How to have round edges when I subdivide with a subsurface modifier? In the image you can see sharp edges, this problem was originated because I subdivided (Key "W" then Subdivide) the selected faces with a subsurface modifier of 4 subdivisions.

How do I make these sharp edges convert into round edges like a "Normal" subsurface modifier? Or like the edges of a cylynder/sphere.

NOTE: I need a lot of polygons-vertices because I have a "displace modifier", maybe you can help me find a way for displace modifier (With not a lot of polygons) instead of resolving this one.

I have tried with:


Smooth modifier, result is good on another mesh but with an error too, but in this one isn't working as I expect.
Smooth tools. It's quite good for my displacement modifier but it doesn't resolve the sharp edges.


EDIT:


Doesn't work with Subdivide Smooth too.


EDIT2:



What I want is everything marked with the red circle (The sharp/hard edges) turn into soft edges like the surface of a cylinder.

The problem is that I requires subdivide and the subsurface modifier because of the displace modifier (I need a lot of polygons).

Thanks for the answer.
Remove unnecessary edges(follow this instruction) after that you could add your modifier