# Subdivision Surface on curved mesh

I'm trying to delete those ugly lines visible in the cylindrical shape of the lens. What is causing them is the added edge loops I made for the protruding detail with the switch. The problem is that if I delete those edges, it'll look even worse because of the n-gons. Any ideas?

I think your problem is how you place edge loops in your mesh over the curved surface.

Since it is a cylindrical surface edge loops cant be placed by simple subdivision, because that will yield a flat planar surface breaking the curvature of your otherwise cylindrical body.

When placing edge loops you need to make sure they are equidistant from the mesh center or use Subdivide Smooth for a curvature approximation.

• Excellent. I'll make sure to do that next time. Although I just tested Subdivide Smooth on a cylinder and those lines appear if you make enough cuts. The lines are noticeable even when doing 2 cuts: Picture The thing is that I can't do it that way on my model without deleting the protruding detail. What would be perfect is an add-on that lets you line up the vertices with a desired radius from the origin of the cylinder. That would solve everything, if what you say is right. BTW, how did you slide the 2 edge cuts you made at the same time, at opposite dir? Jul 23 '16 at 16:04
• Well I'll be frank, fixing your model probably won't be easy without remaking at least part of it. Unfortunately this kind of work is more suited for CAD like NURBS or Solid Modelling applications; Blender is particularly unsuited for this type of workflow unfortunately. For this I would suggest the spin tool Alt+Rthat uses the 3D Cursor and the point of view as center for generating flawless revolution geometry. Jul 23 '16 at 17:32
• The two edge loops sliding were actually created using the bevel operator. Select one single edge loop and press Ctrl+B and it will create two parallel loops using absolute distances. Jul 23 '16 at 17:33
• Alright, I'll remake the detail. Thanks for the bevel tip! That'll be useful. What do you mean by "this kind of work", exactly? What "type of workflow" are you referring to? Jul 23 '16 at 17:44
• I'm talking about solid modeling of geometric shapes or "hard-edge" type of objects like mechanical parts, non deforming or non organic shapes, based on precise measurements and intersections of basic shapes. This thing is usually done in CAD applications like AutoCAD, Rhino, MoI 3D etc, where you can easily use Boolean operations, extrusions, revolutions, intersections, trimming and extending, and beveling for perfect geometry and smooth curves Jul 23 '16 at 17:58

Cylinders and spheres are prone to render errors when they contain faces of different sizes. In your case the switch also produces irregularities not only in the horizontal but also in the vertical direction (both top and bottom of the switch)

As far as I can tell your model is already made out of several objects/meshes. If it's not absolutely necessary to have the switch and the tube as one single object I would separate them and collapse the unnecessary edge loops.

• I didn't bother about joining all the parts because this is just a high poly model to bake a normal map to a lower poly model, but I want to avoid dividing the mesh further because it may become cumbersome. I'll do it if it's the best choice, of course, but is there an easy way to even out the size of the faces of the cylinder without deleting any edges? Jul 23 '16 at 1:08