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

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.
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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