[gdal-dev] Does OGR support M values?

[Frank Warmerdam]

钱晓明 wrote:
> I find that OGR does not support M value in Geometry? So there is no way 
> to read M values in ESRI Shapefile? If I want, how can I handle this?

Kyle,

I believe that OGR does not support reading M values from shapefiles
at this time.  There has been discussion of providing a mechanism to read
it in place of Z or perhaps as a "list" attribute on the feature but
to the best of my knowledge neither of those approaches has been
implemented.

It is anticipated that at some point in the future OGR will advance to
the new OGC/ISO geometry model which includes "M" values for geometries.
I don't know when that might be though.

Shapelib does support reading M values if you are willing to program
against it's C API.

   http://shapelib.maptools.org/

Best regards,
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