How to extract zones that are contained in bigger zones from two different layers

How do I isolate an area in Qgis?

Quote from video: Features button and click it and go to select features by area or a single click click there and now you can select the area you want when it gets selected uh it will appear in yellow.

How do I subtract one layer from another in Qgis?

How can I do this? If both polygons are separate features, you can delete the small one via the Attribute Table (right-click the layer), toggle the Editing icon (looks like a pencil), select the feature of the polygon you wanted deleted, then select Delete Feature. Thank you.
 

How do I compare two shapefiles in Qgis?

1 Answer

1. Loop through the first feature collection.
2. Find any geometries in the second collection that intersect with the current feature.
3. Union those together (if there are more than one) and subtract (difference) that union from the first feature.
4. Save the results.