[gdal-dev] [GSOC] Support for m coordinates in OGRGeometries

[Even Rouault]

Selon Daniel Morissette <dmorissette at mapgears.com>:

> FWIW I think support for M would be a very welcome addition. An
> immediate use I'd see for it would be support for time on GPS tracks in
> GPX files.
>
> Note that if supporting the M dimension doesn't seem enough for a SoC
> project, making sure that all formats that support M (or as many as
> possible) are upgraded to properly implement it may very well fill the
> rest of the summer.

Good point. At least the following ones for sure support M: Shapefile, ESRI
Personal Geodatabase, FileGDB / OpenFileGDB, PostGIS (and PGDump and CartoDB),
Spatialite, GeoPackage
Likely (but not verified): GML, Oracle
Maybe: MSSQL, MySQL
And as pointed by Daniel, the GPX and KML / LIBKML drivers could also use the M
dimension for storing track times. Probably the GPSTrackMaker one also, but not
verified.
So indeed quite a few drivers to get familiar with!

>
> My 0.02$
>
> Daniel
>
>
> On 2015-03-17 9:04 PM, Even Rouault wrote:
> > Selon Edson Ticona <xcr33d at gmail.com>:
> >
> >> Hi
> >>
> >> I was looking for the ideas list on the site and found this one
> >> interesting: "Adding support for "M" dimension in OGR Geometries" but
> >> it's from 2014. Is it still relevant for the project? I searched on
> >> the code and it isn't implemented.
> >> For example, the class OGRGeometry needs the methods isMeasured,
> >> LocateAlong and LocateBetween according to the definition on the OGC
> >> simple standard. I couldn't find an ISO standard talking about M
> >> coordinates. Which one do you refer on the page?
> >> What do you think? Some feedback would be helpful.
> >
> > Edson,
> >
> > Yes it is still relevant. Perhaps SQL/MM Part 3 mentions it ? I didn't
> check.
> > You'll find the link to a draft doc on
> > http://trac.osgeo.org/gdal/wiki/rfc49_curve_geometries
> > What has been done in PostGIS might also be interested looking into.
> > M only might be a bit light for a whole SOC, so adding support for
> > POLYHEDRALSURFACE and TIN might also been interesting for completness (and
> full
> > PostGIS interoperability).
> >
> > Even
> >
>
>
> --
> Daniel Morissette
> T: +1 418-696-5056 #201
> http://www.mapgears.com/
> Provider of Professional MapServer Support since 2000
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