Displacement Map (Micropolygon Displacement) displaced weirdly I'm currently learning the process of baking displacement map through blender render in the version of blender 2.79.

Problem:

I find that the result using node for displacement map isn't very promising with those block-ish surface, while Displace modifier works fine, does anyone know the reason behind this?

Reason of one is preferable than the other:

I'm trying to get the node method to work since I've encountered problem with Displace modifier, it not only displace the differences on the character, like abs muscles, but deformed the others unchanged muscles like the mouth and face... Therefore I'm hoping that solving a simple case would solve the complex one. 

Two Blend files are included in the link below:


DisplacementMapNode - Referring to the Displacement map node set up.
Displace Modifier - The displace modifier set up.


If the displacement map is missing, please do leave a message, i'll upload it as soon as possible, although I believe I packed it into those blend files.

Any explanation would be deeply appreciated as I have tried to solve this issue for a day, Thank you and have a nice day modelling!
BlendFiles
You have forgot Material Settings Displacement set True



Also you able to manipulate displacement by Math nodes.