On 11 avr. 07, at 05:54, anhtin wrote:
>
> hi all
> I have Point (194, 569) is corrdinate pixel i want convert to
> corrdinate
> spatial on postgis
> How can i do that ????
> --
> View this message in context:
http://www.nabble.com/Convert-
> Corrdinate-Pixel-to-Corrdinate-Spatial-tf3557178.html#a9932812
> Sent from the PostGIS - User mailing list archive at Nabble.com.
>
Hi,
This is more a gdal thing, but there is no simple tool to do that.
But what you can do if you want to keep most of the work in postgis,
is to manually convert your pixel coordinates in your image spatial
coordinates system, and then convert it to your final coordinates
system (Lat Lon for example) inside postgis using Transform().
Assuming that your image projection use a orthogonal coordinates
system (it should), converting your pixel coordinates xp, yp in your
image spatial coordinates system is easy, for an image that have
x1,y1 for bottom left corner and x2,y2 for top left corner (get it
with gdalinfo) you just have to do :
x = xp/width * (x2 - x1) + x1
y = yp/height * (y2 - y1) + y1
then you can do
SELECT Transform(AsEWKT("SRID=<IMAGE_SRID>;POINT(<x>, <y>)"),
<TARGET_SRID>);
to let postgis calculate the complicated thing.
But your message wasn't very clear, your may just need the first part
of my response :)
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