[gdal-dev] GMLJP2 question

[Frank Warmerdam]

Scott,

Examining gdal/gcore/gdaljp2metadata.cpp it is clear the code
believe that the GML rectified grid origin is the center of the top
left pixel and adjusts accordingly.  This is something we worked on
pretty carefully during the GMLJP2 interoperability experiment with
OGC a few years ago so I find it hard to believe that GDAL is
wrote relative to what I and Lizardtech understood the specifiction
to be at the time.

I would suggest you ask the producer to justify their approach.

Best regards,

On Thu, Nov 17, 2011 at 2:47 PM, Reynolds, Scott <scott at agi.com> wrote:
> Hi,
>
>
>
> I have a JP2 image whose extent is supposed to be from (0E deg , 0N deg) to
> (10E deg, 10N deg) but gdalinfo (from FWTools 2.4.7) is reporting extents
> that are off by 0.5 pixel north and west.  The GML identifies the origin of
> the image as (0E deg, 10N deg).  My understanding is that GDAL automatically
> adjusts to account for pixel center vs. pixel corner format differences and
> always reports pixel corners.  What I’m not sure of is whether GML thinks
> the origin is centered on the top left pixel or at the top left corner of
> the top left pixel.
>
>
>
> Can someone tell me whether I need to submit a bug against:
>
>
>
> 1)      GDAL
>
> 2)      JP2 writer
>
> 3)      Me
>
>
>
> Thanks,
>
> Scott
>
>
>
> Driver: JP2ECW/ERMapper JPEG2000
>
> Files: e:\TestData\junk.jp2
>
> Size is 256, 256
>
> Coordinate System is:
>
> GEOGCS["WGS 84",
>
>     DATUM["WGS_1984",
>
>         SPHEROID["WGS 84",6378137,298.257223563,
>
>             AUTHORITY["EPSG","7030"]],
>
>         AUTHORITY["EPSG","6326"]],
>
>     PRIMEM["Greenwich",0,
>
>         AUTHORITY["EPSG","8901"]],
>
>     UNIT["degree",0.01745329251994328,
>
>         AUTHORITY["EPSG","9122"]],
>
>     AUTHORITY["EPSG","4326"],
>
>     AXIS["Latitude",NORTH],
>
>     AXIS["Longitude",EAST]]
>
> GeoTransform =
>
>   10.01953125, 0, -0.0390625
>
>   -0.01953125, 0.0390625, 0
>
> Corner Coordinates:
>
> Upper Left  (  10.0195313,  -0.0195313) ( 10d 1'10.31"E,  0d 1'10.31"S)
>
> Lower Left  (   0.0195313,  -0.0195313) (  0d 1'10.31"E,  0d 1'10.31"S)
>
> Upper Right (  10.0195313,   9.9804688) ( 10d 1'10.31"E,  9d58'49.69"N)
>
> Lower Right (   0.0195313,   9.9804688) (  0d 1'10.31"E,  9d58'49.69"N)
>
> Center      (   5.0195313,   4.9804688) (  5d 1'10.31"E,  4d58'49.69"N)
>
> Band 1 Block=256x1 Type=Byte, ColorInterp=Red
>
>   Overviews: arbitrary
>
> Band 2 Block=256x1 Type=Byte, ColorInterp=Green
>
>   Overviews: arbitrary
>
> Band 3 Block=256x1 Type=Byte, ColorInterp=Blue
>
>   Overviews: arbitrary
>
> Band 4 Block=256x1 Type=Byte, ColorInterp=Undefined
>
>   Overviews: arbitrary
>
>
>
> The GML embedded in the file is
>
>
>
> <gml:FeatureCollection
>
> xmlns:gml="http://www.opengis.net/gml"
>
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>
> xsi:schemaLocation="http://www.opengis.net/gml
> http://www.math.ubc.ca/~burggraf/gml/gml4jp2.xsd">
>
> <gml:boundedBy>
>
>   <gml:Null>withheld</gml:Null>
>
> </gml:boundedBy>
>
> <gml:featureMember>
>
>   <gml:RectifiedGridCoverage dimension="2" gml:id="RGC0001">
>
>    <gml:rectifiedGridDomain>
>
>     <gml:RectifiedGrid dimension="2">
>
>      <gml:limits>
>
>      <gml:GridEnvelope>
>
>        <gml:low>0 0</gml:low>
>
>        <gml:high>255 255</gml:high>
>
>       </gml:GridEnvelope>
>
>      </gml:limits>
>
>      <gml:axisName>x</gml:axisName>
>
>      <gml:axisName>y</gml:axisName>
>
>      <gml:origin>
>
>       <gml:Point gml:id="P0001" srsName="urn:ogc:def:crs:EPSG::4326">
>
>        <gml:pos>0.0000000000000 10.0000000000000</gml:pos>
>
>       </gml:Point>
>
>      </gml:origin>
>
>      <gml:offsetVector srsName="urn:ogc:def:crs:EPSG::4326">0.0390625000000
> -0.0000000000000</gml:offsetVector>
>
>      <gml:offsetVector srsName="urn:ogc:def:crs:EPSG::4326">-0.0000000000000
> -0.0390625000000</gml:offsetVector>
>
>     </gml:RectifiedGrid>
>
>    </gml:rectifiedGridDomain>
>
>   </gml:RectifiedGridCoverage>
>
> </gml:featureMember>
>
> </gml:FeatureCollection>
>
>
>
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