[Gdal-dev] *solved*: Black border after changing projection: possible to remove this?

[wqual]

Hello Vincent!
Thank you very much for your message. This trick works perfect! Great!

Best regards,
Wolfgang

----8<-----------------------
Am Mittwoch 19 Juli 2006 pH:22:10 vormittags schrieb Vincent Schut:
> -------- Original Message --------
> From: wqual <wolfgang.qual at gmx.net>
> To: gdal-dev at lists.maptools.org
> Subject: [Gdal-dev] Black border (null value) after changing
> projection:    possible to remove this?
> Date: 07/19/2006 09:27 AM
>
> > Hi gdal-list,
> > Recently, I had to change the projection of some satellite tiles. I used
> > gdalwarp for this purpose and it worked perfectly.
> > The only thing is: as the tiles were rotated a little bit, black
> > triangles (representing null-values) appear because of the rotation).
> > When I load these tiles in one view or a mapserver map, these black
> > triangles overlay adjacent tiles a little bit.
> > Therefore my question:
> > Is there a possiblity to remove these "triangles" resp.: can I define
> > them as transparent? I would like to put them into a mapserver map using
> > gdaltindex.
> >
> > I would be grateful for some comments about this.
>
> You can do this in mapserver by defining an OFFSITE <rgb color>
> parameter in your raster layers in your mapfile. This works as long as
> those triangles are really constant of color, or in other words: they'd
> better not be jpegs because the jpeg compression will add noise to your
> nice black areas. We've been using this trick extensively to overlay
> raster imagery (landsat scenes, etc) on other data using mapserver,
> including raster on raster. It works perfectly. See the mapserver
> mapfile documentation (layer object, offsite parameter) for more info.
>
> Regards,
> Vincent.
>
> > Best regards,
> > Wolfgang
> >
> >
> >
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