QGIS/C2/Vector-Data-Styling/English
Visual Cue | Narration |
Slide Number 1
Title Slide |
Welcome to this tutorial on Vector Data Styling in QGIS. |
Slide Number 2
Learning Objectives |
In this tutorial we will learn to,
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Slide Number 3
System Requirement |
To record this tutorial I am using,
Ubuntu Linux OS version 16.04. QGIS version 2.18. |
Slide Number 4
Pre-requisites www.spoken-tutorial.org. |
To follow this tutorial you should be familiar with QGIS interface.
If not, For relevant tutorials, visit our website. |
Slide Number 5
Example map to practise |
To practise this tutorial,
you need to download the folder given in the code-files link, located below the player. Extract the contents of the downloaded zip file. Locate world.shp file in the extracted folder. |
Show the map on desktop. | I have already downloaded the code file, extracted and saved in a folder on desktop. |
Double-click on code-files folder.
Right-click on world.shp file. From the context menu select Open with, QGIS Desktop. |
Double-click on the code-file folder to open it.
Right-click on world.shp file. From the context menu, select Open with QGIS Desktop option. |
Cursor on the QGIS interface.
Cursor on QGIS tips dialog-box.
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QGIS interface opens.
QGIS tips dialog-box opens. Click on OK button to close the dialog-box. |
Cursor on the map. | World map with Country boundaries loads on the canvas in the default style. |
Point to the world layer in the Layers panel. | You can see the world layer in the Layers Panel. |
Right-click on the layer name in the layer panel.
Select attribute table from the context menu. |
Right-click on the world layer.
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Cursor on attribute table. | Attribute table for this layer opens. |
Point to columns.
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Here we can see all the data of various features embedded in row and column format.
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Drag the slider at bottom of the table towards right. | Drag the slider at bottom of the table and navigate to POP_EST column. |
Navigate to POP_EST column.
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Notice the population column, POP_EST.
In this column population for various countries is listed. |
Cursor on the POP_EST column. | Next, we will depict the population data shown here, in various styles on the world map. |
Click on the red x mark on the top-left corner. | Close the attribute table. |
Right click the layer in the layer panel.
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Right click on the world layer.
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Cursor on the window. | Layer Properties dialog-box opens. |
Click on Style tab from the left panel. | Click on Style tab from the left panel.
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Click on drop down button. | Click on the drop-down button located on the top left corner of the dialog-box. |
Point towards the various options | You will see various styling options here.
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Select Single Symbol option. | Select Single Symbol option.
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Click on add Symbol layer button (+ button) under Fillpanel. | Click on add Symbol layer button available under Fillpanel. |
Point to options. | Various style options appear below Symbol layer type. |
Cursor on the dialog-box. | Since this is a polygon dataset, we have two basic choices. |
Cursor on the dialog-box. | You can fill the polygon with the color and fill style of your choice. |
Cursor on the dialog-box. | Outline color, style and width can also be changed. |
Click on the drop-down arrow next to Fill drop-down.
Rotate the color triangle. Choose blue color. |
Click on the drop-down arrow next to Fill drop-down.
I will choose blue color.
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Click on the drop-down arrow next to Outline text box.
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Similarly, Select Outline color.
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Click on the drop-down arrow next to Fill Style text box.
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Fill style as Dense1. |
Click on the drop-down arrow next to Outline style text box.
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Outline style, solid line. |
Click on the drop-down arrow next to Outline width text box. | Outline width, 0.46 millimeters. |
Various other style options are available to explore. | |
Click on OK button. | After you have completed the styling,
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Point to the map on the canvas. | On the canvas,
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Cursor on the canvas. | Now we will see how to map the population data. |
Cursor on the canvas. | The Single Symbol style is not very useful in mapping the population data. |
Right click on world layer,
Select Properties option. |
Let us explore another styling option.
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In the Layers Properties dialog-box, choose Categorized from the Style tab. | In the Layers Properties dialog-box,
this time we will choose Categorized from the Style tab. |
Cursor on Layers Properties dialog-box. | Categorized means, the features in the layer will be shown in different shades of a color.
These color shades are based on the unique values in the attribute fields.
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In the Column drop down, select POP_EST value. | Since we are trying to map population data, in the Column drop down we will select POP_EST. |
Select a colour ramp. | Choose a colour ramp of your choice from the drop-down.
I will choose Blues. |
Click on Classify button at the bottom of the middle panel. | Click on Classify button at the bottom of the middle panel.
The panel in the middle shows various classes with corresponding values. |
Click on OK button. | Click on OK button at the bottom right corner. |
Cursor on the map. | On the world map, you will see different countries appearing in shades of blue.
Scroll down the central mouse button to zoom-in and zoom-out the map. Lighter shades represent lower population. Darker shades represent higher population. |
Right click on world layer.
Click Properties option. |
Once again open Layers Properties dialog-box.
In Style tab, click on drop drown button. |
Click on the drop-down button.
Click on Graduated option. |
Let us explore the Graduated symbology.
Select Graduated option. |
Cursor on the dialog-box. | Graduated symbology type allows you to break down the data in a column in unique classes.
We can choose a different style for each of the classes. |
Select POP_EST | From the Column drop-down, select POP_EST. |
Click on the black triangle next to Classes text box. | We can think of classifying our population data into 3 classes, Low, Medium and High.
So, under Classes drop-down, select 3. |
Point to the panel. | You will see that 3 classes show up in the panel with corresponding values. |
Click on Classify button. | Click on Classify button. |
Click on Mode drop-down.
Point towards the modes. Select Quantile option. |
Click on Mode drop-down.
There are many Mode options available here. To keep things simple, let us use the Quantile mode. |
Point towards the modes. | These modes use different statistical algorithms to break down the data into separate classes. |
Cursor on the screen. | Also note that for an attribute to be used in Graduated style, it must be numeric field. |
Cursor on screen. | Numerical values can be Integer or Real values.
Attribute field with String type cannot be used with this styling option. |
Click on OK button. | Click on OK button. |
Point to the map. | Now on the map you will see countries in 3 different shades of blue.
These color shades represents the population data for the country. |
Point to Layers Panel. | On the Layers Panel you will see 3 classes for this layer. |
Cursor on the map. | There are some more styling options available.
We can choose a different style and color for each of these classes. |
Right click on world layer.
Click Properties option. |
Open Layer Properties dialog-box again. |
Double-click on the colored box under Symbol under Classes tab. | In Classes tab, under Symbol column , double-click on the colored box. |
Cursor on Symbol Selector dialog-box. | Symbol Selector dialog-box opens. |
In the Color drop-down option, click on the drop-down arrow.
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In the Color drop-down option, click on the drop-down arrow.
Color triangle opens. |
Rotate the color triangle and select red color. | Rotate the color triangle to choose the required color.
I will choose red color to indicate low population. |
Click on OK button at the bottom of Symbol selector dialog-box. | Click on OK button in the Symbol selector dialog-box. |
Double-click on the colored box under Symbol under Classes tab.
In the Color drop-down option, click on the drop-down arrow. Rotate the color triangle and select the color. |
Similarly change the color for other two classes.
I will choose yellow for the medium and green for high. |
Double-click on the first row in Legend column.
Type low for the first row. |
Double-click on the first row in the Legend column.
Type low for the first row. |
Double-click on the second row in the Legend column.
Type Medium for the second row. |
Type Medium for the second row. |
Double-click on the third row in the Legend column.
Type High for the third row. |
And High for the third row. |
Double-click on the first row in the Value column. | Double-click on the first row in the Value column to edit the selected ranges. |
Cursor on the Enter class bounds text box.
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Enter class bounds text box opens.
If you wish, you may edit lower value and upper value. For now we will leave the values unchanged. Click on OK button. |
Click on OK button in the Layer Properties dialog box. | Click on OK button in the Layer Properties dialog box. |
Point to world map. | Observe the world map.
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Point to Layers Panel.
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Observe the Layers Panel.
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Cursor on the map. | This style conveys a lot more useful map than the previous two attempts. |
Cursor on the map. | Let us learn how to label different features in a vector file.
For demonstration let us label the names of the countries. |
Right click on world
Click properties |
Open Layer Properties dialog box again.
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Select Show labels for this layer in the first text box drop-down. | In the first text box drop-down, select Show labels for this layer. |
Select ADMIN in Label with drop down. | ADMIN column in the attribute table has list of the names of the countries.
So in the Label with drop down, select ADMIN. |
Select Buffer.
Check the check box for Draw text buffer. |
In the style menu, Select Buffer.
Check the Draw text buffer check box. |
Click on Size drop-down.
Click on Color drop-down. |
Size of the text can be changed according to requirement.
Select a color from the color drop-down. |
Click on OK button. | Click on OK button. |
Cursor on the map. | On the world-map we can see the names of countries displayed. |
Slide Number 6
Summary |
Let us summarize,
In this tutorial we have learnt to
Single symbol styling Categorized styling Graduated styling, and
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Slide Number 7
Assignment |
As an assignment,
Categorise the data set POP_EST into 5 classes. Use Graduated styling method, Equal Interval mode. |
Point to the Assignments shown on screen. | Your completed assignment should look as shown here. |
Slide Number 8
About the Spoken Tutorial Project |
* The video at the following link summarises the spoken tutorial project.
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Slide Number 9
Spoken Tutorial Workshops |
* The spoken tutorial project team conducts workshops and gives certificates on passing online tests
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Slide number 10
Forum for specific questions:
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Please post your timed queries on this forum. |
Slide number 11
Acknowledgements |
The Spoken Tutorial Project is funded by NMEICT, MHRD Government of India.
More information on this mission is available at the following link. |
This is contributed by Prajwal.M from NIT Surathkal and Snehalatha from IIT Bombay.
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