Difference between revisions of "QGIS/C2/Digitizing-Map-Data/English"

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|| To record this tutorial I am using-
 
|| To record this tutorial I am using-
  
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*'''Ubuntu Linux OS '''version''' '''16.04
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'''Ubuntu Linux OS '''version''' '''16.04
  
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*'''QGIS''' version 2.18
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'''QGIS''' version 2.18
  
 
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|| '''Digitizing''' is the process by which,
 
|| '''Digitizing''' is the process by which,
  
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*coordinates from a map, image or other sources of data  
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coordinates from a map, image or other sources of data  
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*are converted into a digital format.
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are converted into a digital format.
  
  
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||  
 
||  
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*To practise this tutorial, you need to download the thematic map of '''Bangalore''' city  
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To practise this tutorial, you need to download the thematic map of '''Bangalore''' city given in the '''Code files''' link.
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*given in the '''Code files''' link.
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From the context menu select QGIS Desktop.
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From the context menu select '''QGIS''' Desktop.
 
||Right-click on '''Bangalore.jpg '''file.
 
||Right-click on '''Bangalore.jpg '''file.
  
  
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From the context menu select, '''Open with, QGIS Desktop'''.
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From the context menu select, '''Open with QGIS Desktop'''.
  
 
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|-
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|| Cursor on QGIS interface.
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|| Cursor on '''QGIS''' interface.
  
  
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|| Click on '''Layer '''menu on the menu bar and select '''Create Layer''' option.
 
|| Click on '''Layer '''menu on the menu bar and select '''Create Layer''' option.
  
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From the sub-menu, click on '''New Shapefile Layer''' option.
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From the sub-menu, select '''New Shapefile Layer''' option.
  
 
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|| Point to '''CRS'''
 
|| Point to '''CRS'''
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|| In the '''CRS''', let the '''CRS '''be '''WGS 84.'''
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|| Let the '''CRS '''be '''WGS 84.'''
  
 
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|| Point towards the created features.
 
|| Point towards the created features.
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|| In the '''Point1: Features''' dialog-box, in '''id''' column, two points are created.
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|| In the '''Point-1: Features''' dialog-box, in '''id''' column, two points are created.
  
 
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|| In''' New field Name '''type '''area.'''
 
|| In''' New field Name '''type '''area.'''
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|| In the ''' New field Name '''text box''', '''type '''area.'''
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|| In''' New field Name '''text box''', '''type '''area.'''
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|| Type the File name as A'''rea-1 '''in
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|| Type the File name as '''Area-1 '''in
  
  
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|| In '''Area-1- Feature Attributes''' input box,
 
|| In '''Area-1- Feature Attributes''' input box,
  
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Type '''1''' in ID text box.
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Type 1 in ID text box.
  
  
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Type '''1''' in the'''id''' text box.
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Type 1 in the '''id''' text box.
  
  
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|| Click on x on the top-left corner of the '''attribute table'''.
 
|| Click on x on the top-left corner of the '''attribute table'''.
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|| We can see that 2 features have been created with columns '''id''' and '''Area''' type.
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|| We can see that 2 features have been created with columns '''id''' and '''area''' type.
  
  

Latest revision as of 17:27, 23 October 2018

Visual Cue Narration
Slide Number 1

Title Slide

Welcome to this tutorial on Digitizing Map Data in QGIS.
Slide Number 2

Learning Objectives

In this tutorial, we will learn to-
  • Create and digitize Point and Polygon shape files.
  • Change style and color for Point and Polygon features.
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

To follow this tutorial, you should be familiar with basic GIS and QGIS interface.
Slide Number 5

Digitizing


Digitizing is the process by which,

coordinates from a map, image or other sources of data are converted into a digital format.


The converted data can be stored as a point, line or a polygon feature in GIS.

Slide Number 6

Example map to practise


To practise this tutorial, you need to download the thematic map of Bangalore city given in the Code files link.


This is a map depicting development of Bangalore city.

Slide Number 7

Steps to download Code files

Steps to download the code files.


Click on the link Code files, located below the player and save it in your folder.


Extract the downloaded zip file.


Locate Bangalore.jpg file in the extracted folder.

Show the map Bangalore.jpg on desktop. I have already downloaded the Code file, extracted and saved in a folder on Desktop.
Double-click on the folder. Double-click on the folder to open it.
Right-click on Bangalore.jpg file.


From the context menu select QGIS Desktop.

Right-click on Bangalore.jpg file.


From the context menu select, Open with QGIS Desktop.

Cursor on QGIS interface.


In QGIS tips dialog-box, click on OK button.

QGIS interface opens.


QGIS Tips dialog-box opens.


Click on OK button.

Cursor on Coordinate Reference System Selector dialog-box Coordinate Reference System Selector dialog-box opens.
Click on WGS 84, under the heading, Coordinate reference systems of the world.


Click on OK button.

Under the heading, Coordinate reference systems of the world, Select WGS 84.


Note that WGS 84 is the most widely used geographic coordinate system.


Click on OK button at the bottom of the dialog-box.

Cursor on canvas. Thematic map of Bangalore is displayed on the canvas.
Now let us create new shape file layers.
Click on Layer menu.

Select Create Layer option.

Click on New Shapefile Layer option.

Click on Layer menu on the menu bar and select Create Layer option.

From the sub-menu, select New Shapefile Layer option.

Cursor on New Shapefile Layer dialog box. New Shapefile Layer window opens.
Point to the 3 options Here you can see options for 3 types of features, Point, Line and Polygon.
Point to Point option By default Point option is selected.


Leave it as such.

Point to CRS Let the CRS be WGS 84.
Click on OK button. Click on OK button at the bottom-right corner of the window.
Type Point-1 in the name field in Save Layer as.. dialog-box .


Save Layer as.. dialog-box opens.


Let us name the file as Point-1.

Select Desktop.


Click on Save button.

Select a suitable location to save the file.

I will choose Desktop.


Click on Save button at the bottom-right corner of the dialog-box.

Show the desktop which has all the saved files. Files will be saved on the desktop as shown here.
Point towards the Point-1 layer on Layers panel. Back to the QGIS interface.


Notice that the file will be automatically loaded in the Layers Panel.

Cursor on the map. On this map, we will mark the locations where IT departments are established.
Scroll the centre mouse button. Scroll the center mouse button to zoom-in.
Cursor on the points.


Cursor on the legend.

Refer to the legend at the bottom-right corner of the map for IT establishments.


IT establishments are indicated as flag symbol.

Locate the points indicating IT establishments on the map.

Click on the symbols for IT establishments as indicated on legend. There are two points indicating IT establishments.
To edit or modify features on the map, we need to select the Toggle editing tool.
Point to the Toggle Editing. Toggle Editing tool is available on the top-left corner of the tool bar.
Click on the Toggle Editing tool on tool bar. Click on the Toggle Editing tool to select it.
Select Add Feature option. Click on Add Feature tool on the tool bar.
High-light the cursor (editing) The cursor is now displayed as a crosshair icon.
Click on flag symbol. Click on IT establishment symbol on the map.
Type I in the text box in Point-1 Feature Attribute input box.


Click on OK button.

An input-box Point-1 Feature Attributes opens.


Type 1 in the id text box.


Click on OK button.

Click on another symbol for IT establishment.


Type 2 in the text box in Point-1 Feature Attribute input box


Click on OK button.

Similarly click on the second IT establishment and save the feature as 2.



Click on OK button.

Click on Toggle Editing tool on the tool bar. Now to stop editing, again click on Toggle Editing tool on the tool bar.
click on Save button in Stop editing dialog-box. Stop editing dialog-box opens.

Click on Save button.

Point towards two colored dots on the map. Observe, on the map, two colored point features are created.
We can check the two features created, by opening the attribute table.
Right-click on the Point-1 layer on the Layers panel.


From the context menu, select Open Attribute Table option.

Right-click on the Point-1 layer on the Layers panel.


From the context menu, select Open Attribute Table option.

Point towards the created features. In the Point-1: Features dialog-box, in id column, two points are created.
Click on x symbol at the top-left corner of the attribute table. Close the attribute table dialog-box.
Cursor on the canvas. Style and color of these point features can be changed for clear visibility.
Right-click on Point-1 layer. Right-click on the Point-1 layer.
From the context menu choose Properties option. From the context menu choose Properties option.
Cursor on Layer Properties dialog-box. Layer Properties dialog-box opens.
Click on the Color drop down.


Rotate color triangle.

Click on the Color drop down.


Choose a color by rotating the color triangle.

Click the upward arrow triangle at the end of the Size text box. Increase the size by clicking on upward arrow triangle at the end of Size text box.
Click on OK button at the bottom of the window. Click on OK button at the bottom of the dialog-box.
Cursor on Point features. Notice the change in color and size for the Point features.
Now let us create a shape file containing Polygon features.
Click on Layer menu on the menu bar.

Select Create Layer option.

Click on Layer menu on the menu bar.


Select Create Layer option.

Click on New Shapefile Layer option. From the sub-menu, select New Shapefile Layer.
In the New Shapefile Layer dialog box,

Click on Polygon radio button

New Shape File Layer window opens.


Select Type as Polygon.

In New field Name type area. In the New field Name text box, type area.


Let the Type be Text data.

Click on Add to fields list button.


Point to the two rows in Fields List table.

Click on OK button.

Click on Add to fields list button


In the Fields List table, you will see area row added.


Click on OK button.

Type the File name as Area-1 in


Save Layer as.. dialog-box.

Save layer as.. dialog-box opens.


Type the File name as Area-1.

Select Desktop.


Click on Save button

Select a suitable location.


I will select Desktop.


Click on Save button.

Point to the Layer Panel and

Area-1 layer.

Notice that Area-1 layer is added to the Layers panel.
We will mark the boundary of Corporation Area and Greater Bangalore area.
Point to the Legend on the map. Refer to the Legend on the map to locate Corporation area and Greater Bangalore area.
Click on Toggle Editing tool on the tool bar. Turn on the toggle editing by clicking on Toggle Editing tool on the tool bar.
Click on Add Feature tool from the tool bar. (The tool is 4th tool from left on the 2nd row on tool bar)


Click on Add Feature tool from the tool bar.
Bring the cursor to the map.


Right click to end the polygon.

Bring the cursor to the map.


To mark the area, click anywhere on the boundary of Corporation area.

Click on the boundary of corporation area. Keep clicking on the boundary.
Point to the warning messages. Warning messages may appear at the top of the canvas if the line segments intersect.


Please ignore these messages.

Press Esc Key on the keyboard. If you make a mistake and want to restart the marking process, press Esc Key on the keyboard.


You can start the process again.

Click on the entire boundary. Keep clicking on the boundary till you span the entire boundary.
Right click to end the polygon. Once you have marked the entire boundary, right-click to end the polygon.
In Area-1- Feature Attributes input box,

Type 1 in ID text box.


and City Corporation Area in Area text box.

Area-1- Feature Attributes input box opens.


Type 1 in the id text box.


Type Corporation Area in area text box.

Click on OK button. Click on OK button.
Point to the polygon feature. Observe, on the map new polygon feature is created.
Now we will digitize Greater Bangalore region in the map.
Click on the boundary of Greater Bangalore region. Click on the boundary to digitize Greater Bangalore region as shown here.
Right-click to end the polygon. After you finish digitizing, right-click to end the polygon.
In the Area-1 Feature Attributes text box,

Type 2 in the id text box.

Type Greater Bangalore in the area text box.

In the Area-1 Feature Attributes text box, type 2 in the id text box.


And Greater Bangalore in the area text box.

Click on OK button. Click on OK button.
Click on Toggle Editing tool in the tool bar. Again click on Toggle Editing tool in the tool bar to stop editing.
Click on Save button in the Stop editing dialog box. Click on Save button in the Stop editing dialog box.
Right click on Area-1 layer in the layers panel.


Open attribute table from the context menu.

Right click on Area-1 layer to open attribute table.


Select Open Attribute Table from the context menu.

Click on x on the top-left corner of the attribute table. We can see that 2 features have been created with columns id and area type.


Close the attribute table.

Point to polygon features on the map. We can see that two polygon features have been created.
Right click Area-1


Select Properties option from context menu.

To change the color and style of polygon feature, right click on Area-1 layer.

Select Properties option.

In the Layer Properties dialog-box, click on style option. In the Layer Properties dialog-box, select Style option from the left panel.
Select categorized option from top left corner of the drop down menu. On the top left corner of the drop down menu, select categorized.
In the column drop down select id.


Click on Classify button.

In the column drop down select id.


Click on Classify button.

Drag the transparency slider to 50 %. Move the Layer transparency slider to 50 %.
Click Ok button. Click on OK button at the bottom of the dialog-box.
Point to two polygon features on the map. Now on the map, we can see that the two Polygon features are in different color.
Details about labeling the features, will be discussed in upcoming tutorials in the series.
Let's summarize.
Slide Number 8

Summary

In this tutorial we have learnt to,
  • Create and digitize Point and Polygon shape files.
  • Change style and color for Point and Polygon features.
Slide Number 9

Assignment

As an Assignment,

On the Banglaore thematic map (Bangalore.jpg),

  • Digitize Industrial Estates
  • Digitize the roads on the map, by creating a Polyline feature.
Your completed assignment should look as shown here.
Slide Number 10

About the Spoken Tutorial Project

The video at the following link summarises the spoken tutorial project.

Please download and watch it.

Slide Number 11

Spoken Tutorial Workshops

The spoken tutorial project team conducts workshops and gives certificates on passing online tests

For more details please write to us.

Slide number 12

Forum for specific questions:

Please post your timed queries on this forum.
Slide number 13

Acknowledgements

The Spoken Tutorial Project is funded by NMEICT, MHRD Government of India.


More information on this mission is available at the following link.

Slide number 13

Acknowledgements

This tutorial is contributed by Prajwal.M from Sahyadri college of Engineering and Snehalatha from IIT Bombay.

Thank you for joining.

Contributors and Content Editors

Nancyvarkey, Snehalathak

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