Using GDAL - Geospatial Data Abstraction Library and rgdal

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gdal

gdal url:​http://www.gdal.org/
is a translator library for raster geospatial data formats that is released under an X/MIT style Open Source license by the Open Source Geospatial Foundation. As a library, it presents a single abstract data model to the calling application for all supported formats. It also comes with a variety of useful commandline utilities for data translation and processing.
Cédric => What I've found at this site is not really helpfull, it is only python and c++ code.
url:​http://www.bostongis.com/?content_name=ogr_cheatsheet => Cedric: very good site !
url:​http://trac.osgeo.org/gdal/ Cedric : not really usefull

Below we suppose that you have the Qgis tool installed, so your path is C:\OSGeo4W Qgis has gdal included. Gdal comes with two main tools (executable files), the files for gdal are in

C:\OSGeo4W\share\gdal

call >cmd

C:\OSGeo4W\bin\ogr2ogr

or

C:\OSGeo4W\bin\ogrinfo

Translating .mdb into shapes outside ESRI

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" C:\base\basesig\Czhyd.shp C:\base\basesig\Czhyd.mdb

Cedric : this one works but warning there should be no space in the path (ex : no "document and settings/"...)

Conversion from PostGIS to ESRI Shape

adapted from url:​http://www.bostongis.com/?content_name=ogr_cheatsheet

The pgsql2shp and shp2pgsql are usually the best tools for converting back and forth between PostGIS and ESRI for 2 main reasons.

• It has fewer idiosyncracies when converting data.
• It has a lot fewer dependencies so can fit on your floppy.

If you really want to use Ogr2Ogr for this kind of conversion, below is the standard way to do it Here the example should export the table riversegments Cedric

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" C:\base\basesig\essai.shp PG:"host=localhost user=postgres dbname=CCM password=postgres port=5433" "riversegments"

Celine (pwd to be precised)

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" C:\base\basesig\essai.shp PG:"host=localhost user=postgres dbname=CCM password=PWD" "riversegments"

Cedric : celui ci marche mais j'ai eu du mal, ne marche pas une deuxième fois si les shape sont déjà crées dans le répertoire

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" C:\base\basesig\essai PG:"host=localhost user=postgres dbname=CCM password=postgres port=5433" "riversegments"

Cedric : OK marche de nouveau
Selecting specific fields, sets of data and Geometry
Sometimes you have more than one geometry field in a table, and ESRI shape can only support one geometry field per shape. Also you may only want a subset of data. In these cases, you will need to select the geometry field to use. The most flexible way to do this is to use the -sql command which will take any sql statement.

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" C:\base\basesig\essai1 PG:"host=locahost user=postgres dbname=CCM password=postgres port=5433" -sql "SELECT gid, the_geom FROM riversegments"

Cedric : ne marche pas, j'obtiens un message du type Unable to open datasource with following drivers, celui là on l'a très très souvent, j'ai essayé plusieurs trucs je ne comprends pas, la requete marche dans pgadmin

One way in which ogr2ogr excels above using the pgsql2shp tool is that ogr2ogr can export multiple tables at once. This is pretty handy for sharing your postgis data with others who do not have a postgis database.

The code below will export all your postgis tables out into a folder called mydatadump in ESRI shape (shp) format.

C:\OSGeo4W\bin\ogr2ogr -f "ESRI Shapefile" essai2 PG:"host=locahost user=postgres dbname=CCM password=postgres port=5433"

Now most of the time you probably only want to output a subset of your postgis tables rather than all your tables. This code exports only the neighborhoods and parcels tables to a folder called mydatadump in ESRI shapefile format ogr2ogr -f "ESRI Shapefile" mydatadump PG:"host=myhost user=myloginname dbname=mydbname password=mypassword" neighborhood parcels

rgdal

Similar content in rgal library in R but with less support
best site for help is url:​http://www.bostongis.com/?content_name=ogr_cheatsheet help for rgdal package url:​file:///C:/Program%20Files/R/R-2.10.0/library/rgdal/html/00Index.html