Worskhop Leicester 2010

Beyond Google Maps and Mashups

Practicalities

●Download:
www.archaeogeek.com/downloads/leics2010.zip

Save to /home/user and extract
●

/home/user/leics2010 folder should then contain:
●

shape_files (folder)
demo.map
mapserver.html
baselayers.html
leicester_2010_notes.pdf

Installing Quantum GIS plugins

Needed Plugins: Mapserver Export, PostGIS
manager, SPIT

Databases

+
www.postgresql.org
postgis.refractions.net
● Server-based database (not like access)
● Data is entirely separate from user interface
● Inside the database, data stored in schemas
for finer control

How to connect to a database

● HOST: localhost, 192.168.3.40, myserver.com
● DATABASE: ??? (your choice)
● USERNAME: user
● PASSWORD: user
● PORT: 5432 (default)

Getting spatial data into PostgreSQL

● OGR2OGR (command line)
● SHP2PGSQL (command line)
● SPIT plugin for Quantum GIS
● Essential Parameters:
host, username, password, dbname,
port (as before)
● Additionally: name and location of
shapefile, name of table in database,
coordinate system of data

Loading data with SPIT

Create new database with pgadmin3
and connect to it with SPIT in QGIS

SPIT (continued)

Make “DB Relation Name” all lower case!!!

Database house-keeping

● Each table should have a primary key
● Each spatial table should be recorded in
the geometry_columns table
● Each spatial table should have a spatial
index
CREATE INDEX yourtable_idx ON
yourtable USING
GIST(geometry_column);

Querying data
● SQL: Structured Query Language
SELECT some comma de-limited
columns FROM your_table WHERE
some condition is met;
● Use PSQL from command line, PgAdmin3,
or PostgreSQL Manager/SQL Editor
● SQL is case-sensitive for table and column
names, and keywords are usually in
capitals

Querying data
● Display on the map using CREATE VIEW
AS:
CREATE VIEW viewname AS SELECT
* FROM united_kingdom_counties
WHERE...
● Add to QGIS using Add Layer/Add
PostGIS layer

Spatial Querying

● Find out which county a point is in:
SELECT “PROV3NAME” FROM
united_kingdom_counties WHERE
st_within(geomfromtext('point(-1.4
52.6)', 4326), the_geom);
● Find out the spatial extent of your data:
SELECT st_extent(the_geom) FROM
united_kingdom_counties;

Types of Map Server

● cgi program on a web server.
Configuration via text files

● java-based program. Configuration via
web interface

The Map File
MAP
NAME "sample"
STATUS ON
SIZE 600 400
EXTENT -180 -90 180 90
UNITS DD
SHAPEPATH "../data"
IMAGECOLOR 255 255 255
WEB
IMAGEPATH "/ms4w/tmp/ms_tmp/"
IMAGEURL "/ms_tmp/"
END
LAYER
NAME 'global-raster'
TYPE RASTER
STATUS DEFAULT
DATA bluemarble.gif
END
END

Checking and Viewing a map file

● SHP2IMG at the command line
shp2img -m
/home/user/leics2010/demo.map
-o /home/user/demo.png
● With a browser
http://localhost.com/cgi-
bin/mapserv?
map=/home/user/leics2010/demo.map
&mode=map

Adding new layers to a mapfile
LAYER
NAME "your layer"
STATUS DEFAULT
TYPE POLYGON
DATA "yourshapefile.shp"
CLASS
NAME "your name for this symbology"
STYLE
SYMBOL 0
OUTLINECOLOR 0 0 0
COLOR 207 150 123
END
END
END

Connecting to PostgreSQL from Mapserver

LAYER
NAME "UK Counties"
STATUS DEFAULT
TYPE POLYGON
CONNECTIONTYPE POSTGIS
CONNECTION "host=localhost port=5432
dbname=osgis2010 user=user password=user"
DATA "the_geom from united_kingdom_counties"
CLASS
…
END
END

Displaying single layers

● Set the Layer status to “ON” rather than
“DEFAULT”
● Specify the layers as part of the URL:
http://localhost/cgi-
bin/mapserv?
map=/home/user/leics2010/demo.
map&layer=counties

Web Mapping: Practicalities

● Make the web folder writeable
sudo chown -R user /var/www
sudo chmod -R 755 /var/www
● If asked for a password, it's user

Structure of a web page

<html>

<head>
<title> My Home Page
</title>
</head>

<body>
HELLO WORLD!
</body>

</html>

Scripting

● SERVER-SIDE:
php, asp
<?php
phpinfo();
?>
● CLIENT-SIDE:
javascript

Solving Problems using Firefox

OpenLayers page structure
<html>
<head>
<script src="..lib/OpenLayers.js"></script>
<script type="text/javascript">
var map, mylayer;
function init() {
map = new OpenLayers.Map('map');
mylayer = new OpenLayers.Layer.MapServer( "World Map",
"http://localhost/cgi-bin/mapserv.exe",
{map: 'C:/world_mapfile.map'});
map.addLayer(mylayer);
map.zoomToMaxExtent();
}
</script>
</head>
<body onload="init()">
<div id="map" style="width: 600px; height: 300px"></div>
</body>
</html>

Adding Controls

Scale Bars, Permalink
and Mouse Position

Layer Switcher and
Overview Map

Base Mapping
● Can use base data from Google, Microsoft,
Yahoo, Openstreetmap, etc
● Specify base layer (not always necessary)
{'isBaseLayer': true}
● Overlay needs to be transparent
{'transparent':true, 'format':
png}
● Change addlayers directive
map.addLayers([layer1,layer2]);

Beyond OpenLayers

•MapGuide Open Source
http://mapguide.osgeo.org
•Mapfish http://mapfish.org/
•Mapchat http://mapchat.ca/
•Featureserver http://featureserver.org/

And Finally...

Have fun!!!

This work is licenced under the Creative Commons Attribution-Share Alike 2.0 UK: England & Wales License. To
view a copy of this licence, visit http://creativecommons.org/licenses/by-sa/2.0/uk/ or send a letter to Creative
Commons, 171 Second Street, Suite 300, San Francisco, California
94105, USA.

Jo Cook
OA Digital
http://oadigital.net
j.cook@oadigital.net
+44 (0)1524 880212

Worskhop Leicester 2010

Recommended

Recommended

More Related Content

Viewers also liked

Viewers also liked (12)

Similar to Worskhop Leicester 2010

Similar to Worskhop Leicester 2010 (20)

More from Joanne Cook

More from Joanne Cook (15)

Worskhop Leicester 2010