worskhop osgis2010
DESCRIPTION
Databases and web mapping the open source wayTRANSCRIPT
Databases and Web Mapping the Open Source WayOSGIS 2010: Centre for Geospatial Sciences, NottinghamJune 2010
Jo CookOA Digital
[email protected] 880212
Beyond Google Maps and Mashups
Practicalities
● Download: www.archaeogeek.com/downloads/osgis2010.zip●Save to /home/user and extract●The folder /home/user/osgis2010 contain:shape_files (folder)demo.mapmapserver.htmlbaselayers.htmlosgis_2010_notes.pdf (same as handout)
Introduction
Introduction
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Databases
● Server-based database (not like access)● Enterprise-level, with support for
transactions and multiple users
+
www.postgresql.orgpostgis.refractions.net
Ways to connect
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)
name and location of shapefile, name of table in database, coordinate system of data
Installing Quantum GIS plugins
Loading data with SPIT
Create new database with pgadmin3and connect to it with SPIT in QGIS
SPIT (continued)
Change to 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
indexCREATE INDEX yourtable_idx ON yourtable USING GIST(geometry_column);
Querying data
● SQL: Structured Query LanguageSELECT some comma de-limited columns FROM your_table WHERE some condition is met;
● Use PSQL from command line, PgAdmin3, or PostgreSQL Manager/SQL Editor
● There is no escape from typing out your query!
Spatial Querying
● Find out which county a point is in and show it on the map:
CREATE VIEW whichcounty AS SELECT “PROV3NAME” FROM united_kingdom_counties WHERE st_within(geomfromtext('point(-1.4 52.6)', 4326), the_geom);
Map Servers
Types of Map Server
● Minnesota Map Server (aka Mapserver)cgi program on a web server.
Configuration via text files● Geoserver
java-based program. Configuration via web interface
The Map FileMAP 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 ENDEND
Checking and Viewing a map file
● SHP2IMG at the command lineshp2img -m /home/user/osgis2010/demo.map -o /home/user/demo.png
● With a browserhttp://localhost.com/cgi-bin/mapserv?map=/home/user/osgis2010/demo.map&mode=map
Adding new layers to a mapfile
LAYER NAME "your layer" STATUS DEFAULT TYPE POLYGON DATA "yourshapefile.shp" (relative to the “data” parameter in your mapfile) CLASS
NAME "your name for this symbology"OUTLINECOLOR 60 60 60COLOR 255 255 0SYMBOL 0
ENDEND
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/osgis2010/demo.map&layer=layer1
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
Web Servers and Web Pages
Structure of a web page
<html>
<head><title> My Home Page
</title></head>
<body>HELLO WORLD!
</body>
</html>
Scripting
● SERVER-SIDE:php, asp
<?phpphpinfo();
?>● CLIENT-SIDE:
javascript
Solving Problems using Firefox
Solving Problems using the mailing lists
RTFM j00 n00b!!!• Get latest version of software• Read the manual/help documentation• Search the mailing list archives• Strip as much detail out of your code as possible• Provide as much information as you can about your setup and the steps you have already taken
And finally...Web Mapping
OpenLayers page structure<html>
<head><script
src="http://www.openlayers.org/api/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 directivemap.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...
Jo CookOA Digitalhttp://[email protected]+44 (0)1524 880212
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.
Open Source Web Mapping is Great Fun!!!