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I posted this a few days ago to the ArcGIS Discussion Forum but have had no response so thought I would try here as well.

I'm new to Web Coverage Services (WCS) but have found it easy to add one using ArcGIS for Desktop 10.1 and this service URL:

http://nsidc.org/cgi-bin/atlas_south?service=WCS&request=GetCapabilities&version=1.1.1

I add the service by Liu et al. and get a nice display.

However, when I use Identify to look at the values for any cell on the grid/coverage all Stretched Values and Pixel Values are in the range 0-255. I would expect to see 0-255 used for the Stretched Values but thought the Pixel Value would be holding raw data with values well in excess of 255.

When I export data from the WCS to a file geodatabase raster the values there are 0-255 too.

Is it possible to access the raw values held in a WCS?

(Hopefully I am just misunderstanding how to get my desired result)

UPDATE

NSIDC have said that their server is configured to provide data in GeoTIFF format. Their docs make it appear that GeoTIFFInt16 and GeoTIFFFloat32 are both options but they suspect that the GetCoverage request generated by ArcGIS for Desktop 10.1 is using a format that maps the data into an 8-bit format instead.

As a supplementary question, does anyone know if there is an option within ArcGIS for Desktop to select the GeoTIFF format used by GetCoverage or a way to trap the GetCoverage URL that it is passing to the WCS server?

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Do you know who is serving this WCS? If so, I would ask them if the raster has a colormap associated with it. If it does, the GIS Server might be serving the colormap values instead of the actual raster values. –  user15920 Mar 8 '13 at 0:30
    
Thanks - I'm checking with nsidc@nsidc.org now. –  PolyGeo Mar 8 '13 at 1:34
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up vote 0 down vote accepted

There is an existing ArcGIS Idea called Identify tool should return the raw grid data value as well as the smoothed value which I will add my vote to.

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