[fdo-internals] RFC 11 has been posted

[Orest Halustchak]

Hi Frank,

Adding projection support to FDO hasn't been on the radar screen (at
least any that I've seen). Focus so far has been on keeping FDO as the
basic data access layer that does not try to modify the data going in or
coming out. Projection operation or other data modification (e.g.
converting arcs to polylines) is being done at a higher level.

Do we want to change this? If we want to discuss this, then this is the
right forum in which to do that, but I'd like to decouple it from the
RFC 11 discussion. I'd like to come up with an approach to add area and
length support if possible within the current framework of what fdo does
and have the projection discussion separately.

Thanks,
Orest.

-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Frank
Warmerdam (External)
Sent: Friday, September 07, 2007 3:56 PM
To: FDO Internals Mail List
Subject: Re: [fdo-internals] RFC 11 has been posted

Orest Halustchak wrote:
> Hi Frank,
> 
> The FDO api does not include any coordinate system transformation
> abilities. The only coordinate system information that is included is
> the ability to specify a coordinate system for a geometry property
(via
> spatial context) and to get that information back when describing that
> property. There are no commands to specify input or output coordinate
> systems for the purposes of projecting coordinates.
> 
> All projection work so far has been done by client applications, e.g.
> MapGuide projects coordinates into the map coordinate system after
> retrieving geometry from the provider. This does ensure that a
> consistent projection library is used regardless of which provider the
> data is coming from.

Orest,

OK, I can understand that, and it might be foolish to start introducing
reprojection without some consideration.  But is this our long term
plan?

It seems like it puts an unnecessary load on applications and the
disconnectedness of FDO's spatial reference descriptions from a
coordinate
system transformation library may impede FDO adoption.

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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