[Proj] PROJ 4.6.0 beta1 Release

[Brent Fraser]

Frank,

  Sounds like a good idea, but will the API return a code,
or through some other mechanism, indicate that a datum
transformation has not occured?  The application could then
alert the user...

Brent Fraser
GeoAnalytic Inc.
Calgary, Alberta
----- Original Message ----- 
From: "Frank Warmerdam" <warmerdam at pobox.com>
To: "PROJ.4 and general Projections Discussions"
<proj at lists.maptools.org>
Sent: Thursday, November 29, 2007 2:44 PM
Subject: [Proj] PROJ 4.6.0 beta1 Release


> Folks,
>
> There have been many complaints from folks about
pj_datum_transform()
> doing "ellipse to ellipse" datum shifts when no datum
shift information
> is available.  I have come to the, belated, conclusion
that the idea will
> ill conceived on my part, and I have reversed my approach.
>
> Now, if pj_datum_transform() (called pj_transform()) is
called, and
> either of the coordinate system lacks datum information it
will apply no
> datum shift at all.  The lat/long coordinates will be
taken from one
> and applied on the other with alteration.
>
> Datum shift information can be specified two ways, a
+towgs84 parameter,
> or a +nadgrids parameter.  The +datum parameter is
basically for named
> aliases that expand to +ellps and either +nadgrids or
+towgs84 parameters.
>
> This is a major behavior change, and I'd appreciate folks
giving some feedback
> on the change.  I have prepared a first beta release with
this change,
> designated 4.6.0 beta1.
>
> This release also includes an upgrade to EPSG 6.14 and a
few other relatively
> minor bug fixes.
>
>    http://download.osgeo.org/proj/proj-4.6.0b1.tar.gz
>    http://download.osgeo.org/proj/proj-4.6.0b1.zip
>
> Best regards,
> -- 
> ---------------------------------------+------------------
--------------------
> 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
>
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