[Gdal-dev] Using OGR Python to analyse stream layers

[Sean Gillies]

Not to drag this thread further off course, but what we _really_ need
is a Python interface to GEOS using Boost.  I'm way too busy to lead
this right now, but could help.  The Boost docs make it seem like a
not-too difficult project.

cheers,
Sean

On Feb 9, 2004, at 11:24 AM, Chris G. Nicholas wrote:

>
>
> folks might want to look at the new GEOS functionality in PostGIS,  
> that includes buffering, intersect, union, etc.
>
> seems to work beautifully...
>
> Chris Nicholas
> GlobeXplorer
>
> -----Original Message-----
> From:	Frank Warmerdam [mailto:warmerdam at pobox.com]
> Sent:	Mon 2/9/2004 10:03 AM
> To:	gdal-dev at remotesensing.org
> Cc:	
> Subject:	Re: [Gdal-dev] Using OGR Python to analyse stream layers
> Christopher Fonnesbeck wrote:
>> Thanks for the advice! What if I had a polygon coverage with affected
>> polygons instead; could those then be intersected with a stream
>> coverage, or is that outside of OGR's realm?
>
> Chris,
>
> OGR does not support much in the way of geometry intersection  
> operations.
> What it does offer is a bounding box spatial filtering.  That is, a
> rectangular bounding box can be set as a spatial filter, and then when
> you iterate through the features, only those intersecting that bounding
> box will be returned.
>
> For the time being I have tried to leave complex geometry operations to
> packages like GEOS though I do hope to incorporate their use into
> OGR at some point.
>
>> Is there documentation/examples of how OGR handles line features like
>> stream networks?
>
> There is substantial documentation on the C/C++ interface to OGR ...  
> less
> on the python interface. I can provide a small sample script that would
> read lines from a data source, and print out the set of vertices if you
> need it.
>
>> I presently use MySQL for all my GIS databasing, and version 4 now
>> supports storage of spatial features. Is there a mysql driver for OGR?
>
> I am not all that familar with the new spatial features in MySQL.  I am
> not convinced it includes rigerous geometry operations though.  There  
> is
> not any direct support for the new MySQL geometry types in OGR though  
> I hope
> to incorporate that at some point, possibly layered on the existing  
> ODBC
> driver in OGR which I have been using for MySQL based applications so  
> far.
>
> I'm sorry I don't have a more cut-and-dried solution for you.
>
> 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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--
Sean Gillies
sgillies at frii dot com
http://users.frii.com/sgillies