[postgis-users] How do you use PostGIS?

[Mike Leahy]

Hello list,

Here's some info about the EduCal project I've been working on over the past two
years:

- Name of organization:
University of Waterloo (Waterloo, Ontario, Canada), and Alternativa (San Martin
de Porres, Lima, Peru)

- Data being managed in the database: 
Eduction quality and social well-being ndicators derived from education and
population census data, linked with spatial features (e.g., schools, city
blocks, districts, etc...)

- How the data is being accessed / manipulated: 
A 4-step analysis tool has been designed for users to be able to assess
education quality.  The first step allows users define their areas of interest
for analysis.  This first step allows users to select political regions using a
list-based interface, with the option to select from the lowest level of
political boundaries (districts) from a map interface.  In the map interface
(which uses MapServer, Rosa, and some MapLab-generated code), users may draw
shapes which are submitted to the application and queried against the districts
layer in PostGIS to add or remove districts from the selection set.

The second step allows the user to select indicators for their analysis from the
data that are stored in the PostgreSQL database.  The third optional step allows
users to define parameters to calculate an overall index that represents a
measure of education quality or social-well being.

The final step and allows the user to view output in tabluar form, or in map
form using the MapServer/Rosa viewer.  When displayed in map form, the tabular
indicators and calculated indices (if applicable from step 3) are linked to
spatial features in PostGIS tables and displayed as classfied tematic maps.

Current work is underway to enhance the map-based tools for selecting areas of
interest and viewing analysis results using a Chameleon-based interface that
makes use of PostGIS spatial processing functionality.

- Why we chose to use PostGIS for the application:
As this project is intended to be sustainable in the developing country of Peru,
Open Source tools were the first options we explored.
The tool required software with the capability of dynamically generating tabular
results, associating those results with spatial layers, and providing a
web-enabled interface to view and interact with maps...PostGIS combined with
MapServer fit both of these requirements perfectly.

- What PostGIS features or PostGIS-related software would make life much
easier/better?
A user-friendly desktop gis tool for generating cartographic maps from PostGIS
data: Quantum GIS is pretty good, but still has some kinks to work out, and
would be nice if a new binary were released with the patch for PostGIS 1.0. 
uDig is also good, except it has very limited options for displaying PostGIS
data (e.g., there are no options for classifying features from PostGIS layers
based on attribute data, or linking PostGIS layers to data in non-spatial
tables).  Without an easy-to-use client for viewing PostGIS data and creating
printable cartographic maps (besides manually creating MapServer web pages),
PostGIS can be somewhat cumbersome when all I might want to do is quickly
visually examine a map layer and its attributes and/or generate a printable map.
 If there is another tool out there that already does this relatively easily,
perhaps someone could correct me.

Dumping PostGIS layers to shapefiles using the pgsql2shp utility would be a bit
handier if it included a projection file with the output when the exported
PostGIS table has a valid SRID associated with it.

=========================

The EduCal website, avaiable in both English and Spanish, is currently hosted
from the Alternativa server at http://www.alter.org.pe/educal, and from the
University of Waterloo development server, http://gaia.uwaterloo.ca/educal.  The
UW server tends to have the latest-and-greatest changes to the site (it is
currently stable, but not always), and will likely have a faster connection for
most users outside of Peru.

For additional information about this project, feel free to contact me.

Of course, I would like to thank the developers of PostGIS and all of the Open
Source tools that have made this project possible, as well as those who have
volunteered time to produce and distribute binaries and documentation for many
less experienced users.  I would also like to thank the many users and
developers who help provide support through through the user email lists. 
Together, you are significantly enhancing the capacities of many people around
the world that might otherwise be left behind.

Micheal Leahy


Quoting Paul Ramsey <pramsey at refractions.net>:

> PostGIS'ers:
> 
> The time has come again for my annual query of our list. The last time 
> I asked this, about a year and a half ago, there were ~260 people on 
> the list. This time, there are ~600 people. So by one metric at least 
> we are growing quickly in numbers. We also have ~1200 source code 
> downloads a month these days, up from ~350.
> 
> Anyhow, the question is this:
> 
>     "How are you using PostGIS in your organization?"
> 
> I am preparing for the Open Source Geospatial conference in Minnesota 
> (http://mapserver.gis.umn.edu/mum/) and would like to get a feel for 
> what people are doing these days with PostGIS?
> 
> If you could say in your response, at a minimum:
> 
> - Name of the organization
> - Data being managed in the database
> - How the data is being accessed / manipulated
> - Why you chose to use PostGIS for the application
> 
> And also for our edification and strategic planning:
> 
> - What PostGIS feature or PostGIS-related software (not necessarily 
> internal to PostGIS) would make your life much easier/better?
> 
> Thanks so much!
> 
> Paul
> 
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
> 




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