[Gdal-dev] GEOCCS - Geocentric CS in OGR?

[Frank Warmerdam]

Craig Miller wrote:
> I'm working throught the WKT spec in the SF COM document and it lists three
> categories of SRSs:
> 
> Geographic - GOEGCS
> Projected  - PROJCS
> Geocentric - GEOCCS
> 
>>From what I can tell OGR has three categories too:
> 
> Geographic => IsGeographic()  - GEOGCS
> Projected  => IsProjected()   - PROJCS
> Local      => IsLocal()       - LOCALCS  or LOCAL_CS (according to OGR docs)
> 
> With this in mind...
> 
> - How are geocentric coordinate systems represented in OGR?

Craig,

I don't believe geocentric coordinate systems are currently
supported by the OGRSpatialReference in GDAL/OGR.  This is a
deficency.  There is geocentric support in PROJ.4 by the way.

> - If GEOCCS is supported, why isn't there a IsGeocentric() method?
> - Is OGR the only product that supports the LOCALCS object?

The LOCALCS concept was introduced in the CT (Coordinate Transformations)
specification which extended the WKT syntax.  I'm not sure how widely
supported this is, but there are other systems.

> - Is it LOCALCS or LOCAL_CS?

It would appear it is really LOCAL_CS when expressed in WKT.  I see
that some of the OGR methods are like "SetLocalCS" but I think of that
as part of the transformation to StudlyCaps.

Best regards,
-- 
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