mapserv and ogr2ogr reprojection (Google Earth)

[Frank Warmerdam]

Eijnden, Bart van den (AGI) wrote:
> Hi list,
> 
> first of all, maybe this would be better addressed at the gdal-dev list as
> well.
> 
> Using Jan Hartman's PROJ.4 parameters for EPSG:28992
> (http://postgis.refractions.net/pipermail/postgis-users/2005-November/009894.html),
> we successfully got Dutch national grid data to match the aerial
> photography of Google Earth.
> 
> We used Mapserver WFS and ogr2ogr (GML input, KML output) to transform the
> data.
> 
> If we transform using ogr2ogr and provide -s_srs with the exact same PROJ.4
> string and t_srs of EPSG:4326, the overlay is not correct.
> 
> Any ideas what could be causing this? All testing was done using FWTools
> 1.0.5 on Windows XP.

Bart,

It is not immediately clear to me why this would not work properly.  I
did check the PROJ.4 coordinate system in question, and it appears to
go through OGR's internal SRS conversions without any damage.

If you could submit a bug report against OGR with all the details I will
dig into it.  In particular what I would like to see is a point transformed
through ogr2ogr producing a different output value than the same point
transformed using cs2cs.   I gather your central premise is that with
cs2cs you got the expected results, but you didn't see the same results with
ogr2ogr, right?

> Another question:
> 
> -how hard would it be to have the same OUTPUTFORMAT mechanism for vector
> (Mapserver WFS/OGR), so that output formats of OGR could be outputted by
> Mapserver WFS?

It would be a fairly substantial effort I think.  I gather we would need
something roughly analygous to mapgml.c that can write via an OGR driver,
and then various machinery connecting up format selection in the wfs output.
Perhaps a 2-3 week development effort.

I think we would also need a mechanism to identify files to "bundle up"
in a zip or something similar for multi-file formats such as shape, or
mapinfo.

But I can see that this would be an interesting capability.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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