Vincent, > > I'd like to develop a ogr driver to create .map files used by WAsP > <http://en.wikipedia.org/wiki/WAsP> > > The .map files contains height contours and roughness zones, the former > are linestrings with an height attribute, the later are linestrings that > separate two adjacent polygons with a roughness parameter on the righ > and left sides. > > An algorithm to create roughness zones from polygons with a roughness > attribute would be useful: extract the polygon boundaries and output > linestrings with attributes on the left and right sides. > > What driver would you recommend as a starting point to get the > interface, the coding style and the error handling right ?
A write-only driver if I understand well ? There are not so many instances of such drivers. I can think to the PGDump driver. As far as coding style, there's http://trac.osgeo.org/gdal/wiki/rfc8_devguide with a few general guidelines. > > Is the algorithm to create roughness zones from polygons (i.e. extract > polygon boundaries and add left/right attributes) something that should > be integrated in the driver, somewhere else or not at all in gdal ? That's certainly the trickiest part of your task. There's no such algorithm in GDAL. I'm not very familiar with that but it sounds a bit like topological processing. Perhaps PostGis topology could be used to compute the edges from the polygons ? Reading the introduction of http://postgis.net/docs/Topology.html, I can see that you should have in- house competences on that ;-) There's an idea for GSOC 2014 (Geography network support : http://trac.osgeo.org/gdal/wiki/SummerOfCode ) that seems a bit connected with your problem and could potentially served as the base for such algorithm. But I'm not sure that GDAL alone could solve it. You likely need some intermediate storage to store and retrieve the edges from the polygon set (unless you have not that many polygons to deal with in which case in-memory processing could be OK). Even -- Geospatial professional services http://even.rouault.free.fr/services.html _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
