No problem moving to the users list - I figured this would be more
appropriate there but I wasn't able to find the address at the time I sent
this email (looking again it's pretty plain on the 'Get Involved' page on
geotools.org ; clearly my mistake.)
The ZonalStats operator looks like just what I was looking for; thanks.
(Side note to others who might come across this: the parameter listed as
"exclude" in the javadocs is actually named "noDataRanges".)
--
David Winslow
OpenGeo - http://opengeo.org/
On Tue, Apr 12, 2011 at 12:51 AM, Michael Bedward <[email protected]
> wrote:
> Hi David,
>
> I'm moving your question to the user list - I hope that's alright.
>
> The JAI Extrema operation doesn't have any parameters for excluding
> one or more values. You might like to look at the
> unsupported/jai-tools module. It wraps the JAI-tools ZonalStats image
> operator for use in GeoTools. This operator lets you define values or
> ranges of values to treat as NODATA:
>
> Here are the javadocs for the operator:
>
>
> http://jai-tools.org/docs/jai-tools/stable/apidocs/jaitools/media/jai/zonalstats/ZonalStatsDescriptor.html
>
> Michael
>
>
> On 8 April 2011 02:04, David Winslow <[email protected]> wrote:
> > Hi all,
> > I'm trying to inspect some geotiffs so I can generate color
> > ramps appropriate to the value range present. but when i retrieve the
> > extrema for a coverage band the NODATA value is not ignored - so my ramp
> > ends up being broader than i'd like. I was hoping to find something like
> > the existing Extrema operation, but with a parameter containing a list of
> > values to ignore (or a list of such lists per band.) I don't see such a
> > thing in either GeoTools or JAI (but I am a JAI newbie so I might have
> > missed something).
> > In case it's not clear what I'm looking for, find attached a very basic
> > implementation of what I'm thinking of (see findExtrema at the end of the
> > file). I'd be happy to clean it up for inclusion in GeoTools if this is
> > something that seems desirable, though I might need a bit of help fitting
> > into the existing Operation system - I didn't see anything in the docs
> on
> > adding new ones to the library.
> > I also noticed that while GridSampleDimension has a method
> > getNoDataValues(), it actually returns null for GeoTIFFs, even ones that
> do
> > populate the GC_NODATA property. Is this behavior intentional?
> > --
> > David Winslow
> > OpenGeo - http://opengeo.org/
> >
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> > [email protected]
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> >
> >
>
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