[GRASSLIST:4984] Re: PostGrass Italian C driver

Radim Blazek blazek at itc.it
Mon Nov 18 04:47:42 EST 2002

On Friday 15 November 2002 03:47 pm, Juanse wrote:
>   Hi everyone
>   I am a new comer onto Grass.
>   I am migrating from Mapinfo stuff to OpenSource. I have succesfully
> migrated all my data to PostgreSQL/PostGIS and I can serv it with Mapserver
> (UMN), now I need to join Grass with PostgreSQL/PostGIS.
>   Searching the web I have arrived to an italians students page decribing
> in detail a C driver call PostGrass, but I can only arrive to pdf files.
> http://www.rcost.unisannio.it/antoniol/students/PostGrass.
>   I wonder if there is a place to download this driver or they come already
> installed on GRASS 5.1?
>   Your help will be cordially wellcome
>   TIA
>   Juanse
>   Temuko-Chile

PostGrass is in GRASS 5.1 sources and it should be compiled in downloadable
binary, BUT!!!:

1) Grass 51 is experimental version, not yet ready for users.
2) PostGrass is not fully compatible with PostGIS (Simple feature
   specification) because Grass uses topological model for areas and
   SFS does not. That means that it is possible to use lines and points
   from one database in Grass and Mapserver, but not areas. PostGrass
   is intended for multi user enviroments where more users must edit large
   maps simultaneously.
3) For read only access to PostGIS, "fully" compatible (pseudotopology) with
   SFS, OGR support (includes PostGIS) is planned, which will handle areas
   also. This should not be difficult, shapefiles in Grass51 work in such
   way, C interface in OGR was added and in fact one student already works
   on that (I hope).
4) Note: it is not driver, PostGrass is optionaly compiled into vector
   library and modules.

Testers are VERY welcome of course, but you must be patient and have enough


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