[postgis-devel] pgraster: st_resample error

[Bborie Park]

Hey Tom,

Regina asked me about a similar concern regarding tiles after they
were projected so I did some digging yesterday.  The reprojected
tile's extent doesn't matter as long as the tile data is spatially
correct.

I've been double-checking the transformed rasters vs the reference
rasters using qgis.  Though the extent of the transformed tile doesn't
match that of the source tile, the pixel data lines up correctly when
looking for important features such as edges of the data and areas
where I know that the data should be different (mountain ranges vs
valleys).

-bborie

On Wed, Dec 28, 2011 at 12:52 AM, Tom van Tilburg
<tom.van.tilburg at gmail.com> wrote:
> Hi Bborie,
>
> What's the best way to check that?
>
> Another thing I noticed:
> Using gdalwarp in qgis from 28992 to 900913 gives me this 20 km offset.
> However, when I manually force the warped image to be shown in 3875
> projection, it shows up well. Using gdalinfo on the warped image it strikes
> me that there is no information on the 'authority' of the PROJCS (should be
> 900913). (see below)
>
> Cheers,
>  Tom
>
>
> Driver: GTiff/GeoTIFF
> Files: ahn1_900913.asc
> Size is 788, 690
> Coordinate System is:
> PROJCS["Google Maps Global Mercator",
>    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["Mercator_1SP"],
>    PARAMETER["central_meridian",0],
>    PARAMETER["scale_factor",1],
>    PARAMETER["false_easting",0],
>    PARAMETER["false_northing",0],
>    UNIT["metre",1,
>        AUTHORITY["EPSG","9001"]]]
> Origin = (656440.434583136229776,6806151.070541447028518)
> Pixel Size = (8.117405487721264,-8.117405487721264)
> Metadata:
>  AREA_OR_POINT=Area
> Image Structure Metadata:
>  INTERLEAVE=BAND
> Corner Coordinates:
> Upper Left  (  656440.435, 6806151.071) (  5d53'48.86"E, 52d13'10.86"N)
> Lower Left  (  656440.435, 6800550.061) (  5d53'48.86"E, 52d11'19.57"N)
> Upper Right (  662836.950, 6806151.071) (  5d57'15.72"E, 52d13'10.86"N)
> Lower Right (  662836.950, 6800550.061) (  5d57'15.72"E, 52d11'19.57"N)
> Center      (  659638.692, 6803350.566) (  5d55'32.29"E, 52d12'15.23"N)
> Band 1 Block=788x2 Type=Float32, ColorInterp=Gray
>
>
>
> On 28-12-2011 1:57, Bborie Park wrote:
>>
>> Hey Tom,
>>
>> I'm basically wondering if for a latitude/longitude, the value at that
>> coordinate is correct regardless of projection.
>>
>> -bborie
>>
>> On Tue, Dec 27, 2011 at 8:06 AM, Tom van Tilburg
>>
>
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