[geos-devel] PostGIS CVS has GEOS support

David Blasby dblasby at refractions.net
Wed Apr 9 14:54:14 EDT 2003

The PostGIS CVS now has GEOS support.

Here's some instructions.  The Makefile is a bit "iffy" right now until 
paul takes a look at it. 
So if things dont work for you they should fix themselves in a few days. 

a. this version of GEOS leaks memory very quickly (nothing is ever deleted)
b. using relate()-type function with a geometrycollection will throw an 
c. functions added are:  
  relate(g1,g2)  - returns the 3*3 matrix
  relate_pattern(g1,g2,pattern)  - returns true if relate(g1,g2) is 
'compatible' with pattern.
  overlaps(g1,g2)  - returns true if g1 overlaps g2
  contains(g1,g2) - returns true if g1 contains g2
  within(g1,g2)- returns true if g1 is  within g2
 crosses(g1,g2)- returns true if g1  crossesg2
 intersects(g1,g2)- returns true if g1  intersectsg2
 touches(g1,g2)- returns true if g1  touches g2
 disjoint(g1,g2)- returns true if g1 disjoint from g2
 isvalid(g)        - returns true if g1 is a valid geometry
These are defined in the OGC SF SQL specification - they are not always 
what you might think!

Here's what to do (EXACTLY like a normal postgis install)

0. install GEOS
1. get new postgis CVS
2. set PGSQL_SRC to your postgresql source (like normal)
3. make
    - if you have troubles compiling postgis_geos_wrapper.cpp,
      something like this should do the trick (with 2 warning):
      g++ -Wall postgis_GEOSwrapper.cpp -c -I/usr/local/include 

4. make install
5. create your database
6. install plpgsql language in your new database
7. install the postgis.sql file in your new database
8. TEST: upload the two new tables in postgis/regress/   
    psql geos2 < relate_test     555 relate() tests
    psql geos2 < isvalid_test    806 isvalid() tests
9. TEST: check results

    select relate(g1,g2),result, relate(g1,g2)=result from relate_test ;
    This should give 0 rows:
    select relate(g1,g2),result from relate_test where 
    select isvalid(g), result, comment from validtest ;   
    This should give 0 rows, but gives 7 because GEOS says
    repeated points are invalid, but JTS 1.3 says they are.
    This will be fixed soon.
    select g,isvalid(g), result,comment from validtest where isvalid(g) 
!= result;


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