[gdal-dev] AREA_OR_POINT vs GDALMD_AREA_OR_POINT

[Even Rouault]

> 
> Glad to not do, but than I'm left with nothing. If I do instead as you say
> 
>      GDALSetMetadataItem(hDstDS, GDALMD_AREA_OR_POINT, "Point", NULL);
> 
> which than equivalent to
> 
>      GDALSetMetadataItem(hDstDS, "AREA_OR_POINT", "Point", NULL);
> 
> than, as I showed before and contrary to your python examples, the
> GDALSetMetadataItem() is not working in our code.
> 
> > On which dataset do you this : a GTiff dataset ? Opened in update mode ?
> 
> No, not update mode. It's dataset filled an empty MEM. See (lines #167
> and after)
> 
> http://gmtrac.soest.hawaii.edu/projects/gmt/repository/entry/branches/5.2.0/
> src/gmt_gdalwrite.c

Well, I suppose that your local copy of the code use GDALMD_ARE_OR_POINT 
unquoted...

I've tried a simplified version of your code and it works for me. Do you use a 
recent enough version of GDAL ?

from osgeo import gdal
from osgeo import osr
mem_ds = gdal.GetDriverByName('Mem').Create('mem', 1, 1)
mem_ds.SetGeoTransform([10,1,0,100,0,-1])
sr = osr.SpatialReference()
sr.ImportFromEPSG(32631)
mem_ds.SetProjection(sr.ExportToWkt())
mem_ds.SetMetadataItem('AREA_OR_POINT', 'Point')
gtiff_ds = gdal.GetDriverByName('GTiff').CreateCopy('out.tif', mem_ds)
gtiff_ds = None

Note: for AREA_OR_POINT to be taken into account in GeoTiff, you need to define 
both a geotransform and a SRS.

$ gdalinfo out.tif
Driver: GTiff/GeoTIFF
Files: out.tif
Size is 1, 1
Coordinate System is:
PROJCS["WGS 84 / UTM zone 31N",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",3],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","32631"]]
Origin = (10.000000000000000,100.000000000000000)
Pixel Size = (1.000000000000000,-1.000000000000000)
Metadata:
  AREA_OR_POINT=Point
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (      10.000,     100.000) (  1d29'19.16"W,  0d 0' 3.25"N)
Lower Left  (      10.000,      99.000) (  1d29'19.16"W,  0d 0' 3.21"N)
Upper Right (      11.000,     100.000) (  1d29'19.12"W,  0d 0' 3.25"N)
Lower Right (      11.000,      99.000) (  1d29'19.12"W,  0d 0' 3.21"N)
Center      (      10.500,      99.500) (  1d29'19.14"W,  0d 0' 3.23"N)
Band 1 Block=1x1 Type=Byte, ColorInterp=Gray


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