Illusion

https://www.youtube.com/watch?v=V7C318DGB38

The whole video is about an illusion which is not so obvious but probably many people have faced it at least once in their life. It is very interesting that it is only caused by the sun and shadows also it shows how accustomed we are to surrounding world. It is so that in many paintings, pictures, and even religions dark is down and light is up, this is so important that International Space Station has lights mounted on one side to make it easier for the astronauts, likewise cartographers create maps as if the sun was above them which is impossible in the real world. It shows how easy it is to twist and confuse our brains.

Convex
This polygon is convex

Concave


Dent
After the crash his car had many dents