2.3.1. Follow Along: 基本导航工具¶
Move your mouse to approximately the top left area of where there is the highest density of buildings and roads.
Then drag the mouse, which will create a rectangle, and cover the dense area of buildings and roads (图 2.5).
Release the left click. This will zoom in to include the area that you selected with your rectangle.
As you pan, zoom in, or zoom out, QGIS saves these views in a history. This allows you to backtrack to a previous view.
Sometimes after exploring the data, we need to reset our view to the extent of all the layers. Instead of trying to use the Zoom Out tool multiple times, QGIS provides us with a button to do that action for us.
As you zoomed in and out, notice that the Scale value in the Status Bar changes. The Scale value represents the Map Scale. In general, the number to the right of : represents how many times smaller the object you are seeing in the Map Canvas is to the actual object in the real world.
You can also use this field to set the Map Scale manually.
In the Status Bar, click on the Scale textfield.
50000and press Enter. This will redraw the features in the Map Canvas to reflect the scale you typed in.
Alternatively, click on the options arrow of the Scale field to see the preset map scales.
Select 1:5000. This will also update the map scale in the Map Canvas.
Now you know the basics of navigating the Map Canvas. Check out the User Manual on Zooming and Panning to learn about alternative ways of navigating the Map Canvas.
2.3.2. In Conclusion¶
Knowing how to navigate the Map Canvas is important, as it allows one to explore and visually inspect the layers. This could be done for initial data exploration, or to validate output of a spatial analysis.