Detect chin rest position of face - opencv

[opencv_Beginner99]

Hi,

I am developing a face morphing application using opencv & Java.
I have detected face features.

Tried using contour detection and other edge detection algorithms.
Still not able to find the logic to detect the chin rest points.

How to find the shape of face...? or
How to find chin rest position...?

Kindly plz guide me.....

Thanks.