[gdal-dev] ​Re: Raster origin coodinates in file header

[Piero Campalani]

Adrien,

OGC in its GML standard document -- of course in line with ISO --
recommends that:

* "When a grid point is used to represent a sample space (e.g. image
pixel), the grid point represents the center of the sample space (see ISO
19123:2005, 8.2.2)"*. ​

​GML encodes the locations of a raster/gridded-coverage by means of a grid
of ​0D points.

​You can always put your raster origin wherever you want, i.e. in whatever
corner you prefer.
Alas, there's no way -- that I am aware of -- to specify what is the shape
of a measurement footprint/sample-space, nor to say if the footprint
surrounds the point-geometry equally (point is pixel-centre) or some other
way (point is pixel-upper-left-corner?).

Hence raster creators should probably stick to this recommended encoding
until standards do not offer more freedom on this :)

​@seeAlso
​http://rasdaman.org/wiki/PetascopeSubsets
http://rasdaman.org/ticket/680​

-
​Piero !​
​

On 29 June 2015 at 21:00, <gdal-dev-request at lists.osgeo.org> wrote:

> Date: Mon, 29 Jun 2015 11:12:11 +0200
> From: Adrien ANDR? <adr.andre at laposte.net>
> To: gdal-dev at lists.osgeo.org
> Subject: [gdal-dev] Raster origin coodinates in file header
> Message-ID: <55910BEB.2030307 at laposte.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Dear list,
>
> opening 2 rasters with different resolutions i noticed a shift.
>
> Asking our imagery provider, i was told the origin coordinates they
> store in image header (JP2 files) are those of the top left pixel center.
>
> GDAL reads origin coordinates as the top left pixel top left corner
> coordinates, as i'm used to.
>
>
> Of course, i fixed my problem, the hacky way, playing with
> gdal_translate a_ullr option, but:
>
> How to deal with this?
> How not to worry about georeferencing each time i load a raster file?
> Is there any OGC recommendation about origin coordinates storage?
>
>
> Thanking you in advance,
>
> Regards,
>
> Adrien
>
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