[postgis-users] PostGIS user interface

[Phil Hurvitz]

The question of user interface should be driven by functional 
requirements. QGIS is a great all-around open source and free solution. 
gvSIG <http://www.gvsig.org/plone> is another free open source software 
that can handle analysis and cartography. ArcGIS probably has the most 
advanced combination of features for analysis and cartography, but 
doesn't come cheap and in my experience tends to be very slow when using 
PostGIS tables as the data source.

I'll put a plug in for OpenJUMP <http://www.openjump.org/> for very fast 
but fairly rudimentary displays of PostGIS data. Most of our work is 
focused on 2D vector data analytics, most of which we do using R and 
PostgreSQL/PostGIS. Although we have ArcGIS, we use it less and less for 
analytics (but we still use it for making the best looking maps and for 
some of the analytic functionality that is faster/easier in Arc).

The *drawback* to OpenJUMP is that to load data from the db, some SQL 
needs to be written in the interface, e.g., for a table called 'layer' 
with one geometry column, this works to just draw the shape data and 
load the attributes as a table:

SELECT * FROM layer;

The main *benefit* is the same as the main drawback: some SQL needs to 
be written. This means you can do analytics on the fly and have them 
shown in the map display without needing to store any files or tables. 
For example, to create a set of day-level aggregate convex hulls in 
projected units from a set of GPS points stored in a table called 'gps' 
that also has a 'time_gps_utc' column enumerating the timestamp for each 
record, and shape data stored in two columns 'the_geom_2926' and 
'the_geom_4326' (WA State Plane N and lat/long WGS80, respectively):

select count(*) as npoints,
st_area(st_convexhull(st_collect(the_geom_2926))) AS area_ft2,
extract (doy from time_gps_utc) AS jday,
st_convexhull(st_collect(the_geom_2926))
from gps_10100590 group by
extract (doy from time_gps_utc)
order by jday;

I can view, pan/zoom/identify the data to get an interactive check of my 
analytic result. Most interactive GIS software assumes what will be 
displayed in the map display has a file or tabular source. With 
OpenJUMP, if you don't like what you see, just close out--there are no 
intermediate tables or files to delete. If you like what you see, then 
you can easily modify the SQL and make a permanent data set, e.g., to 
create a table in your db:

create table foo as
(select count(*) as npoints,
st_area(st_convexhull(st_collect(the_geom_2926))) AS area_ft2,
extract (doy from time_gps_utc) AS jday,
st_convexhull(st_collect(the_geom_2926))
from gps_10100590 group by
extract (doy from time_gps_utc)
order by jday);

or use pgsql2shp to create a shapefile from the query without needing to 
create an intermediate table:

pgsql2shp -f /tmp/foo mydb "select count(*) as npoints,
st_area(st_convexhull(st_collect(the_geom_2926))) AS area_ft2,
extract (doy from time_gps_utc) AS jday,
st_convexhull(st_collect(the_geom_2926))
from gps_10100590 group by
extract (doy from time_gps_utc)
order by jday;"

The input data sets needn't even be stored as tables. For example, using 
the ST_ConvexHull example in the PostGIS docs, you can view the created 
shapes.

SELECT ST_ConvexHull(
ST_Collect(
ST_GeomFromText('MULTILINESTRING((100 190,10 8),(150 10, 20 30))'),
ST_GeomFromText('MULTIPOINT(50 5, 150 30, 50 10, 10 10)')));


Getting used to doing things this way is a bit difficult for a user 
whose main experience is with typical GIS software. But the gain in 
efficiency in adaptive tweaking of analytics, coupled with the lack of 
having to deal with the multiple intermediate junk data sets typically 
resultant from GIS workflows is quite refreshing.

-- 
-P.

**************************************************************
Philip M. Hurvitz, PhD | Research Assistant Professor | UW-CBE
Urban Form Lab  | 1107 NE 45th Street, Suite 535  | Box 354802
University of Washington, Seattle, Washington  98195-4802, USA
phurvitz at u.washington.edu | http://gis.washington.edu/phurvitz
"What is essential is invisible to the eye." -de Saint-Exupéry
**************************************************************

> From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of rkoehler at excellandservices.com
> Sent: Tuesday, February 25, 2014 8:02 PM
> To: postgis-users at lists.osgeo.org
> Subject: [postgis-users] PostGIS user interface
>
> Hello,
>
> Are there versions of PostGIS that can be used as a database input interface to capture land owner information for Land Acquisition companies? (Right-of-Way acquisition).  Our right of way company is looking for a GIS solution is which we can capture GPS coordinate data, land owner information easement documentation, notes, etc. and attach it to specific parcels, so that when we click on a parcel the data will pop up.  e.g. easement document.
>
> Thank you,
> Robert 651-210-9111<tel:651-210-9111>
>
>
> Robert Koehler
> Senior Siting and Land Rights Agent
> Excel Land Services
> rkoehler at excellandservices.com<mailto:rkoehler at excellandservices.com>
> 651-253-0003