Hi Rich,
I think that inferring the threshold on the coverage could be slow (for
example for BigTiff data). In JAI-EXT we introduced the concept of NoData,
which will be used by the Mosaic operation instead of the old
threshold value.
Regards,
Nicola Lagomarsini.
2015-02-03 22:22 GMT+01:00 Rich Fecher <rfec...@gmail.com>:
> We've been using the geotools' resample operation to generally resize
> rasters and have run into an issue. We have multiple bands with the double
> data type and in the situation where the transform resolves to an identity
> transform the resulting mosaic operation ends up masking some values. The
> Resampler2D code sets null for sourceROI and sourceThreshold for the
> MosaicDescriptor parameters which results in the default sourceThreshold of
> 1.0 being used. The resulting MosaicOpImage then sets all values that are
> less than 1.0 to the background value.
>
> Here's where the resampler uses the default parameters:
>
> https://github.com/geotools/geotools/blob/master/modules/library/coverage/src/main/java/org/geotools/coverage/processing/operation/Resampler2D.java#L631
>
> Here's then where jai uses the background values if the value doesn't
> exceed sourceThreshold:
>
> https://github.com/mauricio/jai-core/blob/master/src/share/classes/com/sun/media/jai/opimage/MosaicOpImage.java#L2059
>
> In our case, we have valid values less than 1.0 and the background value
> is NaN so we are effectively arbitrarily masking some of our values. I get
> how we could just determine if the resample operation is going to result in
> a Mosaic operation and then make sure the parameters are set to something
> valid. But this is just one case and its nice that the resample operation
> is generalized for us so we don't have to determine the underlying
> operation.
>
> I'd think that the Resampler2D code could at least try to infer the
> threshold as the minimum values from the GridSampleDimension[] of the
> coverage. Does that make sense?
>
> I actually don't entirely get when this sourceThreshold is useful - as
> long as the background and no data values for the source and destination
> are the same it seems unnecessary. So perhaps in the spirit of eventually
> using jai-ext this should be something that defaults as just not being used?
>
> Please let me know what path I should try to go down. Thanks,
> Rich
>
>
> ------------------------------------------------------------------------------
> Dive into the World of Parallel Programming. The Go Parallel Website,
> sponsored by Intel and developed in partnership with Slashdot Media, is
> your
> hub for all things parallel software development, from weekly thought
> leadership blogs to news, videos, case studies, tutorials and more. Take a
> look and join the conversation now. http://goparallel.sourceforge.net/
> _______________________________________________
> GeoTools-Devel mailing list
> GeoTools-Devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/geotools-devel
>
>
--
==
GeoServer Professional Services from the experts! Visit
http://goo.gl/NWWaa2 for more information.
==
Ing. Nicola Lagomarsini
Junior Software Engineer
GeoSolutions S.A.S.
Via Poggio alle Viti 1187
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.
------------------------------------------------------------------------------
Dive into the World of Parallel Programming. The Go Parallel Website,
sponsored by Intel and developed in partnership with Slashdot Media, is your
hub for all things parallel software development, from weekly thought
leadership blogs to news, videos, case studies, tutorials and more. Take a
look and join the conversation now. http://goparallel.sourceforge.net/
_______________________________________________
GeoTools-Devel mailing list
GeoTools-Devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/geotools-devel
