[postgis-users] newbie question and geometries?

[Jeff D. Hamann]

Hi,

Let me first apologize in advance for the newbie question, but I haven't
found a satisfactory answer to this question on the web yet, which is not
to say there isn't one. I just haven't found it yet. My simple question is
this:

I have two line geometries (e.g. roads and streams) and want to create a
layer of points where the two intersect. The simple query I've got is:

drop table culvert_locations;
create table
       culvert_locations
as
select
       Intersection( roads.segment, streams.segment ) as clvt
from
     roads, streams;

which returns the same number of rows as the roads table. It's a geometry
collection (I think) as evident by the the_geom field:

010700000000000000
 010700000000000000
 0101000000C36A11E61F789A4012108DEC17DA9340
 0101000000FAC5DC1431C19A407B94A5CFE4109440
 010700000000000000
 010700000000000000
 010700000000000000
 010700000000000000
 0101000000EAEBBE471202A240DE619E6B1B039B40
 010700000000000000
 010700000000000000
 010700000000000000
 010700000000000000


and when I attempt to export the points using:

pgsql2shp -f cullocs -r -u postgres ch1 culvert_locations

I get the following results:

pgsql2shp -f cullocs -r -u postgres ch1 culvert_locations
Initializing... type 'GEOMETRYCOLLECTION' is not Supported at this time.
The DBF file will be created but not the shx or shp files.
You've found a bug! (pgsql2shp.c:2864)
make: *** [sqldump] Error 1
jeff-hamanns-macbook-pro:ch1 hamannj$

Did I really find a bug, or am I not constructing the result table, and
thus the shapefile correctly. And on that note, I'm trying to maintain all
the data inside PostGIS (which rocks!) rather than having to export to
shapefiles, which are being used for the development.

Thanks, and please help.

Jeff.

-- 
Jeff D. Hamann, PhD
Forest Informatics, Inc.
PO Box 1421
Corvallis, Oregon 97339-1421