maps4finland 28.8.2012, pekka sarkola
DESCRIPTION
Pekka Sarkola (Gispo Oy): Understanding and processing geo data with QGISTRANSCRIPT
Understanding and processing geodata with Quantum GIS
Pekka Sarkola Gispo Oy
Gispo Oy We help customers to take advantage of the FOSS4G
(Free and Open Source So;ware for Geospa=al) so;ware and open data.
We support the development and u=lisa=on of open source so;ware and open data.
GIS in 5 minutes
GIS = Geographic Informa?on System
Data representa?on • Representa?on of real objects • Abstrac?on to – Discrete objects, like house – Con?nuous fields, like rainfall amount or eleva?on
• ”60-‐80% of all informa=on has loca=on” • Can only physical, real objects has loca?on? – Email – Money in bank account
Geographic informa?on data • Raster – Image
• Vector – Point – Polyline – Polygon
+ ANributes: name, id, type…
Collect
Model
Analyse Visualise
Share
What’s not GIS? • CAD – Computer-‐aided Drawning – Be aware about: DXF, DWG, …
• Google Maps – Points-‐on-‐the-‐map
Map projec?ons • Always distor?on of – Area – Shape – Direc?on – Bearing – Distance – Scale
Coordinate systems • You use already defined coordinate systems – …or do your own coordinate system
• Roughly 2000 – 3000 different coordinate systems • Web Nerd Shortcut (WNS): – ”I just use GPS coordinates”
• GIS Expert Answer (GEA): – ”So, you will use WGS84. Like La?tude / Longitude. How do you calculate distance between two points?”
Map Projec?on • WNS: ”I will use Google Web Mercator on my data visualisa?on”
• GEA: ”Right:”
Geodata File formats
Geodata File Formats • WMS: ”I will use SVG/XML/KML in my app…” • GEA: ”As you want, but…” – Size of files: XML is preNy big – Features: KML includes presenta?on – Data inside SVG?
Using Quantum GIS
Why Quantum GIS? • Some?mes you have to: – View, analyze, convert, manipulate or do something else with your geodata
• Quantum GIS is easy to use, free open source sojware for Linux, Mac and Windows plakorms
• More info and download: – hNp://www.qgis.org/
Live-‐demo
Where I can learn more? • Open Knowledge Fes?val, 17.-‐22.9.2012 – Open Geodata Hackathon and all other Open * things – www.okfes?val.org
• Paikka?etomarkkinat, 6.-‐7.11.2012 – Annual GIS event in Finland – www.paikka?etomarkkinat.fi
Or just contact me!
Ques%ons? Thank you!
Presenta?on includes maps from: © Na?onal Land Survey of Finland, data extract 05/2012
posiki