[Gdal-dev] OGR transforms

[Frank Warmerdam]

Curt, WE7U wrote:
> Opening datasource
> /usr/local/share/xastir/maps/World/USA/WA/SDTS/24k/darrington/hypsography/HP01CATD.DDF
> Features Processed: 1
> ERROR 1: geocentric transformation missing z or ellps
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 1
> ERROR 1: geocentric transformation missing z or ellps
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 1
> ERROR 1: geocentric transformation missing z or ellps
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 4
> ERROR 1: failed to load NAD27-83 correction file
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 49
> ERROR 1: failed to load NAD27-83 correction file
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 433
> ERROR 1: failed to load NAD27-83 correction file
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 782
> ERROR 1: failed to load NAD27-83 correction file
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 1082
> ERROR 1: failed to load NAD27-83 correction file
> Couldn't convert points from WGS84 to map's spatial reference
> Features Processed: 434
> 
> Am using CVS GDAL/OGR from some months back.  Was there something I
> forgot to load?  I'm assuming that the "geocentric transformation
> missing" messages are due to those layers not having any sort of
> spatial reference.  I'll look into that further (as in: Don't try to
> convert my view edges to the map coordinate system if there isn't
> one for that layer!).
> 
> The ones that worry me more are the "NAD27-83 correction file"
> messages.

Curt,

I'm not sure exactly what is happening. All the errors are coming from
PROJ.4.  The geocentric one could be result of an improperly specified
ellipsoid.  What are your source and destination coordinate systems
(in WKT)?  The NAD27-83 correction issue presumably means you are trying
to convert from WGS84 (essentially the same as NAD83 for my purposes) to
NAD27.  If you want to do this you need to install the grid shift files
as part of the PROJ.4 installation process.  This can be accomplished
by overlaying the grid shift files on the PROJ distribution (they go
in the proj/nad directory) before configuring PROJ.4.

   ftp://ftp.remotesensing.org/pub/proj/proj-nad27-1.1.tar.gz

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent