[postgis-devel] pgraster: st_resample error

[Bborie Park]

I plan on posting there after I do some experimenting.  The 20KM north
or south is probably coming from the plus or minus used for scale-Y.
I believe GDAL defaults to a negative value for scale-Y while PostGIS
Raster will use the scale-Y of the input raster.

-bborie

On Fri, Dec 23, 2011 at 7:58 AM, Tom van Tilburg
<tom.van.tilburg at gmail.com> wrote:
> Hi Bborie,
>
> thanks.
> I keep an eye on the ticket but it's a bit beyond my abilities to understand
> all of it ;-)
>
> My 2 cents however on Evens post:
>
> The errors in the amersfoort (28992) projecten have been known for a long
> time, that's not what bothers me at the moment.
>
> From all the small errors in the google-mercator projections (I think there
> are 4 around, all slightly different) I have never seen 20 km. error in the
> offset. It more feels to me that numbers have been swapped instead of
> miscalculated.
> The fact that postgis moves it 20 km south while gdal_warp moves it 20 km
> the opposite direction is also puzzling. What could that indicate?
>
> I'll keep an eye on the gdal list as well. Are you posting there?
>
> Cheers,
>  Tom
>
>
>
> On 23-12-2011 16:38, Bborie Park wrote:
>>
>> Tom,
>>
>> When you have the chance, can you look at ticket #1402?
>>
>> http://trac.osgeo.org/postgis/ticket/1402
>>
>> Even from the GDAL project responded with a thorough explanation of
>> what's causing the drift.  I'm still digesting his explanation and
>> will see what can be done to improve the projection handling in
>> PostGIS Raster.  Currently, we use the value in the "srtext" column of
>> spatial_ref_sys, but it looks like we may have better luck using the
>> "proj4text" column and have GDAL process it through their mechanisms.
>>
>> -bborie
>>
>>
>
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