[postgis-users] ArcGIS 8 connecting to Postgis

[Nicolas RIBOT]

Hi all,

We saw on the list questions about ArcGIS 8 and Postgis (for instance,
thread: 
Re: [postgis-users] How to PostGIS + Map Objects + Delphi)

Paul explained that it is not easy to develop a real ArcObject driver to
allow postgis to be another valid datasource for ArcView. It requires a
lot of development.

Wanting to learn more on the ArcObject data model, we decided to begin a
little project to connect to postgis databases and retrieve objects
directly in ArcGIS8.

The very first version allows:

	• To list all ODBC DataSourceNames using the postgresql driver
	• To see the geographic tables available on the datasource (for
each table: database name, table name, geo column name, geometric type,
projection system and number of geometric objects are listed)
	• To choose one or several tables and to dump them into arcGIS
(Tables are then loaded locally into shapefiles and available in
ArcView.)
	• To load modified shapefile back to postgis.

It is composed of VBA code stored in a template document (.mxt) that
adds 2 buttons on the toolbar: one for dumping from postgis to arcgis,
one for loading back from arcgis to postgis.

Performance is not very good: it takes about 2 minutes to load a table
containing 29000 polygons (the corresponding shapefile size is 25 Mb).
This is due to the WKT parsing that could be improved.

The next version of this code will include:
	• Possibility to add or remove attributes fields in the
shapefile and to update/alter geographic tables accordingly.
	• An improved type mapping between SQL types and VB ADO types
	• The projection system management, as ArcGIS uses OpenGIS WKT
representation for spatial reference systems,
	• An improved user interface with more options
	• Internationalization of the user interface (it is only in
French for the moment !!)
	• Making a dll instead of a .mxt project to hold the code.


If some of you are interested in this development, you can send me an
email (nicolas.ribot at scot.cnes.fr)

Also is available an internet application allowing to manage shared geo
information (shapefile, postgis DB, rasters):
http://scot.ataraxie.fr:8080/geonline/

Nicolas Ribot
SCOT