# Adding Subdivision Surface Messes Up Geometry

So I'm working on this geometric shape that looks like this:

I've converted to tris and then all my tris to quads. So there shouldn't be any ngons left in the geometry. I've also recalculated all my face normals from the outside.

Then I add my subdivision surface modifier and I get quite a few distortions/pinchings/crumplings:

and here is a view where I add more levels:

How do I go about making the geometry smooth out better? Do I need to do some topology type stuff? Or is my geometry all messed up and needs to be remade?

Edit:

here is the blend file -

• You need more supporting loops for subsurf to work well. Topology Guides is a good resource to look at. Dec 23, 2020 at 17:35
• Another issue in your case is not tri's or n-gon's, but poles (vertices with more than 4 connecting edges). These are causing your "pinch points". Like tri's and n'gons, these can be acceptable, but try to keep them towards the middle of flat areas. Dec 23, 2020 at 17:41
• @ChristopherBennett - how do I go about reducing/removing poles? Dec 23, 2020 at 17:50
• It's mostly a topology practice kind of thing, so there's no real one-size-fits-all solution. However, one thing you could try is to go into the Object Data Properties tab, and under Remesh, pick "quad", and try running the Quadriflow Remesh. It works like magic on some things. Dec 23, 2020 at 17:53
• @ChristopherBennett i don't have the quadriflow option. I only have these options: blocks, smooth, sharp, and voxel Dec 23, 2020 at 20:29

The first thing I noticed (by turning on Face Normal overlays) is that the normals were going all over the place. To me, this suggested duplicate faces, so I used a Merge By Distance operation (Press M (Merge) in the viewport and select Distance). I increased the Merge distance to $$.0101$$ and it removed 521 duplicate vertices which solved most of the problem, but not all.