an introduction to quantum gis · pdf filewhat is quantum gis? •developed in 2002 and...

An Introduction to Quantum GIS

Lachlan Smeed, QUT

What is Quantum GIS?

• Developed in 2002 and undergone significant development.

• Open source, community driven geographic information system.

• Runs on Linux, Windows and/or MacOS.

• Fully functioning desktop geographic information system.

Features of QGIS• Features of QGIS include;

• Importing data from multiple sources

• Digitizing

• Editing

• On the fly reprojection

• Geoprocessing

• Database connectivity; and

• Raster processing

• Professional and easy print layout function

• QGIS is a free program

• Very user friendly

• Simplified version of expensive GIS based software

• Program negotiation is straight forward

• Help tips for new users

• Professional layout opportunities

• Works on laptops

Benefits of QGIS

Data Capture

• Queensland Spatial Portal and Queensland Government Information System

• A large free spatial database

• Thousands of datasets relating to Queensland and individual regions

• Easy to negotiate for appropriate data

• Metadata normally attached to data for ease in later analysis

Importing Data• QGIS is able to import multiple data sets, including;

• Vector and Raster

• Post GIS tables

• Databases

• MSSQL tables

• WMS and WCS server layers

• Layer creation from a deliminated text file

• Creation of new spatialite layer

Raster Data Source

• USGS Earth Explorer, a site for free raster data

• Contains Large amount of;

• Landsat Imagery

• Aerial Photography

• Heat Signature data; and

• Much more data

• Raster data require georeferencing

• USGS provide metadata showing coordinates

Plugins and Georeferencing• QGIS requires the

installment of the Georeferencer plugin

• Georeferencer is a free QGIS plugin

• Requires the coordinates of the corners of raster image

• Makes vector and shape files match up appropriatley.

• Vector data and shape files require geographic datum of Australia (GDA 94)

Filtering Features • To get selected vector layer

or shape file features filter equation required

• Filter equation much like that of a query equation in ArcGIS

• Example;

• A filter equation was used to show the only town feature named Roma

Print Composer • QGIS tool to present maps on paper

• There are three main types of map projection

• These include;

• Cache

• Rendering

• Rectangular

• Cache- Prevents movement of map, allows zooming only

• Rendering- Movement of map around like main window

• Rectangular- Displays ‘Map Printed Here’ only

Features of Print Composer

• Easy creation of professional map layouts and presentations

• Essential map features and secondary maps

• This Includes;• A scale bar

• Legend

• Title

• Orientation Features

• Ability to insert custom images, change paper size, background colour, orientation and measurement units.

• Ability to export images as JPEG, PDF and SVG file types

Example Map SeriesSurat Basin, Queensland

Benefits of QGIS

Students Professionals

• Detailed analysis of specific data

• Simplified version of other complicated GIS software

• Easy to understand• it’s free

• Detailed analysis of specific data

• It’s free• Development of more in-

depth and detailed programs

• Extended analytical opportunities

• Advanced mapping opportunities

Any Questions?