[gdal-dev] Change to SetMercator and SetMercator2SP creates WKT without Latitude of Origin parameter

[Frank Warmerdam]

Chris Eustace wrote:
> This question is probably directed to Frank.
> 
> Our autotests here at work have shown there are differences between the 
> CRS WKT strings generated from GDAL v1.4.4 to GDAL v1.5.1.
> 
> I've scanned around a bit and noticed that ogrspatialreference.cpp has 
> altered between these versions.
> 
> I did a bit more hunting and found that the GDAL changeset number 
> concerned is 12207. The subject relates to moving sfc/oledb stuff for 
> the move to spike.
> 
> My question is, whether the changes to the SetMercator calls are 
> intended changes to ogrspatialreference.cpp or not? What we are seeing 
> here is that if "dfCenterLat" is 0.0, that Latitude Of Origin parameter 
> is no longer present in the resultant WKT.

Chris,

Hmm, that is funky.  It clearly has nothing to do with the migration of
oledb stuff to spike.  It must have got caught up in a big commit by
accident.  I'm not sure what the rationale for it was.

Is this ommission causing problems for something?  Generally GDAL itself
will assume zero values for parameters like this if they are omitted.

I assume at the time I was looking into some issue with software packages
not expecting this parameter for Mercator (perhaps ArcGIS?) and was
experimenting with only including it if it was non-default, but I don't
recall in any detail.

I would suggest you file a ticket on the issue, and include any notes
on why it is causing you problems.  I can at least check ArcGIS PE WKT
and see if it includes this parameter.

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    | President OSGeo, http://osgeo.org