[postgis-users] Purpose of mesure value in 4D geoms

[strk at refractions.net]

On Fri, Apr 22, 2005 at 01:58:15PM +0200, Markus Schaber wrote:
> Hi, Jeremy,
> 
> Jeremy Palmer schrieb:
> 
> > Sorry if this seems to be a simple question but could someone explain
> > the use and purpose of the M value in the new lwgeom geometry structure.
> 
> You can use it for lean storage of measured values if you record geo
> coded measured values. E. G. with an XYZM geometry you can record
> position and height above ground and air pressure, or with an XYM
> geometry you can store longitude, latitude and fuel level of a ship.
> 
> The alternative is to use plain XY(Z) geometries and store the measured
> values into their own table columns.

Be aware that the Z value of a XYZ will probably have defined semantic
in upcoming OGC standards.

--strk;

> 
> Markus
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