GIS AH Intro
A Brief Introduction
About this course
The GIS for Animal Health course has adopted and modified an existing QGIS course developed by Linfiniti Consulting CC. We have adopted their exercises using Indonesian data. We have also created a new chapter showing you how to use these skills and apply them to animal health problems using data from the new Indonesian animal health information system, iSIKHNAS.
The original manual was created using QGIS 1.8, and we have continued with this version for this manual. The original manual, which includes more advanced exercises, is available from this website and also here
Welcome to this course! We are going to show you how to use QGIS easily and efficiently. If you're new to GIS, we'll tell you what you need to get started.
If you're an experienced user, you'll see how QGIS fulfills all the functions you expect from a GIS program, and more!
A few basics about GIS
Just as we use a word processor to write documents and deal with words on a computer, we can use a GIS application to deal with spatial information on a computer. GIS stands for ‘Geographical Information System’.
A GIS consists of:
- Digital Data – the geographical information that you will view and analyse using computer hardware and software.
- Computer Hardware – computers used for storing data, displaying graphics and processing data.
- Computer Software – computer programs that run on the computer hardware and allow you to work with digital data. A software program that forms part of the GIS is called a GIS Application.
With a GIS application you can open digital maps on your computer, create new spatial information to add to a map, create printed maps customised to your needs and perform spatial analysis.
GIS is a relatively new field — it started in the 1970’s. It used to be that computerised GIS was only available to companies and universities that had expensive computer equipment. These days, anyone with a personal computer or laptop can use GIS software. Over time GIS Applications have also become easier to use –– it used to require a lot of training to use a GIS Application, but now it is much easier to get started in GIS even for amateurs and casual users. As we described above, GIS is more than just software, it refers to all aspects of managing and using digital geographical data. In the tutorials that follow we will be focusing on GIS Software.
GIS software applications are normally programs with a graphical user interface that can be manipulated using the mouse and keyboard. The application provides menus near to the top of the window (File, Edit etc.) which, when clicked using the mouse, show a panel of actions. These actions provide a way for you to tell the GIS Application what you want to do. For example you may use the menus to tell the GIS Application to add a new layer to the display output.
Layers - A common function of GIS Applications is to display map layers. Map layers are stored as files on a disk or as records in a database. Normally each map layer will represent something in the real world –– a roads layer for example will have data about the street network.
Map view - When you open a layer in the GIS Application it will appear in the map view. The map view shows a graphic representing your layer. When you add more than one layer to a map view, the layers are overlaid on top of each other. You will often see a map view that has several layers added to it. An important function of the map view is to allow you to zoom in to magnify, zoom out to see a greater area and move around (panning) in the map.
Map Legend - Another common feature of GIS Applications is the map legend. The map legend provides a list of layers that have been loaded in the GIS Application. Unlike a paper map legend, the map legend or ‘layers list’ in the GIS Application provides a way to re-order, hide, show and group layers. Changing the layer order is done by clicking on a layer in the legend, holding the mouse button down and then dragging the layer to a new position. By changing the layer order, the way that layers are drawn can be adjusted – in this case so that rivers are drawn over the roads instead of below them.
There are many different GIS Applications available. Some have many sophisticated features and cost tens of thousands of rupiah for each copy. In other cases, you can obtain a GIS Application for free. Deciding which GIS Application to use is a question of how much money you can afford and personal preference. For these tutorials, we will be using the QGIS Application. QGIS is completely free and you can copy it and share it with your friends as much as you like.
GIS data - Now that we know what a GIS is and what a GIS Application can do, let’s talk about GIS data. Data is another word for information. The information we use in a GIS normally has a geographical aspect to it. Here is the start of some example data collected by a health care worker. She created a table to record diseases that looked like this:
Longitude Latitude Disease Date 26.870436 -31.909519 Mumps 13/12/2008
The longitude and latitude columns hold geographical data. The disease and date columns hold non-geographical data.
A common feature of GIS is that they allow you to associate information (non-geographical data) with places (geographical data). In fact, the GIS Application can store many pieces of information which are associated with each place – something that paper maps are not very good at. For example, our health care worker could store the person’s age and gender on her table. When the GIS Application draws the layer, you can tell it to draw the layer based on gender, or based on disease type, and so on. So, with a GIS Application we have a way to easily change the appearance of the maps we created based on the non-geographical data associated with places.
GIS Systems work with many different types of data.
Vector data is stored as a series of X, Y coordinate pairs inside the computer’s memory. Vector data is used to represent points, lines and areas. Illustration figure_vector_data shows different types of vector data being viewed in a GIS application. In the tutorials that follow we will be exploring vector data in more detail.
Vector data is used to represent points (e.g. towns), lines (e.g. rivers) and polygons (e.g. municipal boundaries).
Raster data are stored as a grid of values. There are many satellites circling the earth and the photographs they take are a kind of raster data that can be viewed in a GIS. One important difference between raster and vector data is that if you zoom in too much on a raster image, it will start to appear ‘blocky’ (see illustrations figure_raster_data_1 and figure_raster_data_2). In fact these blocks are the individual cells of the data grid that makes up the raster image. We will be looking at raster data in greater detail in later tutorials.
Raster data are often images taken by satellites. Here we can see mountains in the Eastern Cape.
What have we learned?
Let’s wrap up what we covered in this brief overview:
- A GIS is a system of computer hardware, computer software and geographical data.
- A GIS Application allows you to view geographical data and is an important part of the GIS.
- A GIS Application normally consists of a menu bar, toolbars, a map view and a legend.
- Vector and raster data are geographical data used in a GIS application.
- Geographical data can have associated non-geographical data.
Think about these
3 reasons why GIS is more useful than paper maps.
- GIS Applications allow you to create many different types of maps from the same data.
- GIS is a great visualisation tool that can show you things about your data and how they are related in space.
- Paper maps need to be filed and are time consuming to view. The GIS can hold a very large amount of map data and make it quick and easy to find a place you are interested in.
How could raster data from satellites be useful? Here are some ideas we had:
- During natural disasters, raster data can be useful to show where the impacted areas are. For example a recent satellite image taken during a flood can help to show where people may need rescuing.
- Sometimes people do bad things to the the environment, like dumping dangerous chemicals that kill plants and animals. Using raster data from satellites can help us to monitor for these type of problems.
- Town planners can use raster data from satellites to see where informal settlements are and to help in planning infrastructure.
Trainers: Something to think about
If you don’t have a computer available, many of the topics we cover in this tutorial can be reproduced using an overhead and transparency as it uses the same technique of layering information. However, to properly understand GIS it is always better to learn it using a computer.
Book: Desktop GIS: Mapping the Planet with Open Source Tools. Author: Gary Sherman. ISBN: 9781934356067
The QGIS User Guide has more detailed information on working with QGIS.
In the modules that follow we are going to go into more detail, showing you how to use a GIS Application. All of the tutorials will be done using QGIS.
How to use this material
Any text that looks like this refers to something on the screen that you can click on.
Text that looks like this directs you through menus.
This kind of text refers to something you can type, such as a command, path, or file name.
Tiered course objectives
This course caters to different user experience levels. Depending on which category you consider yourself to be in, you can expect a different set of course outcomes. Each category contains information that is essential for the next one, so it's important to do all exercises that are at or below your level of experience.
In this category, the course assumes that you have little or no prior experience with theoretical GIS knowledge or the operation of a GIS program.
Limited theoretical background will be provided to explain the purpose of an action you will be performing in the program, but the emphasis is on learning by doing.
When you complete the course, you will have a better concept of the possibilities of GIS, and how to harness their power via QGIS.
In this category, it is assumed that you have working knowledge and experience of the everyday uses of GIS.
Following the instructions for the beginner level will provide you with familiar ground, as well as to make you aware of the cases where QGIS does things slightly differently from other software you may be used to. You will also learn how to use analysis functions in QGIS.
When you complete the course, you should be comfortable with using QGIS for all of the functions you usually need from a GIS for everyday use.
In this category, the assumption is that you are experienced with GIS, have knowledge of and experience with spatial databases, using data on a remote server, perhaps writing scripts for analysis purposes, etc.
Following the instructions for the other two levels will familiarize you with the approach that the QGIS interface follows, and will ensure that you know how to access the basic functions that you need. You will also be shown how to make use of QGIS' plugin system, database access system, and so on.
When you complete the course, you should be well-acquainted with the everyday operation of QGIS, as well as its more advanced functions.
As information becomes increasingly spatially aware, there is no shortage of tools able to fulfill some or all commonly used GIS functions. Why should anyone be using QGIS over some other GIS software package?
Here are only some of the reasons:
- It's free. Anyone can download it and use it - it costs nothing.
- It's powerful - as powerful and sophisticated as most high-level, expensive GIS software packages you buy off the shelf.
- It's open source which means you can sponsor the development of a feature, or add it yourself if you are familiar with programming. You are free to make it grow to suit your needs.
- It's constantly developing. Because anyone can add new features and improve on existing ones, QGIS never stagnates. The development of a new tool can happen as quickly as you need it to.
- Extensive help and documentation is available. If you're stuck with anything, you can turn to the extensive documentation, your fellow QGIS users, or even the developers.
- Cross-platform. QGIS can be installed on MacOS, Windows and Linux.
Now that you know why you want to use QGIS, we can show you how. The first lesson will guide you in creating your first QGIS map.
Note: Before you go to the first module make sure that you have downloaded, installed and can open QGIS v.1.8 Click here to download
Click here to go to Module 2 : The Interface
Click here to go back to the list of Modules