1. Start from the river. It provides the network in which buildings and trees can be found.
2. Draw a line from a river’s source. Other rivers will meet along the way.
3. A wider tributary takes up more than 3.5 metres. Draw a line that splits into three.
4. Consistency is key. Logic determines observation. River borders, here, have the same height.
5. Wear this pair of glasses. Sometimes, they show you how these borders escape your line.
6. Return to the river again. Because it always escapes.
7. It is only visual.