(6.3.3) The viewpoint of others is important
In order to refine the idea, the viewpoint of others is important. For example, when you look at a sphere from a certain point of view, more than half of the sphere is not visible.
When the visible range is a smooth spherical surface, it tends to be assumed that the unseen place is also a smooth sphere. But it may be sharp and holes may be open. It is impossible to observe from your point of view.
https://gyazo.com/79862332dbcfe94c5b87cac2d5363fb4
Misunderstanding if judging from a limited view
The more you succeed at the current point of view, the easier it is to forget about things that you do not see. In order not to overlook the back side of the sphere, it is important to observe from different perspectives. Even when you see things by yourself, it is important to strive to see from multiple perspectives, but it is not easy. You can achieve it more easily by borrowing the eyes of others.
https://gyazo.com/63853172e173dfa8aa61b6620a11b815
Reduce blind spots by observing from multiple viewpoints