[postgis] Development Roadmap

[Nicolas Ribot]

Hello everybody,

In the attempt to provide a global solution for delivering
geographic maps and information on the internet, we
have developed a solution based on MapServer to generate
interactive maps in browsers.

This solution uses a lightweight java applet and Javascript
objects on the client to display the map.
The question of storing geographic data in a relationnal-object
database, and using these objects directly to
produce maps was obviously crucial, but not very
straightforward: Existing solutions (Oracle spatial, DB2
spatial cartridge, Esri SDE, etc...) are expensive, difficult
to use, and not very efficient.

We decided to use a SQL92-compliant DB schema to store
geographic objects coordinates in the database, and to
dump data into shapefiles on-the-fly (performance was good
enough for our applications, with small geographic
objects).

After having seen the great potential of PostGis, and tested
very briefly the performance, we have immediatly
decided to use PostGis for the storage of geographic data:
(the test consisted in loading (shp2pgsql), and displaying with
MapServer all the french cities (36646
polygons). The performance was really astonishing, even when
building dynamic spatial query with PostGIS/OpenGIS
operators).

We would like to provide a framework based on OpenSource code
to ease the handling of geographic data and their
use on the internet:

    - An HTML application to display maps, navigate, select
layers, query objects, etc... (done)

    - A DB schema to store MapServer MapFiles in the database.
(done)

    - A tool (php) to parse and load existing mapFiles into the
DB schema, and to dump the schema into a MapFile
(done)

    - A geographic data loader interface to shp2pgsql
(html/php) to populate the DB with existing data from
files (currently shapefile, but later other geographic formats
by adding a conversion tool before shp2pgsql (FME
for ex.))
This interface allows to browse for raster files and registers
them in the Database, in a raster table storing
spatial extent, raster name, acquisition date, description, and
file path to the raster.
(done, very first version...)

    - A layout manager (html/php), allowing to choose which
data will compose the map, and the graphic layout
associated with the data (=> generation of a new mapFile) (NOT
done)

    - An application generator (html/php) to compose the
end-user html page presenting the map. (not done)
    - We would also like to provide, in the future, interfaces
allowing to make geographic queries directly on
the internet.

This project is just beginning: there is no internet demo yet
available.

We also have some experience about OpenGIS Simple Feature
Specifications gained when developping an
OpenGIS-compliant spatial cartridge for DB2 and Oracle (SRText
format, metadata schema, spatial operators).

As requested for PostGIS 0.6, we can also provide Spatial
Reference Text (SRTEXT) for European projections and
UTM zones:
    UTM zone 5 to 60, North and South
    WGS 84 Lat Long
    Lambert conformal conic (french projection),
    Swiss Projection on 1937 and 1903 datums
    Gauss-Kruger zone 1 to 5 on Bessel and Krasovsky ellipsoids
(german projections)

Regards, and congratulations for PostGIS extension !

Nicolas Ribot - nicolas.ribot at scot.cnes.fr
Jerome Gasperi - jerome.gasperi at scot.cnes.fr




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