[Gdal-dev] geotiff nodata tag

[Ethan Alpert]

If anyone figures out how to get ArcMap to recognize it automatically
please post. I always have to select properties for the image layer and
under the Symbology tab select Display Background value (R,G,B) as no
color.

-e
-----Original Message-----
From: gdal-dev-bounces at lists.maptools.org
[mailto:gdal-dev-bounces at lists.maptools.org] On Behalf Of Frank
Warmerdam
Sent: Friday, October 07, 2005 1:17 PM
To: Matt Wilkie
Cc: gdal-dev at lists.maptools.org
Subject: Re: [Gdal-dev] geotiff nodata tag


On 10/7/05, Matt Wilkie <matt.wilkie at gov.yk.ca> wrote:
> Hi Folks,
>
> Frustratingly ESRI's ArcMap & Catalog  ignore the nodata value in 
> geotiffs created by gdal (for 8bit greyscale at least, I don't know 
> about RGBa). Is the nodata tag a specific gdal thing or is it part of 
> the official GeoTIFF spec?

Matt,

It is specifically a GDAL extension to the GeoTIFF format.  I think the
only way ArcMap would recognise the nodata value would be if an
appopriately constructed Imagine .aux file was associated with it.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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