[gdal-dev] Call for discussion about RFC 61: Support for measures in geometries

[Jukka Rahkonen]

Ari Jolma <ari.jolma <at> gmail.com> writes:

> Should storing data, with measures, into a format, which does not 
> support measures, remove M values from the data? This would be similar 
> to the current behavior with curved geometries and formats which do not 
> support them.
 
I wonder what should happen when GDAL creates new vertices. It does not seem
to be clear even with XYZ as can be seen from this example:

Take LINESTRING ( 184 389 0, 858 346 100 )
Run ogr2ogr with -segmentize 1

Result: The first vertex of the new linesting has Z=0, all the other
vertices have Z=100.

With XYZ data users might be happy if Z value gets interpolated just like X
and Y but for measurements it could be not desired at all. Does M dimension
support anything like NoData?

There must be also other cases when GDAL can create unexpected M values but
probably we can only warn users about that in the documentation.

-Jukka Rahkonen-