A group from Northwest University, China, and the University of Bath and Lancaster University in the UK have come up with a method for determining android unlock patterns. The method uses video footage captured by a smartphone and an algorithm that can determine likely codes that match the movement of the finger or hand across the top of the phone. The system works when the footage is taken on an angle and is able to determine the pattern 95% of the time. The complexity of the codes does not help to defend against this kind of attack, in fact they are more vulnerable than simple codes.
Ye, G., Tang, Z., Fang, D., Chen, X., Kim, K. I., Taylor, B., & Wang, Z. (2017, January). Cracking Android pattern lock in five attempts. In The Network and Distributed System Security Symposium.
http://www.lancaster.ac.uk/staff/wangz3/publications/ndss_17.pdf
