[gdal-dev] RFC 58: Removing Dataset Nodata Value

[Even Rouault]

Le mardi 19 mai 2015 16:16:05, Ivan Lucena a écrit :
> > From: even.rouault at spatialys.com
> > To: gdal-dev at lists.osgeo.org
> > Subject: Re: [gdal-dev] RFC 58: Removing Dataset Nodata Value
> > Date: Tue, 19 May 2015 16:10:38 +0200
> > CC: lucena_ivan at hotmail.com; jukka.rahkonen at maanmittauslaitos.fi
> > 
> > Le mardi 19 mai 2015 16:06:59, Ivan Lucena a écrit :
> > > Jukka/Even,
> > > 
> > > Yes, you guy are right. The  "-a_nodata none" will help but I still
> > > need to implement a value range check on my CreateCopy anyway. So
> > > users don't need to run gdal_translate again after they find the
> > > problem or use "-a_nodata none" all the time (in a script for example)
> > > and miss the good ones.
> > 
> > I'm wondering if it might not make more sense to modify the input
> > driver(s) to not report out-of-range nodata values ? I fail to see a
> > reason to report an out-of-range nodata value.
> 
> That makes sense but we would need to go though all drivers and basically
> copy&paste a value range code.
> 
> Could the GDAL *Core* GetNoDataValue do that instead?

Not really since GetNoDataValue() is a virtual method implemented in drivers 
that overload it.

We could however have a core internal helper method, let's say 
GDALRasterBand::IsValueInRange(double) ( or perhaps a more general purpose 
function in gcore/gdal_misc.cpp GDALDataTypeIsValueInRange(GDALDataType,  
double) ) that would do the check and would be called by drivers that need it.

> 
> > > Thanks.
> > > 
> > > > To: gdal-dev at lists.osgeo.org
> > > > From: jukka.rahkonen at maanmittauslaitos.fi
> > > > Date: Tue, 19 May 2015 13:43:38 +0000
> > > > Subject: Re: [gdal-dev] RFC 58: Removing Dataset Nodata Value
> > > > 
> > > > Ivan Lucena <lucena_ivan <at> hotmail.com> writes:
> > > > > Would that be feasible to accept the option "-a_nodata NO" on GDAL
> > > > > command
> > > > 
> > > > lines, to indicate that NoData should not pass from the input to the
> > > > output dataset?
> > > > 
> > > > Would it be something different than "-a_nodata none"?
> > > > 
> > > > -a_nodata value:
> > > >     Assign a specified nodata value to output bands. Starting with
> > > >     GDAL
> > > > 
> > > > 1.8.0, can be set to none to avoid setting a nodata value to the
> > > > output file if one exists for the source file. Note that, if the
> > > > input dataset has a nodata value, this does not cause pixel values
> > > > that are equal to that nodata value to be changed to the value
> > > > specified with this option.
> > > > 
> > > > -Jukka Rahkonen-
> > > > 
> > > > _______________________________________________
> > > > gdal-dev mailing list
> > > > gdal-dev at lists.osgeo.org
> > > > http://lists.osgeo.org/mailman/listinfo/gdal-dev

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