Re: [postgis-users] Exporting 3D Shape to PostGIS

Kevin Neufeld Fri, 08 Feb 2008 09:46:52 -0800

Hi Matthew,

Yes. PostGIS actually supports a 4th dimension, measures, which itlooks like your ogr utility program populated with '0'.

You may be interested in these methods to verify this yourself.
ST_zmflag(geometry),
ST_ndims(geometry),
ST_Force_3d(geometry),


ie.
SELECT asewkt(force_3d(the_geom)) from streets_3d where gid=1;

Cheers,
Kevin

Matthew Pulis wrote:

Hi Kevin and the rest :)

Seems like it did the trick :

select asewkt(the_geom) from streets_3d where gid=1;

"MULTILINESTRING((625304.649659493 214113.544271209 111.1573080888
0,625301.199687227 214078.520974251 111.1573080888 0,625299.489760683
214056.176602372 111.1573080888 0,625299.289850496 214050.649031119
111.1573080888 0))"

As opposed to :

select asewkt(the_geom) from streets where gid=1;

"MULTILINESTRING((625304.649659493 214113.544271209,625301.199687227
214078.520974251,625299.489760683 214056.176602372,625299.289850496
214050.649031119))"

I can take it that 111.1573080888 is the altitude right? (considered as z

coordinate)

Am I right in my supposition?

Thanks a lot for your help :)

Matthew

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Kevin
Neufeld
Sent: Friday, February 08, 2008 5:49 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Exporting 3D Shape to PostGIS

http://postgis.refractions.net/docs/ch06.html#id2615538

ST_AsText(Geometry) returns the WKT representation according to OGCstandards, which does not include 3D values.


Try PostGIS's WKT extension instead: ST_AsEWKT(Geometry)

Cheers,
Kevin


Matthew Pulis wrote:

Hi,

I have a 3D Shapefile, which I am trying to export to a PostGIS table.

This is the an extract from the ogrinfo on the shape file :

[EMAIL PROTECTED]:~$ ogrinfo -so streets3d_new_shps/ testogr

Geometry: 3D Line String

Feature Count: 49746

Extent: (610869.384850, 196653.348553) - (676816.248304, 258102.572101)

Layer SRS WKT:

PROJCS["Lambert Conformal Conic",

    GEOGCS["grs80",

        DATUM["North_American_Datum_1983",

SPHEROID["Geodetic_Reference_System_1980",6378137,298.257222101]],


        PRIMEM["Greenwich",0],

        UNIT["degree",0.0174532925199433]],

    PROJECTION["Lambert_Conformal_Conic_2SP"],

I exported this shapefile to PostGIS table and this is the result of this

query :

select astext(the_geom) from streets_3d where gid=1; :

"MULTILINESTRING((625304.649659493 214113.544271209,625301.199687227
214078.520974251,625299.489760683 214056.176602372,625299.289850496
214050.649031119))"

And this is the resulting query from the streets table which is the normal
2D table :

select astext(the_geom) from streets where gid=1; :

"MULTILINESTRING((625304.649659493 214113.544271209,625301.199687227
214078.520974251,625299.489760683 214056.176602372,625299.289850496
214050.649031119))"

Any idea what I can do so I can start using elevation on this table

please?

Any help will be extremely appreciated

Regards

Matthew

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Re: [postgis-users] Exporting 3D Shape to PostGIS

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