Connecting Qgis to an Ecosur based POSTGIS server

The internet connection speed from Ecosur is unfortunately extremely slow. We have a limited number of external IPS. In order to set up a temporary trial POSTGIS server I had to commandeer a PC that is also being used for image processing. So there is only limited and intermittent connectivity. It would fail completely if many users connected at the same time.

However I aim to put some of the most useful basic coverages for Chiapas and Mexico on this server as an alternative to passing around shapefiles. One advantage is that everything is held in the same projection using the same datum (EPSG code 4326, PROJ4 +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
ESRI GEOGCS[“GCS_WGS_1984”,DATUM[“D_WGS_1984”,SPHEROID[“WGS_1984”,6378137,298.257223563]],
PRIMEM[“Greenwich”,0],UNIT[“Degree”,0.017453292519943295]]

Import to POSTGIS requires clean topology. I have unfortunately found that many of the available layers have problems with this and do not import cleanly. I am trying to fix by cleaning them in GRASS but it is tedious and does not always work. However the layers I do get into the system are then guaranteed to be usable by any software.

The easiest way to connect to the server is to download Qgis (available for windows here http://download.qgis.org/downloads.rhtml – choose a stable version)

Once Qgis is running choose “add a postgis layer”.

Connect to the server with the details shown below (The password is available by contacting me directly to avoid over use and details such as the name of the database may change).

suelos2.png

Then layers can be loaded strait into Qgis. For example the 1:25000 soils map for Mexico can be downloaded by choosing the layer shown below.

suelos.png

This can then be saved locally as a shapefile by right clicking on the name of the layer in the panel on the right. I have also had problems with encoding (bad characters) as most of the dbf files are not in UTF8. I am working on this. Again the advantage is that once everything is done there are no future problems.

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