parrallaxing / pixel depth grass shader

monodrobe

I really like this shader for grass that they designed for act of aggression, Im trying to backwards engineer it. I feel close but missing some important elements. Or maybe Im way off

[media]https://youtu.be/5DF16_F8PiI[/media] 
[media]https://youtu.be/B6uVf7aHolc[/media]

so i ve played around with a basic noise texture as a height map using bump offset in ue4 and i can get the  vertical parrallax feel of the grass, but theirs has distinct caps to the grass which i can t figure out

but more critical is how theres interact with objects, take note of the rock. I suspect they re using something like pixel depth offset along with the vector of the camera. I havnt been able to reproduce the effect but I ve yet to try incorporating the camera vector into my shader yet

Love to hear opinions on how peeps think they did this and if its possible / how to go about it in ue4

thanks