Subsurf: Extrude a cuboid from a cylinder without ruining the cylinder's form

Support Modeling
1

I still cannot seem to get my head around the simplest tasks in subsurf modeling.

This time I want to extrude a cuboid from a cylinder:

Bildschirmfoto 2013-10-25 um 22.11.34.png589×593 153 KB

As you can see in the last picture, the cylinder’s round form is damaged due to the vertical detail loops.

What would be the right way to do it?

2

Try creasing the edges instead of adding edge loops.

3

You should move those two loops closer together above and below the extrusion so that the verts are evenly spaced, or wedge it out. Post file and I can try to show you.

4

Here is the topology if you want the joining absolutely perfect. (Subsurf level 1 in the back but that doesn’t do much as far as shape goes)

cylinder_rectangle.jpg1280×1024 92.5 KB


For very sharp corners, the key is to get 3 vertices per corner: one in the middle and one on each side that sharpen the shape. On a curved surface, the surrounding faces need to be somewhat evenly sized. In this one, some of the horizontal edge loops are not needed so those can be taken out.

5

Try to add new object, more easier to handle afterwards also and local polycount is big plus always + less shading problems.

6

First of all, thanks for your once again very quick and good answers!

Try to add new object, more easier to handle afterwards also and local polycount is big plus always + less shading problems.

@TynkaTopi: You mean adding a separate mesh for the cuboid? But then I would loose the soft joints between the cylinder and the cuboid…

@JA12: I tried to keep the vertex count as low as possible. You’re compensation the problem by increasing the resolution. I was hoping that there is a way to solve the problem without increasing the complexity.

Try creasing the edges instead of adding edge loops.

@m9105826: The creasing gave unwanted effects and it is not possible to precise yet rounded edges along the cuboid.

7

How about Knife Project with plane.

8

If you want the surface to be smooth, you need geometry, you also need some or all of that geometry to be in the editing cage if you’re defining hard edges with it too. Mine without subsurf was 512 faces, yours in the pic is 304 with subsurf level 1 (not counting the ngons on top), increasing that to subsurf level 2 would give you 1216 faces.

Of course if you don’t want/need it perfect, something like this could do as well (376 faces with subsurf level 1)

cylinder_rectangle2.png1280×974 172 KB


In that one there are two vertices to define a corner and the rest are adjusted with edge creases.