The Problem is I am trying to create a four way pipe junction that subdivides in a way that the points where the pipes intersect are consistently defined (See pics as to what I mean).
I'm looking for the sharpness of subdiv 0, where the pipes intersect, but want the smoothness of subdiv 3 (See pics below as to what I mean) and any suggestions in terms of how I might be able to change the topology to achieve this.
Requirements
I am trying to create a high res version of this pipe to bake to the low res version that will ultimately be used within Unity.
I've attached the blend file for investigation
A pic of what I'm looking for. Subdiv 0 sharpness with Subdiv 3 smoothness.
n3b The trick is to start with more base geometry, by that I mean a cilinder with 32 verts for example. That will surround the junction and keep it sharp (I hope).
n3b putting in "holding edges" is key to keeping sharp detail...
subsurf tends to round things out
hope this helps...
baukepost gave a great answer, the only thing that I'd add is that I would try using bevels instead of subsurf for this if you're aiming to bake this down and use it in Unity. The main reason is that the subdiv version is much more circular at the ends of the pipes, and that mismatch will make the front part of the baked lowpoly version look weird since the rays from the edges that poke out won't have anything to hit.