Subsurfing a Curved Mesh

I am relatively new to Blender, and am trying to model a recurve bow. When I try to apply a subsurf to make it look smooth, the entire thing becomes connected end to end.

What am I missing?

Here are pictures of before and after the subsurf.


Hmm, these posts seem to be getting more and more common, even more so than posts about inverted normals.

Subsurf isn’t simply something you throw on your model in the end to make it look smooth. If you want to use subsurf, you should create your model accordingly, from the beginning. You need to have edge loops that define the shape of the model, and usually you need to avoid triangles etc.

Then what exactly should I do to smooth the curves? All I want to do is smooth the curves along the flat sides; I tried to use a curve but I had to switch to a mesh to make the modeling simpler.

What he/she meant is that when you use subdivision surface modifier on your mesh, your mesh has to be built that way. Good topology, face normals correctly, no floating geometry, no duplicates, no interior faces, no tris/ngons (except on a flat plane with perimeter loops). This might sound complicated but it’s not because Blender has tools to deal with these and you want to construct a clean model.

In the pics those look like they’re paper thin objects. You could start with bezier curve objects, turn it to 2D curve and optionally give it a dimension with extrusion (and perhaps bevel) values, turn it into mesh and continue from there. Or you could start with a mesh. Either way, if you use subdivision surface modifier for mesh, it has to be clean for it to work correctly. Idk why it doesn’t behave in your case, seeing the topology in the file might help.
You can upload your file in here and then post a link to it. You can’t attach a .blend file on the forum yet.

I see what you mean; however, the bow is not paper thin. It has dimensions in all directions, and a true thickness.
There is the full blend file, remember that I am very new to 3d modeling.

Everyone here has been at least some point. You have a problem and you’re asking for help, not criticism of your work nor comments of your skills. I don’t think anyone would make stupid comments because of that and if someone did, he/she wouldn’t be tolerated very long. So no worries.

So the reason why the subdivision surface modifier doesn’t work very well is because you have a single ngon on the side of the bow and interior faces in the middle.


Now if you were to fix this you would have to make that ngon face to quads but the problem you face immediately is that you don’t have the same amount of geometry on the front and backside of the bow. You could remove most of the edges from the backside and then bridge new faces because there’s way too much faces there.


You might ask that why there’s too much and the answer is that it’s very complicated to edit a dense mesh and you should only add it when you need it. The other reason is that you’re adding the subdivision surface modifier to do that for you, so you don’t have to handle so much topology.
I made a .blend file to give back to you. I duplicated a few steps so that you see the iteration and how much less topology you’re handling at first and how much faster it is to go towards much complex model.

Yes as JA12 said there is problem with that particular face. Since you are using 2.63 you are facing this issue because Blender implemented bmesh option. Previous version take 2.5x & 2.62.x series it doesn’t have b mesh option. It calculates only tries and quads. So while doing model with 2.63.x be careful with your poly.

Also i have found few vertex are not merged. I hope JA12 might have done in his file if not try to merge it by yourself. Also i found unwanted vertex, so please do remove doubles with your mesh. It will be Mesh–>vertex–>remove doubles or press “w” in viewport in edit mode and select remove doubles or in viewport in edit mode press spacebar and type remove doubles.

Thank you all very much; I’ll see what I can do, and maybe post on here again.

JA12, can you explain the steps you used to get from the beginning to the end? How did you deform the plane like that? How did you create the handles? And how did you smooth out the curves in the bow from Bow.005 to Bow.006?
Sorry if I’m asking too many questions…

Sure I can. But first I want to say that it’s just a sloppy example of how to start with simple topology and quickly turn it into shapes. You can be much more efficient with it, also more precise, and there’s important topology still missing, so don’t take this example as the way to do modelling. It was just a quick example, took a few minutes. My explanation just seems long because I’m not very experienced in making tutorials.

I did most of these in the front view (numpad 1)

  • Bow.001: I added a plane, rotated it 90° along the x-axis. keys: add: shift+a, rotate: r,x,90,enter

  • Bow.002: I scaled the plane along the x-axis and then along the z-axis. I approximated the height from the existing bow. keys: scale: s,x and then s,z

  • Bow.003: First thing, I applied the scale and rotation of the plane in object mode (ctrl+a -> rotation&scale). Scaling and rotating in object mode is not editing the object, it’s just changing its “representation” of it.

[INDENT]Then in edit mode, I added 1 loop cut in the middle, moved those vertices along the x-axis, and then added 1 loop cut to the upper half and then to the lower half. keys: loop cut: ctrl+r, move: g,x[/INDENT]

  • Bow.004: I added 2 more loop cuts on top and the bottom to get the bow ends to curve to the other direction.

  • Bow.005: 4 more loop cuts to the upper half and then extruded the edges that form the hole.

From top left:

  • Adding 2 loop cuts: ctrl+r, scroll wheel up, lmb.

  • Selecting edges to be extruded

  • Extruding twice along the x-axis. e,x

  • Planning to form the hole by extruding and choosing where to connect the forming face loop.

  • I used the quick way to extrude, ctrl+lmb twice, and then selected the 4 vertices that needs to be connected and filled it with a face (pressing f)

  • Too much work at that point, I didn’t want to do it again:

[INDENT] I selected vertices from the lower half, deleted them, selected the remaining upper half (all with a-key), duplicated it with shift+d, cancelled the move with rmb, mirrored it with ctrl+m and chose the z as mirror axis. Then moved it along z, changed the snapping mode to vertex (ctrl+shift+tab) and moved the lower half in place by snapping it to one of the vertices in the middle, selected all and from the specials menu (w) I pressed remove doubles.

  • I moved and scaled some edges and moved some individual vertices to make it more directed to the original bow shape. Just a few adjustments.

  • Bow.006: I added the subsurf modifier with level 2 subdivisions by pressing ctrl+2. Then, moved some edges and vertices a bit more to better shape the topology that the modifier gives. I also added one loop cut to the both tips to form them better, and one in the middle of the upper and lower half of the bow to make the faces a bit more evenly sized.

  • Bow.007: selected everything, and extruded the thickness, locking the extrusion axis to y. keys: select: a, extrude: e, y

Wow. What an informative and in-depth explanation. Thank you very much, JA12.