[gdal-dev] Internal Metadata Management

[Ricardo Filipe Soares Garcia da]

Hi Frank

Check out this link [1]. It is the online reference on a Utah
University course called 'Geoprocessing with Python using Open Source
GIS'. It uses GDAL/OGR and is great as a starting point. It has helped
me plenty ;)

[1] - http://www.gis.usu.edu/~chrisg/python/

On Tue, Dec 14, 2010 at 8:40 AM, Ari Jolma <ari.jolma at gmail.com> wrote:
> Frank,
>
> A FeatureDefn is typically shared by all features in a layer and you need
> one to create a feature object. Feature class has SetField and GetField
> methods for storing and retrieving the attributes of a feature.
>
> I hope this helps,
>
> Ari
>
> On 12/14/2010 09:33 AM, Frank Broniewski wrote:
>>
>> Hello,
>>
>> I have a question concerning OGR's metadata or attribute management when
>> converting between geodata vector formats. My question is maybe only loosely
>> related to OGR and aims at the internal management of attribute data.
>>
>> From what I have read and understood from the documentation, OGR uses the
>> OGC Simple Feature Specifiaction to transform data from one format to
>> another. While reading the OGC specs I could not find a notion on how one
>> should deal with attribute metadata, the whole spec seems to be about vector
>> geometries only.
>>
>> Why I ask this: I am a Python user using the ogr python bindings and now
>> the need arose that I need to write a flexible geo format exchange software.
>> I chose OGR as a base for doing the conversion. My data often comes from
>> databases with non standard data and geoemtry formats. So I want to align
>> with OGR's internal used Simple Feature Data format, but I don't know
>> how/where I should put the attributes / metadata. I see that the Feature is
>> the part I have to look at because it has the geometry and the FeatureDfn.
>> Unfortunately this is the part I don't understand :-)
>> I need to create a FeatureDfn for my Feature which is basically the column
>> names and data types? Where do I put my attribute values then? I looked at
>> the OGRFeatureDefn Class Reference, but my understanding of OGR is too low
>> to understand how this relates to the OGRFeature.
>>
>> So basically I am looking for a starter tip that pushes me into the right
>> direction. Is there some python tutorial somewhere which I missed or
>> somebody has a code snippet for me?
>>
>> Or would it be easier to use internally a format like geojson and use this
>> as a starter for converting to other formats? Can OGR always transfer the
>> attributes of my geospatial data to other formats?
>>
>> I am sorry that my question is somewhat unclear, but I have some
>> difficulties to find the right form for my question. But I hope that I could
>> state my problem in an understandable way :-)
>>
>> Many thanks for any tipps
>>
>> Frank
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>
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-- 
___________________________ ___ __
Ricardo Garcia Silva