[Gdal-dev] Problems retrieving z-values

[tjansson]

Thanks! That seems plausible.

Does anyone know of a way/have an example of how to extract the
depth-attribute from the different features (e.g. depth contour)?

--Tommy


Frank Warmerdam-2 wrote:
> 
> On 9/26/07, tjansson <tommy.jansson at kongsberg.com> wrote:
>>
>> I am writing a library which reads S-57 files (of type *.000) and loads
>> selected geometies into a custom class structure. The files are read and
>> content handled using the OGR Simple Features Library for C++.
>>
>> As far as I have understood the various geometries are divided into two
>> categories; 2D geometry types with XY-data, and 2.5D geometry XYZ-data.
>>
>> I am interested in geometries of type 2.5D (i.e with XYZ-data). In my
>> code
>> there is a function which parses geometry objects using a switch that
>> check
>> the geometry type (and handles it accordingly). I have read several maps
>> with success (e.g. downloaded from NOAA), except that the Z-value is
>> always
>> set to 0 (zero). I've also noticed - when debugging - that the switch
>> never
>> hits on geometry type "wkbPoint25D" (or any other 2.5D type), which might
>> explain the Z-value.
>>
>> Is the code i have written doing something wrong, because I never get a
>> hit
>> on any 2.5D types, or are the maps I have downloaded the cause (because
>> they
>> don't contain any 2.5D types)?
> 
> Tommy,
> 
> I think SOUNDG features the the main feature type in S-57
> that actually returns 3D geometries, and they are normally
> of type wkbMultiPoint25D.
> 
> I *think* (memory grows foggy) that most other geometries
> you would think might be 2.5D - like depth polygons - just
> keep the depth as an attribute.
> 
> 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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> 

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