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Re: [udig-devel] Seeking more direction from the uDIG community
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Murray,
Sorry, that rant was more particularly directed at Jesse, who sits about
12 feet from Kevin, and therefore knows how to find him. :)
Kevin can send you his PostGIS plugin for JUMP, which you can modify for
your needs.
Paul
Murray Richardson wrote:
Ok, thanks.
Who is Kevin and how can I contact him?
Murray
Paul Ramsey wrote:
What you need is a "SQLDataStore" that operates like Kevin's CWB
PostGIS plugin for JUMP. If you don't know what it is, please ask him
to demo it for you, it is the perfect combination of flexibility and
leverage of the GIS infrastructure. The SQLDataStore would take in a
SQL string, and database connection information and try to run it. If
the result set returned without error, and included a geometry, it
would map it. If it returned an error, it would verbosely report it.
Paul
Jody Garnett wrote:
Question for Cory;
Can we let the PostGisGeoResource resolve to a the JDBC connection
pool? That way Mr Richardson can just start coding with JDBC (which
he appears to be comfortable with).
Jody
Hello Community,
Thanks for previous help you've offered. I could use a bit more
direction if possible to determine whether I should carry on with
uDIG for a small project I am working on. I'm finding the uDIG
development learning curve to be a bit steep so far.
I've spent the last few days looking at uDIG (e.g. plugin tutorial
and all the other online resources) and I am trying to figure out
the simplest way to make use of powerful postgreSQL/postGIS
capabilities. Previously I was concerned with constructing spatial
queries on massive point data sets. These processes are easy if I
use a standard postgreSQL interface like psql or pgAdmin. It seems
like it should be a fairly simple task to construct plugins within
uDIG that make use of these and other RDBMS capabilities through
JDBC (if they don't already exist somewhere). I read an entry on
Cory Horner's community page about extending uDIG functionality to
incorporate better RDBMS capabilities. I am most definitely
interested in this because I am always faced with problems where
this type of capability would be an asset.
To give you an idea of the type of functionality I am interested in,
considering the following two examples:
(1) I am constantly using GIS and RDBMS capabilities separately
(loosely coupled fashion)for information management in the field of
hydrology. For example - I need to summarize the joint probability
distribution of land-use and soil types to determine an average
(lumped) runoff coefficient for nested watersheds (since runoff is a
function of landuse and underlying soil properties, among other
things). I do this by exporting the polygon intersection of a soils
layer, land-use layer and watershed layer to a RDBMS. Then I use
lookup tables to determine coefficients for individual landuse-soil
combinations and use an aggregate query to determine the mean value
for each watershed. It is nice to then join the mean value back to
the watershed layer and display this in a map. I also use the RDBMS
to do reporting of the individual intersected polygons by
watershed. This type of analysis and reporting is standard in flood
risk assessment and could be very easily streamlined with a tool
like uDIG and postgreSQL.
(2) Storing and accessing spatial-temporal hydrology data is an
emerging area of interest (consider the ESRI ArcHydro framework if
you're familiar with it) and an interesting direction for Open
Source GIS. For example, I would like to be able to store decades
worth of hourly streamflow data for numerous gauged weirs within a
postgreSQL DB and have this linked to a uDIG application that allows
me to extract the streamflow data by (e.g.) clicking on a point
station and entering a date. The query result could be just
exported to a text file for now. This capability would open the door
to a whole range of interesting spatial-temporal hydrology
applications (e.g. recession analysis, climate and streamflow data
interpolation, hydrologic model parameterization).
Based on these two particular examples, could someone perhaps direct
me on how to proceed to develop a very simple proof of concept for
enhanced RDBMS capabilities within a GIS environment? Consider
example 1 for instance - can I create a uDIG operation that is
accessed by right-clicking on 3 highlighted layers (like the
difference operation that is available when two layers are
selected). For my purposes I would like these to be postGIS
layers. The operation could then execute the postGIS intersection
procedure, the attribute join and the aggregate function all within
the postgreSQL service, and then map the results back to the
watershed layer for display in uDIG?
I know this is a fairly specific question, but what it boils down to
is, how do I access postGIS spatial operations as well as general
postgreSQL RDBMS functionality and non-spatial tables within the
uDIG environment?
Thanks in advance for any help. This project is for a small Open
Source/Open Access Student Experience program grant I am working on
through University of Toronto that involves developing a
proof-of-concept idea and some educational tutorials using
postgreSQL/postGIS. I would like to eventually be able to post the
results on my own uDIG community page if things go well. I think
this type of work could help open up uDIG capabilites to the
slightly less technical users like myself (e.g. GIS and basic
programming/RDBMS skills experience, but still need lots of examples
and explicit documentation to follow!).
Look forward to hearing back from someone - hope it's not too much
to ask over a mailing list!
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel