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.mapmapserver.htmlbaselayers.htmlleicester_2010_notes.pdf

Installing Quantum GIS plugins

Needed Plugins: Mapserver Export, PostGIS manager, SPIT

Databases

Databases

● Server-based database (not like access)● Data is entirely separate from user interface● Inside the database, data stored in schemas

for finer control

+

www.postgresql.orgpostgis.refractions.net

http://www.postgresql.org/

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 pgadmin3and 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

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

● 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;

Map Servers

Types of Map Server

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

● 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/leics2010/demo.map -o /home/user/demo.png

● With a browserhttp://localhost.com/cgi-bin/mapserv?map=/home/user/leics2010/demo.map&mode=map

Adding new layers to a mapfileLAYER 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

ENDEND

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

Web Mapping: Practicalities

● Make the web folder writeablesudo chown -R user /var/wwwsudo 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

<?phpphpinfo();

?>● CLIENT-SIDE:

javascript

Solving Problems using Firefox

OpenLayers

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 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/

http://mapguide.osgeo.org/

http://mapfish.org/

http://mapchat.ca/

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.

Have fun!!!

Worskhop Leicester 2010

Documents