> > Upper Right (-9165872.758, 4143530.209) (122d 2'30.76"W, 48d23'56.59"N)
> > Lower Right (-9165872.758, 3984167.694) (122d 2'30.76"W, 46d57'58.64"N)
> > Center (-9222153.646, 4063848.952) (122d47'28.49"W, 47d41'15.43"N)
>
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