Folks,
I have done a bit of work around OGR recently to make it easier to manage
schemas for layers as VRT files. For a project I wanted to be able to
have a VRT file which would define a set of layers with geometry types,
coordinate systems, fields and related information that I could use
with ogr2ogr or similar utilities to create all the layers.
To that end I have:
o Extended the VRT driver to support <Field> definitions giving all
the details of an attribute field on a layer (type, width, name, precision
and the source field it comes from in the source layer).
o Written an ogr2vrt.py script that will create a VRT corresponding to a
source datasource. This is the ogr equivelent to what we could do with
gdal_translate -of VRT in.tif out.vrt but for feature datasources. The
script currently lives in gdal/swig/python/samples but I may promote it
to the scripts directory implying it is supported if it is deemed to be
useful.
o Modified the VRT driver so that if the datasource name is @dummy@ it will
not go looking for an external file - it just creates a dummy memory
datasource and layer. This effectively turns the .vrt into a schema
definition since there will be no effort to go looking for features on
the layers. The -schema switch to ogr2vrt.py will create a VRT setup
this way.
Let me know if there are any questions or interest in this capability.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam,
[hidden email]
light and sound - activate the windows |
http://pobox.com/~warmerdamand watch the world go round - Rush | Geospatial Programmer for Rent
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