There are many complaints that AI sees through walls, bushes, hills but this is not the case.
What really happens is that they seem to know target's exact position at all times and this has nothing to do with vision.
This video shows the issue as well as including a short analysis of it:
http://youtu.be/_voCqNMc0TA {F19371} {F19372} {F19373} {F19374}