[gdal-dev] sounding point handling by OGR library

[Yilmaz Arslanoglu]

Thank you very much Frank for the quick and clear answers.

Best wishes,
Yilmaz

On Tue, Sep 29, 2009 at 6:20 PM, Frank Warmerdam <warmerdam at pobox.com> wrote:
> 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",
>> "SPLIT_MULTIPOINT=ON,ADD_SOUNDG_DEPTH=ON");
>>
>>   Then there is a possibility to overwrite the other suboptions
>> UPDATES, RETURN_PRIMITIVES,
>>    PRESERVE_EMPTY_NUMBERS, LNAM_REFS, and RETURN_LINKAGES.
>
> Yilmaz,
>
> 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
>
>