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Linear_Foot_Modified_American = 9004

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	Linear_Foot_Modified_American = 9004 by Mathieu.St-Pierre :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Some parts of this message have been removed. Learn more about Nabble's security policy. Hi all, I got a GeoTIFF image whose key GeogLinearUnitsGeoKey has the value 9004. It seems that this unit code is specified nowhere, not even in libgeotiff or the EPSG database. Why is it in the GeoTIFF specification? Where does it come from? Thanks _______________________________________________ Geotiff mailing list Geotiff@... http://lists.maptools.org/mailman/listinfo/geotiff
	Re: Linear_Foot_Modified_American = 9004 by Christian Zietz :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Mathieu.St-Pierre@... schrieb: > I got a GeoTIFF image whose key GeogLinearUnitsGeoKey has the value 9004. > It seems that this unit code is specified nowhere, not even in > libgeotiff or the EPSG database. > Why is it in the GeoTIFF specification? Where does it come from? Since the libgeotiff includes and the specification are based on a very old version of the EPSG database (v. 2.1), my guess is that the code 9004 was defined there and that it was removed in a later version of the EPSG database. Unfortunately I can't find such an old release of the EPSG DB to confirm this. Christian -- Christian Zietz - CHZ-Soft - czietz@... WWW: http://www.chzsoft.com.ar/ PGP/GnuPG-Key-ID: 0x6DA025CA _______________________________________________ Geotiff mailing list Geotiff@... http://lists.maptools.org/mailman/listinfo/geotiff
	RE: Linear_Foot_Modified_American = 9004 by Max Martinez :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message All previous changes are available in whatever version of the EPSG database you are using. Examining the change report from the 6.14 version, you find that this unit was eliminated in July of 1998: #933 1998.220 State Plane units Report date: 21-Jul-98 Changed units for Clarke 1866 Michigan ellipsoid and all six NAD27 Comment: Michigan State Plane zones from Modified American foot to US Survey Foot. Deleted Modified American foot. Action: Codes affected: 7009 9004 12101-3 12111-3 26801-3 26811-3 Reporter: Melita Kennedy; ESRI Tables affected: Ellipsoid HorizCS Trf_nonpoly UOM_length -----Original Message----- From: geotiff-bounces@... [mailto:geotiff-bounces@...] On Behalf Of Christian Zietz Sent: Thursday, April 10, 2008 4:35 AM To: geotiff@... Subject: Re: [Geotiff] Linear_Foot_Modified_American = 9004 Mathieu.St-Pierre@... schrieb: > I got a GeoTIFF image whose key GeogLinearUnitsGeoKey has the value 9004. > It seems that this unit code is specified nowhere, not even in > libgeotiff or the EPSG database. > Why is it in the GeoTIFF specification? Where does it come from? Since the libgeotiff includes and the specification are based on a very old version of the EPSG database (v. 2.1), my guess is that the code 9004 was defined there and that it was removed in a later version of the EPSG database. Unfortunately I can't find such an old release of the EPSG DB to confirm this. Christian -- Christian Zietz - CHZ-Soft - czietz@... WWW: http://www.chzsoft.com.ar/ PGP/GnuPG-Key-ID: 0x6DA025CA _______________________________________________ Geotiff mailing list Geotiff@... http://lists.maptools.org/mailman/listinfo/geotiff _______________________________________________ Geotiff mailing list Geotiff@... http://lists.maptools.org/mailman/listinfo/geotiff
	Linear_Foot_Modified_American = 9004 by Mathieu.St-Pierre :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Some parts of this message have been removed. Learn more about Nabble's security policy. Thanks Max, Christian and John for your answer. I’ll use the EPSG code specified by ProjectedCSTypeGeoKey (whose value is PCS_NAD27_California_VI 26746) and simply ignore the GeogLinearUnitsGeoKey key. Though I think that for back compatibility purpose, I would still like to have the definition of the linear foot modified American unit. I searched for the older EPSG databases but the oldest version I can find on the EPSG website is version 5.3 (2002). So, I wonder that, if the definition of the unit 9004 is lost, how can a GeoTIFF file whose geographic coordinate system is user defined (GeogLinearUnitsGeoKey == 9004) be reprojected correctly? Thanks, Mathieu _______________________________________________ Geotiff mailing list Geotiff@... http://lists.maptools.org/mailman/listinfo/geotiff

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