[postgis-users] PointM, PolyLineM, PolygonM, ...

[Pierrick Brihaye]

Hi again,

strk at refractions.net a écrit :

> I'm with you,

Great !

> but quetions are:
> 
> 1) how should we import TypeM shapefiles ?
> 	a) as x,y,Z,m // wasting Z space in postgis 
> 	b) as x,y,z   // interpreting M as Z

I vote for a).

I don't know if it is a "waste" though :-)

> 2) how should we import TypeZ shapefiles ?
> 	a) as x,y,z,m // respecting shapefile meanings 
> 	b) as x,y,z,m // swapping M<->Z meaning

I think you mean :
  	b) as x,y,m,z // swapping M<->Z meaning

> 	c) as x,y,z   // discarding M
> 	d) as x,y,z   // using M, discarding Z

I vote for a)

> 3) how should we export geometry3d ?
> 	a) as TypeM // using M for Z values
> 	b) as TypeZ // wasting M space in shapefile

I vote for b) Let ESRI files carry the waste :-))

> 3) how should we export geometry4d ?
> 	a) as TypeZ // respecting shapefile meanings (4th dim -> M)
> 	b) as TypeZ // swapping M<->Z meaning

I vote for a)

BTW : how would you consider a missing Z coordinate ? A "null" (i.e. 
"not applicable") behaviour would be very nice, but wouldn't it make the 
stuff more complicated ?

Best regards,

-- 
Pierrick Brihaye, informaticien
Service régional de l'Inventaire
DRAC Bretagne
mailto:pierrick.brihaye at culture.gouv.fr
+33 (0)2 99 29 67 78