[gdal-dev] sounding point handling by OGR library

Frank Warmerdam warmerdam at pobox.com
Tue Sep 29 12:20:49 EDT 2009

Yilmaz Arslanoglu wrote:
> Hi;
> I had some questions regarding the additional feature of sounding
> point handling by the OGR library.
> I know that we need to turn on the options SPLIT_MULTIPOINT and
> ADD_SOUNDG_DEPTH options on.
> 1) Is there a way to turn them individually on without affecting the
> other suboptions in OGR_S57_OPTIONS ?
>     Because if we do it by the following statement:
>    CPLSetConfigOption("OGR_S57_OPTIONS",
>    Then there is a possibility to overwrite the other suboptions


You are correct, calling CPLSetConfigOption() will clear the previous
setting, so if you want things amalgamated you need to do it
yourself in code in some fashion.

> 2) With turning ADD_SOUNDG_DEPTH option on, the points become three
> dimensional, where the Z
>     member variable contains the retrieved depth value I guess. Here,
> my question is, does this depth
>     retrieval process take care of any unit conversions (meters,
> fathoms, feet, etc.) ?

I do not believe it is doing any unit conversion.  You will
get a Z coordinate in the depth units that it appears in
the depth attribute.

In general OGR and OGRSpatialReference do not attempt to
address the units of Z values even though there is an OGC
coverage of compound (ie. 2D + elevation) coordinate systems.

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    | Geospatial Programmer for Rent

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