[gdal-dev] gdal_merge / negative size

[Chaitanya kumar CH]

Ghislain,

It may be counter intuitive to have smaller y-coordinate for lower

On Tue, Nov 2, 2010 at 12:34 AM, Ghislain Picard <
ghislain.picard at lgge.obs.ujf-grenoble.fr> wrote:

>
> Hi All,
>
> I have an image having y-coordinate increasing in the downward direction.
> To display the image, the pixel size is -1000 on the y-axis (see ENVI
> header file below). This works perfectly except in gdal_merge when use to
> clip the raster (using QGis GdalTools(s plugin for instance).
>
> For instance:
>
> gdal_merge.py -ul_lr
> 95926.7879548 490702.415307 2036599.49812 -1014610.25721
>
> fails because the output image size calculated by gdal_merge is negative.
> Inverting the  y-coordinates like this:
>
> gdal_merge.py -ul_lr
> 95926.7879548 -1014610.25721 2036599.49812 490702.415307
>
> works but it is counter-intuitive as the lower-right point should have a
> smaller y-coordinate than the upper-left point.
> It seems the size calculated by gdal_merge does not account for the sign of
> the pixel size.
>
> Ghislain
>
>
>
>
> ENVI
> description = {
>   File Imported into ENVI.}
> samples = 5601
> lines   = 5601
> bands   = 1
> header offset = 0
> file type = ENVI Standard
> data type = 4
> interleave = bsq
> sensor type = Unknown
> byte order = 0
> no data = 0
> wavelength units = Unknown
> map info = {Polar Stereographic, 1, 1, -2800500, -2800500, 1000,
> -1000,WGS-84}
> projection info = {31, 6378137, 6356752.314245179, -71, 0, 0, 0,WGS-84,
> Polar Stereographic}
>
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
Best regards,
Chaitanya kumar CH.
/tʃaɪθənjə/ /kʊmɑr/
+91-9494447584
17.2416N 80.1426E
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20101102/1d47df04/attachment.html