[Geotiff] CT_HotineObliqueMercatorAzimuthCenter added .. new CT_ policy

[Frank Warmerdam]

Folks,

At the point when GeoTIFF was created EPSG (apparently) did not have
an enumeration for coordinate transformation methods (like Transverse
Mercator).  So the GeoTIFF spec embedded it's own - the CT_*
constants in geo_ctrans.inc.

Shortly after that EPSG added the coordinate_operation_method
table but the split had already occured.  Since EPSG has added many
projection methods not included in GeoTIFF.   It looks like I, by fiat,
added CT_CylindricalEqualArea and perhaps CT_TransvMercator_SouthOrientated
with consecutive codes.  However, this did not do much to catch things
up with EPSG.

I have recently done a bunch of work in GDAL to differentiate
EPSG's hotine oblique mercator methods, marking 9815
as distinct with a name of Hotine_Oblique_Mercator_Azimuth_Center.
I was going to add it to GeoTIFF too but I really don't want to have
distinct codes between EPSG and GeoTIFF.  So I am suggesting
(and implementing) a move to using the EPSG transform codes for
new projection methods.

Are there there any questions or concerns about this?

eg.

in geo_ctrans.inc:

/* Added May 2012 - from now on we use the EPSG */
ValuePair(CT_HotineObliqueMercatorAzimuthCenter, 9815)


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 Software Developer