[mapserver-users] TIFF/GeoTIFF and World Files

[kenboss]

We use geotiffs in several mapserver apps here.  We don't use .tfw files, and 
since all of our images and vector datasets are in the same projection system, 
we don't need PROJECTION sections in the mapfiles, either.

--Ken

> Chris Stuber wrote:
> > 
> > MapServer Folks,
> > 
> > Back on the topic of raster images...   In the past, I have manually created 
a
> > world file to go with my raster images.  I ran across a dataset (actually it 
is
> > software) that generates GeoTIFF output.  The GeoTIFF file contains
> > GeoKeyDirectories with the following keys/values defined for each image:
> > 
> >      KeyDirVersion: 1, KeyMaj/MinRev: 1/2
> >      NumKeyDirKeys: 12
> >      GTModelTypeGeoKey: 2 (ModelTypeGeographic)
> >      GTRasterTypeGeoKey: 1 (RasterPixelIsArea)
> >      GeographicTypeGeoKey: (value always NAD83 or WGS_84 [virtually the same
> > datum])
> >      GeogPrimeMeridianGeoKey: 8901 (PM_Greenwich)
> >      GeogAngularUnitsGeoKey: 9102 (Degrees)
> >      ProjectedCSTypeGeoKey: 32767 (UserDefinedVal)
> >      ProjectionGeoKey: 32767 (UserDefinedVal)
> >      ProjCoordTransGeoKey: 8 (currently always CT_LambertConfConic [could
> > change])
> >      ProjStdParallelGeoKey: (value = Standard Parallel closest to equator)
> >      ProjStdParallel2GeoKey: (value = Standard Parallel furtherest from 
equator)
> >      ProjNatOriginLatGeoKey: (value = Mid Latitude)
> >      ProjCenterLongGeoKey: (value = Central Meridian)
> > 
> > Now, my question is... to what degree does mapserver support GeoTIFF?  Will
> > mapserver
> > read these GeoTIFF attributes?  Do I still need to create a world file to 
match
> > the
> > image?    By default, no ".tfw" is generated from this software.....   If a
> > world file
> > *is* required, can it computed from the GeoTIFF Header information??     
There
> > will be
> > quite a few images, and I can't image having to manually create world files 
for
> > each.
> 
> Chris, 
> 
> My understanding is that MapServer's existing (pre 3.5) TIFF support will
> read the georeferencing coefficients from the .tif file if available, in which
> case no .tfw is required.  However, it does not read the coordinate system
> definition, so you might need to define it using a PROJECTION section in your
> map file.  If, for some reason, you want a .tfw file anyways and aren't sure
> how to create it by hand, the listgeo utility distributed with libgeotiff 
> (http://www.remotesensing.org/geotiff/geotiff.html) includes the ability to
> create a .tfw file from a GeoTIFF file. 
> 
> In the CVS code my new GDAL code will even read the projection definition, 
> removing the need for a user supplied conversion into PROJ.4 format. 
> 
> Best regards,
> 
> ---------------------------------------+--------------------------------------
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