[GRASSLIST:4964] PostGrass Italian C driver

Juanse · November 15, 2002, 2:47pm

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

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Radim_Blazek · November 18, 2002, 9:47am

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
courage.

Radim

Juanse · November 20, 2002, 11:57pm

Where can i get more información on the Grass Data Model used for areas, or
the Grass data model in topological terms?

Is the Grass Data Model compliant with OGC standards, or will the OGC data
model standards evolv to Grass Data Model?

Thanks

Juanse
temuko-Chile

> I know that Geos (Topological PostGis) is almost finish, and after your
> reply the same applies to Grass.

Note that I used word "topological" in quite different sense than it is

used

in Geos. In Geos it means topological operation between simple features
and in Grass I was talking about data model used for areas (boundaries +
centroids, not closed polygons).

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Eric_G_Miller · November 21, 2002, 2:45am

On Wed, Nov 20, 2002 at 08:57:54PM -0300, Juanse wrote:

Where can i get more información on the Grass Data Model used for areas, or
the Grass data model in topological terms?

Is the Grass Data Model compliant with OGC standards, or will the OGC data
model standards evolv to Grass Data Model?

No, the OGC Simple Features specification is not compliant with the
GRASS data model (see, first we take a shapefile, give it a new
name ...).

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Radim_Blazek · November 21, 2002, 3:18pm

On Thursday 21 November 2002 12:57 am, Juanse wrote:

Where can i get more información on the Grass Data Model used for areas, or
the Grass data model in topological terms?

Grass 5.0 Programmer's Manual, 6.7 Vector Topology Rules

Is the Grass Data Model compliant with OGC standards, or will the OGC data
model standards evolv to Grass Data Model?

No.

Radim

jprs · November 21, 2002, 4:09pm

> Is the Grass Data Model compliant with OGC standards, or will
the OGC data
> model standards evolv to Grass Data Model?

No.

What about the other way round? Will GRASS comply with OGC standards?
If the question makes any sense.

Regards,
Juan

Bernhard_Reiter · November 22, 2002, 10:01am

On Thu, Nov 21, 2002 at 05:09:05PM +0100, jprs wrote:

> > Is the Grass Data Model compliant with OGC standards, or will
> the OGC data
> > model standards evolv to Grass Data Model?
>
> No.

What about the other way round? Will GRASS comply with OGC standards?
If the question makes any sense.

For the internal data model,
OGC compliance is not desirable IMO.
Because the internal data model is just this "internal".

If you talk about access layers, this is a completely different
question.

Radim_Blazek · November 26, 2002, 6:47pm

On Monday 25 November 2002 12:39 am, you wrote:

Hello Radim,

Also, it would be nice to be able to edit more than one map, or layer, at a
time. For example, if I move a parcel line, that line may also define a
municipal boundary stored in a different map (or layer). If I update parcel
line, I would like to also have the municipal boundary update.

Rich

If one line represents more features, it should be realy only one line in
GIS, unfortunately we cannot mix more area layers in one map. If your
municipal boundary would be road (as line) or river centerline, it could be
represented by one line in one vector. I know that it is not solution for the
problem you are talking about.

Radim