Linear Interpolation (Wikipedia)
https://en.wikipedia.org/en/%E7%BA%BF%E6%80%A7%E6%8F%92%E5%80%BC
Linear interpolation method (Baidu Encyclopedia)
http://baike.baidu.com/view/4685624.htm
Linear interpolation function of UE4: FTransform::LerpTranslationScale3D