[gdal-dev] 4th band as ALPHA on warp

[Daniele Romagnoli]

Hi Even,
my usual question would be: any plan to backport it? :-)

Cheers,
Daniele





On Sun, Aug 7, 2016 at 10:38 PM, Even Rouault <even.rouault at spatialys.com>
wrote:

> Le dimanche 07 août 2016 19:20:05, Even Rouault a écrit :
> > Le samedi 06 août 2016 15:20:54, Fernando Ribeiro a écrit :
> > > Dear list,
> > >
> > > Currently we are working with 4 band tifs, first 3 bands as normal RBG
> > > and the 4th as IR. On performing a warp operation from and to a VRT,
> > > GDAL seems considering the 4th band as alpha, resulting in full black
> > > pixels if 4th band value =0.
> >
> > gdalwarp will consider the 4th band as alpha... only if it is effectively
> > tagged as alpha in the source. You can check it with gdalinfo
> >
> > > Some attempts were made to solve this issue, so far without success:
> > >
> > > - Using the warp creation options PHOTOMETRIC=RGB and ALPHA=NO
> >
> > This will not influence the warping kernel.
> >
> > > - Manually editing the source VRT and replace Alpha color
> interpretation
> > > to Undefined
> >
> > This one should work. Strange that this doesn't work for you.
> >
> > > Does anyone have more suggestions?
>
> I've just committed an improvement in trunk: "gdalwarp: add a -nosrcalpha
> option to wrap the alpha band as a regular band and not as the alpha band"
>
> > >
> > > Thank you
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
==
GeoServer Professional Services from the experts! Visit
http://goo.gl/it488V for more information.
==

Ing. Daniele Romagnoli
Senior Software Engineer

GeoSolutions S.A.S.
Via di Montramito 3/A
55054  Massarosa (LU)
Italy
phone: +39 0584 962313
fax:      +39 0584 1660272

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

-------------------------------------------------------

*AVVERTENZE AI SENSI DEL D.Lgs. 196/2003*

Le informazioni contenute in questo messaggio di posta elettronica e/o
nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
loro utilizzo è consentito esclusivamente al destinatario del messaggio,
per le finalità indicate nel messaggio stesso. Qualora riceviate questo
messaggio senza esserne il destinatario, Vi preghiamo cortesemente di
darcene notizia via e-mail e di procedere alla distruzione del messaggio
stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od
utilizzarlo per finalità diverse, costituisce comportamento contrario ai
principi dettati dal D.Lgs. 196/2003.



The information in this message and/or attachments, is intended solely for
the attention and use of the named addressee(s) and may be confidential or
proprietary in nature or covered by the provisions of privacy act
(Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction,
copying, distribution, or either dissemination, either whole or partial, is
strictly forbidden except previous formal approval of the named
addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the
information in this message that has been received in error. The sender
does not give any warranty or accept liability as the content, accuracy or
completeness of sent messages and accepts no responsibility  for changes
made after they were sent or for other risks which arise as a result of
e-mail transmission, viruses, etc.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20160808/b64a66e4/attachment.html>