[postgis-users] Map Simplification Program howto use it or is it exist any better alternative?

Maciej Sawicki viroos.pl at gmail.com
Fri Feb 12 07:18:20 PST 2010


Hi,
I want to simplify complex shp file. I will probably use something
like DP algorithm
(http://en.wikipedia.org/wiki/Ramer-Douglas-Peucker_algorithm). But
when using DP algorithm for different points sets, common points can
be treated differently and this causes empty space between polygons.
To avoid this I need to use algorithm separately for different
sections.

I tried do it my self with help of geotools but I stumbled into this
project: http://www.cartoweb.org/downloads/vertexsimplification/documentation.html.
Unfortunately I don't have much experience with relational databases
and I don't heave any expedience with postgis.

I tried to simplify this shp:
http://efele.net/maps/tz/world/tz_world.zip. I installed postgis and
imported my shp. This is my db:

 Schema |         Name         |   Type   | Owner
--------+----------------------+----------+--------
 public | geometry_columns     | table    | viroos
 public | spatial_ref_sys      | table    | viroos
 public | tz_world_org         | table    | viroos
 public | tz_world_org_gid_seq | sequence | viroos

I use this command: python vertex.py -H localhost -u viroos -p
password -d simplify2 -v public -t public.tz_world -i gid -g geom -m
100000

but I get this error:

Vertex Table Generation
Traceback (most recent call last):
  File "vertex.py", line 393, in <module>
    main()
  File "vertex.py", line 380, in main
    vertex(schemaVertex,tableIn,colGeo,colId,dmin)
  File "vertex.py", line 46, in vertex
    populateVertex(vertex,sequence,colId,colGeo,tableIn,dmin)
  File "vertex.py", line 105, in populateVertex
    geometryType= s[0][0]
IndexError: list index out of range


I got no idea what I do wrong :(.

I will appreciate any help with this.
Also if there is exist any better alternative for doing this I would
like to hear about it.

TIA for help.

Best regards,
Maciej Sawicki



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