[gdal-dev] PGeo: reading circular arcs - how?

[Stefan Keller]

Hi all

I have an ESRI Personal GeoDatabase .mdb file (PGeo) which I would
like to read and convert e.g. to Shapefile.
The PGeo file contains "circular arc"s (or circular curve) and since
OGR only supports linestrings they should be segmented (similar to
http://www.gdal.org/ogr/drv_ili.html ).

Now it turned out that the output is wrong: It seems that at least the
midpoint(s) are misinterepreted.

In fact, when looking at the source (line 430 ff.) there's a TODO there:
http://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogrsf_frmts/pgeo/ogrpgeolayer.cpp

ESRI user doc says at
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//002t0000000m000000.htm
"Circular arc curves use a mathematical formula to draw the curve. If
you export a geodatabase feature class containing circular
arc curve features to a shapefile, the curved features are transformed
to simple line features with closely spaced vertices to capture the
curved shape".

=> Does anybody know this formula  and/or the meaning of the
additional attributes in the byte stream?

Yours, S.