[fdo-internals] Coordinate system support for FDO

Orest Halustchak orest.halustchak at autodesk.com
Tue Dec 18 09:04:59 EST 2007


Hi,

I'm forwarding this thread that started on the MapGuide discussion lists. The question is where should coordinate system transformation support reside, as functionality within FDO providers or as client-tier / viewer-tier component?

There are some notes started in the FDO wiki under FDO Futures Discussion -> FDO Client Utilities (http://trac.osgeo.org/fdo/wiki/FdoClientUtilities).

For anyone interested, please let us know your thoughts on this.

Thanks,
Orest.

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Maksim Sestic
Sent: Tuesday, December 18, 2007 6:11 AM
To: mapguide-internals at lists.osgeo.org
Subject: RE: RE: [mapguide-internals] [mapguide-users] Adding a CoordinateSystem to MGE/MGOS


Hi Orest,

IMHO, FDO needs that CRS part to be truly independant of the viewer tier
(and some client-tier commercial products, BTW). CRS core somehow doesn't
fit on viewer tier, although it's heavily used there. I've been working with
SharpMap implementation where coordinate transformation engine is tightly
coupled with geometry factory. When applied to FDO, you may have a common
feature store CRS (if any) regularly "overriden" by simply passing new CRS
type to geometry factory as a parameter, which automatically performs
coordinate transformation on resulting geometries.

I guess we should continue this discussion on FDO Futures wiki :-)



Orest Halustchak wrote:
>
> Hi Maksim,
>
> The FDO Client Utilities section of FDO Futures is there for discussion
> and is not an established "plan". The points included in that page are
> ones that some folks have raised recently. We posted the ideas so that we
> could start a discussion and get some more feedback. So, if you have some
> ideas or feedback that you'd like to throw in there, please feel free to
> add your comments.
>
> Regarding CRS support in FDO, as Jason points out, FDO doesn't do
> coordinate transformation itself. FDO can return the CRS definition from
> the data source if it is known (returned as a WKT string). That definition
> is passed by MG to Proj4 or Mentor. MG relies on these libraries to
> recognize the CRS definition.
>
> Thanks,
> Orest.
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Maksim
> Sestic
> Sent: Monday, December 17, 2007 4:54 AM
> To: mapguide-internals at lists.osgeo.org
> Subject: RE: RE: [mapguide-internals] [mapguide-users] Adding a
> CoordinateSystem to MGE/MGOS
>
>
> Jason, is there some sort of "global" OSGeo roadmap on active projects and
> code being shared among them? Like - what project depends on other
> projects'
> deadlines, common cores (i.e. FDO in MG), etc. I guess there's a
> geospatial
> product manager somewhere at Autodesk who actively tracks this :-)
> Otherwise
> there will be lots of inner branching and wheel reinventing, but the
> purpose
> stays the same.
>
> Frankly, lack of CRS support in FDO is still mistery to me :-) MG should
> be
> able to detect and reuse any managed feature store's CRS, where applicable
> (if not explicitly overriden by MG at feature source level). This should
> also solve WMS/WFS troubles on WGS84 reprojection parameters and envelope
> definition.
>
> If I understood "FDO Futures" right, there's a plan to gradually switch
> general FDO architecture to client/server?
>
> Regards,
> Maksim Sestic
>
>
>
> JasonBirch wrote:
>>
>> FDO doesn't do coordinate transformation yet.  There has been some talk
>> about adding this at a "utility" layer (see the "Futures" section on the
>> FDO Trac wiki) but this discussion hasn't received much attention yet.  I
>> believe that this is because of time constraints on the part of
>> interested
>> parties, because there was a lot of interest in this at FOSS4G.
>>
>> Jason
>>
>> ________________________________
>>
>> From: Maksim Sestic
>> Subject: RE: RE: [mapguide-internals] [mapguide-users] Adding a
>> CoordinateSystem to MGE/MGOS
>>
>>
>>
>> Another thing - what about underlying FDO, shouldn't it have Mentor
>> libraries implemented in first place? I haven't seen any 3.3.0 RFC
>> related
>> to it. Will Mentor implementation affect existing FDO providers?
>>
>>
>>
>> _______________________________________________
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>> mapguide-internals at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
>>
>>
>
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