[gdal-dev] ogr2ogr problem converting UK Ordnance Survey MasterMap

[Peter J Halls]

Dear All,

    as a step towards a solution where the output is to Oracle, I have just 
submitted enhancement ticket 3690.  This describes edits to ogrocidatasource and 
ogrocitablelayer to enable the creation of non-spatial tables (ie omitting the 
geomentry column) if a geometry type of wkbNone is specified to CreateFeature. 
I've tested this in 1.6.3.

    Doing this facilitates the use of separate tables for the problematic OS 
data, so, for example, changeHistory entries could be written to a changehistory 
table, specifying the FID of the master record and the change history data (date 
and reason) as three columns.  The result could be joined to the master by means 
of the FID whenever there is interest in these data.  My thanks to Dale Lutz for 
suggesting this type of approach.

    The same approach can be used for storing the contents of an OS Mastermap 
ITN dataset - which comprises a set of spatial and non-spatial datasets, each of 
which may include the problematic columns.  Indeed, handling ITN will be a 
little more complex than with Topography Layer, as there will be a need to 
differentiate between the extra tables comprising such data as changeHistory.

    Note that this in no way breaks the principle that GDAL does not handle 
topology: any joins or inferred relationships between any of these tables is in 
the mind and usage of the programmer / end user.  All I have done is facilitate 
the writing of these data into a simple output format.  I do see other benefits 
in these changes: for example when writing models that must use both spatial and 
non-spatial data: this was easy with Shapelib / DbfLib and means that the 
programmer need only use the OGR api to work with Oracle tables.

Best wishes,

Peter

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Peter J Halls, GIS Advisor, University of York
Telephone: 01904 433806     Fax: 01904 433740
Snail mail: Computing Service, University of York, Heslington, York YO10 5DD
This message has the status of a private and personal communication
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