مادة تدريبية: تجهيز بيانات من خرائط ورقية

Finally we are going to create a polygon vector layer for some lakes. Try to find out how to do this for yourself. It is very similar to the procedure for lines. The only difference is that the first node should be the same as the last node in order to close the polygon. Use the name of the lake as a text attribute.

Some lakes have islands that need to be removed from the lake features. For this purpose, enable the Advanced Digitizing Toolbar in a similar way as we enabled the Snapping Toolbar earlier. Click the Add ring button and digitize the island in the same way as you digitize a polygon. After finalizing the ring, it will be removed from the lake polygon.

The order of the layers is also important. The order of visualization in the map canvas follows the order in the Layers panel. The first layer is on top. The general order of layers is: points, lines, polygons, rasters. Vectors below rasters are not visible, unless you use blending or opacity. This however changes the colors and should only be used if it has a purpose. You can deviate from the general order if that makes the visualization clearer. You can change the order of layers by dragging the layers in the Layers panel to the desired position.

Watch this video to check how to digitize polygons: