[flbazar]

you know blind people can't see but they can feel the touch in their body for example their chest
now consider a radar attached to the head and a screen attached to the chest of the blind guy that can measure the size and the distance of an object and this radar is connected to the screen that actually turns the distance of the object to the pressure .
nearer the object the more pressure it makes
the bigger the object vaster the area is under pressure!
so blind people can actually understand the size and the distance of objects