QGIS/C2/Coordinate-Reference-Systems/English-timed

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Time Narration
00:01 Welcome to this tutorial on Coordinate Reference System in QGIS.
00:07 In this tutorial, we will learn to,
00:10 Add layers to projections in QGIS.
00:15 View metadata information for layers.
00:19 Save selected features from a layer to a new layer.
00:24 Re-project and overlay data layers of different projections together.
00:30 To record this tutorial I am using,

Ubuntu Linux OS version 16.04, QGIS version 2.18

00:42 To follow this tutorial you should have basic knowledge about GIS.
00:49 Please view previous tutorial in this series.
00:54 About Coordinate Reference Systems,
00:57 Coordinate Reference Systems are of two types,

Geographic coordinate system, and Projected Coordinate System

01:06 Most widely used geographic coordinate system is WGS 84.
01:12 Most widely used projected coordinate system is UTM.
01:18 Here I have opened QGIS interface.
01:23 On the canvas, world map with country administration boundaries is displayed.
01:30 Demonstration on how to download the map and display in QGIS is explained in the prerequisite tutorial.
01:39 Please view the pre-requisite tutorial.
01:43 This file can also be downloaded from the Code files link.
01:48 On the left-side of the canvas, you will see Layers Panel, with file name of the world map as a layer.
01:57 By default Layers Panel is enabled here.
02:02 If not, we can enable or disable the Layers Panel using View menu.
02:08 Click on View menu on the menu bar.

Scroll down and select Panels option.

02:16 Sub-menu shows a list of panel names.
02:21 Click on Layer Panel option to enable or disable the panel.
02:27 We can adjust the size of the panel by dragging the boundary.
02:32 If you wish to change the color of the map, right-click on the layer name in the Layers Panel.
02:39 Scroll-down the context menu and select Styles option.
02:44 Sub-menu shows a color triangle .
02:48 Choose the color by rotating the vertex of the color triangle.
02:53 Click anywhere on the canvas to close the context menu.
02:58 At the bottom-left corner, on the status bar of QGIS window, you will notice the label Coordinate and a text box with numbers.
03:09 Values of X and Y coordinates for a particular location are shown in this text box.
03:17 Move the cursor over the map.
03:20 Observe, that the values of X and Y coordinates change with location of the cursor.
03:28 By default Render option is checked on the status bar.

Leave it as such.

03:37 On the status bar, at the bottom-right corner, you will see another label, Current CRS
03:44 This code represents the current Projection Coordinate Reference System.
03:50 To determine a layer’s projection, we can look into the metadata.
03:56 On the Layers Panel, right-click on the layer name.
04:01 From the context menu, select Properties.

Layer Properties dialog-box opens.

04:09 In the dialog-box, on the left-side panel, click on Metadata option.
04:15 Under Properties section, scroll down the slider.
04:20 At the bottom, under heading, Layer Spatial Reference System, you will see the definition for this projection.
04:29 It shows WGS84 as geographic coordinate system.
04:35 Click on Ok button at the bottom, to close the dialog box.
04:41 Let us now add layers to the map and change the projection.
04:47 About data layers.
04:50 Usually geographical data is stored in layers in a GIS workspace.
04:57 Each layer has data stored in its attribute table.
05:02 Many layers can represent data of the same geographical location.
05:08 Back to the QGIS interface.
05:12 Now let us see how we can change the layer’s projection.
05:17 This operation is called Re-Projection.
05:21 Instead of re-projecting the entire layer, we will re-project some features.
05:27 On top-right corner of the tool bar, click on Select features by area or single click tool.
05:35 Click on the black triangle next to this tool.
05:39 From the drop down choose Select features.
05:44 On the world map displayed on canvas, click on the United States of America feature to select it.
05:52 Note that, the United States of America is shown in a different color.
05:58 We will now change the projected coordinate system of this layer and save.
06:04 Right-click on the layer name in the Layers Panel.
06:08 Scroll down, select Save As option.
06:12 Save Vector Layer as... dialog box opens.
06:17 The default format option is ESRI Shapefile.

Leave it as such.

06:26 Click on Browse button next to File name text box.
06:31 Save layer as... dialog-box opens.

Name the output layer as USA-1.shp.

06:41 Find a suitable location to save.

I will save it on Desktop

06:48 Click on Save button at the bottom.
06:52 In the Save Vector Layer as.... dialog-box, the file path appears in the File name text box.
06:59 We will choose the new projection for this layer.
07:03 Next to the CRS drop down box, click on Select CRS button.
07:10 In the Coordinate Reference System Selector, in the Filter search box, enter North America
07:17 Under Coordinate reference systems of the world, under heading Projected Coordinate System, scroll through the results.
07:27 Select, North_America_Albers_Equal_Area_Conic (EPSG:102008) projection.
07:37 Click on OK button at the bottom.
07:41 In the CRS drop down box, the newly selected CRS is shown.
07:47 Click on the check box to check Save only selected features option.
07:53 This will ensure that only the selected feature gets re-projected and exported.
08:00 Here, by default, Add saved file to map option is checked.
08:06 If not, click on the check box to check this option.
08:11 Click on OK button.
08:14 The re-projected layer gets loaded, in a different color.
08:19 These two layers are now in different projections.
08:24 Observe that, on Layers Panel, you can now see 2 entries.
08:30 Notice that the new United States layer overlays perfectly on top of the world map layer.
08:38 This is because QGIS has a feature called On-the-fly CRS transformation.
08:45 The projection text at the bottom-right corner of QGIS window has the words, OTF next to EPSG:4326.
08:56 Select the United-States layer in the Layers Panel by clicking on it.
09:02 Click on the Current CRS text, EPSG:4326, at the bottom-right corner of the status bar.
09:11 Project Properties CRS dialog-box opens.
09:16 Let us turn-off the Enable on-the-fly CRS transformation and see what happens.
09:23 Uncheck the Enable on the fly CRS transformation check box, by clicking on it.

Click on OK button at the bottom.

09:34 Back in the main QGIS window, you will see the world map disappear.
09:40 You can see only the United States map on the canvas.
09:45 This is because the Projected CRS for this layer changed to Albers Projection.
09:52 The coordinates and scale are different now.
09:56 Right-click the United States layer in the Layers Panel.
10:01 Select Zoom to Layer option.
10:05 Now you will see the United States in the selected projection.
10:10 Again, click on the Current CRS text to open Project Properties dialog-box.
10:17 Turn-on the Enable ‘on the fly’ CRS transformation option.
10:23 Under the heading Recently used Coordinate Reference Systems, select WGS 84.

At the bottom, click on OK button.

10:35 The display on the canvas will return to its previous state with world map.
10:41 To delete the vector layer from the dataset, right-click on the name in the Layers panel.
10:48 From the context menu, click on Remove option.
10:52 A prompt appears to confirm the action.

Click on OK button.

10:59 Observe that the layer is removed from the dataset.
11:04 Let us summarize,
11:07 In this tutorial we have learnt to

Add layers to projections in QGIS.

11:15 View metadata information for layers.
11:19 Save selected features from a layer to a new layer.
11:24 Re-project and overlay data layers of different projections together.
11:30 As an Assignment:

Project The United States with North_America_Lambert_Conformal_Conic projection and observe the difference.

11:43 Re-project the entire world map layer into World Mercator projection system.
11:50 Your completed assignment should look like this.
11:55 The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
12:03 The Spoken Tutorial Project team: conducts workshops and

Gives certificates on passing online tests. For more details, please write to us.

12:15 Please post your timed queries on this forum.
12:19 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

12:31 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

PoojaMoolya