Practical Manual - Malareo

More documents

Recommendations

Info

is highlighted, then right click on the layer name. This brings up a context menu, select remove from the menu. This removes the layer from the project. If you were to save the project it would not include the raster_cases layer. This is therefore different from turning a layer in the legend off. All layers can be turned on or off at once using “Hide all layers”. They can also be turned back on by selecting “Show all layers”. Visibility As mentioned above layers can be made visible or turned off using the tick box next to the name of the layer in the map legend. (You have done this already in a previous exercise) There are however other ways of changing the visibility of a layer. The way that layers are displayed is dependent on the properties of the layer. Exercise 5 To view the Malaria cases layer properties right click on the layer and select properties from the context menu. This opens up a Layer properties window. There are a number of Tabs at the top of the page. The far left tab is the Style page. Select the style page tab if not already active by left clicking on the tab. Directly under the Style tab is a drop down which is currently set to Graduated. Left click on the small inverted triangle next to Graduated. A drop down appears with a series of options including Single symbol, Categorized and Graduated appear. Select Single Symbol. Now click Apply at the bottom right of the layer properties window and finally click Ok. Notice that the Malaria cases layer is now a single colour with solid black lines representing the country borders in your Map View. By modifying the style of a layer you can change how a layer is represented on the map view. Notice also that when you changed the style to single symbol the options within the style tab also changed. Notice next to the Unit Color is the word Transparency 0%. To the right of this is a slider. Drag the slider to 30% by left clicking and holding down the left mouse button and dragging the slider to the right. Notice the colour becomes less and less visible. Once at QGIS for Malaria Page 10
30% release it and click on Apply and Ok. Notice you can now see the raster layer which is a satellite image of Africa through the Malaria Layer as it is now partially transparent. Saving Layers When working with GIS data it is advisable never to work on your original data. The reasons are, if the software crashes or the user makes a mistake by deleting features or data the original unaltered data is still available from to start with again. It is also worthwhile saving in progress files if modifying or editing data. It is advisable to save copies atleast each day if not every few hours. In the following exercise you will make a selection of data and save that as a new layer. Exercise 6 saving a selection Open the Project called Selection. In order to save a selection you first need to make a selection. The easiest way to do this is to select by polygon. Find the tool on the toolbar or in the view menu that says “select features by rectangle” Hold down the left mouse button and drag a rectangle over the Southern African countries. You will notice they become highlighted in yellow. Right click on the Malaria Africa_2008 layer and select the “Save Selection as”. Choose your directory and call the output Southern Africa. You have now created a new layer of just the Southern African Countries. Add this layer to the Map legend to view the layer. Moving Layers Linked to visibility is how layers are viewed relative to one another. By selecting a layer in the Map legend, holding down the left mouse button and dragging, layers can be moved relative to one another. Take the Southern African layer and drag it to underneath the Malaria layer. Notice it disappears even though it is still in the map legend. It is worth checking the order of layers in the map legend if data is no longer visible. GIS data: Layer Types: Vector Data There are 3 Main Types of Vector data. These are point line and polygon. Line using Point nodes with Co-ordinates (X,Y) (Source: University of Washington ERM250) QGIS for Malaria Page 11
Page 1 and 2: Introduction to Geographic Informat
Page 3 and 4: occurrences you can gain a better u
Page 5 and 6: Once in the folder, using your mous
Page 7 and 8: Map Legend You now have 2 layers lo
Page 9: Select the Identify features tool a
Page 13 and 14: It is important to note that althou
Page 15 and 16: Open your Identify features and exa
Page 17 and 18: Acquiring Spatial Data There are nu
Page 19 and 20: This adds the shapefile to the lege
Page 21 and 22: You will be creating a layer using
Page 23 and 24: This opens a co-ordinate reference
Page 25 and 26: Next you will create a line layer (
Page 27 and 28: Continue digitising the other roads
Page 29 and 30: If you are interested in seeing the
Page 31 and 32: PROJECT COORDINATE REFERENCE SYSTEM
Page 33 and 34: Task 1: Changing the Default CRS in
Page 35 and 36: Practical 5 Tabular Data Queries Ou
Page 37 and 38: ecords. Switching and clearing yo
Page 39 and 40: Practical 6 Spatial Analysis Outlin
Page 41 and 42: Task 1: Open a new QGIS project. A
Page 43 and 44: In order to make measurements in un
Page 45 and 46: Now to measure along the length of
Page 47 and 48: Buffer and Dissolve Buffer: Often i
Page 49 and 50: Open the Attribute Table for the Pr
Page 51 and 52: The result window shows the number
Page 53 and 54: Task 5: Slope Analysis Open a new
Page 55 and 56: Active Layers in the TOC Mathematic
Page 57 and 58: In this practical you will undertak
Page 59 and 60: 1999 (which was year 1 of the 10 ye
Page 61 and 62:
updated with percentages of prevale
Page 63 and 64:
Click on Set to current extent Leav
Page 65 and 66:
Practical 8 Summary Practical Outli
show all

Practical Manual - Malareo

Create successful ePaper yourself

Delete template?

Save as template?