I’m starting to play around with subdivision modeling, and it’s generally going well (I’ve been trying various programs, including AoI, Wings, and Blender). However, I’ve just run into a little problem in Blender 2.66a. I have a subdivision surface, and I’ve got it making a shape that I like when smoothing is applied. However, the topology needs fixing, so I want to add an extra edge loop as part of this process.
And here’s the problem: when I add that extra edge loop with Loop Cut, the model puckers (I think because it’s putting the new edges on the unsmoothed surface, then applying the Catmull-Clark algorithm and getting a different result). I have heard that Loop Cut and Smooth is supposed to be able to fix this, but I can’t get it to work.
So…how can I add an edge loop to a subsurf without changing the final shape?
I don’t think that is really possible. It’s a matter of “one has to come before the other”, the loop cut or the subsurface.
You could apply the subsurface first, and then do a loop cut. That would maintain the shape. (yet lose the flexibility of the modifier)
Having the loop cut first shouldn’t be all that bad (if the mesh is done right and has quad polygons), it will change the slope of the smoothing, but nothing so severe as “Puckering”.
Do you have a picture or a .blend file demonstrating this? Because “Puckering” makes me think that you may be using triangles, which often have that kind of problem when subsurfed. Quads are a pretty key part to making a mesh that subsurfs properly.
Here are pictures. “Puckering” may be too strong a word, but it does change the shape of the object – note especially the top “suitcase corner”. The difference isn’t huge, perhaps, but it’s there, and it’s more than I’d like it to be.
What I’m really trying to do is fix the topology of my mesh without significantly changing the surface. How do I do that?
Reading that thread is what made me realize that I wanted to fix my topology in the first place. The problem is that I like the smooth shape that the model currently has, and I would like to preserve that as i fix the topology. And that’s what I’m asking for suggestions on.
If you want to retopologize it from scratch you should add a second object, preferably a plane, and use snapping (the little magnet icon at the bottom of the 3d view) to keep it against the shape you’ve made while you create better topology. Look for tutorials on retopology.
Thanks for the suggestion; I’ll look that up. What I’d started doing was taking screenshots of the “before” object, and using them as reference images on the “after” topology to get the same smoothed surface again.
Just to be clear: you wrote “If you want to retopologize it from scratch”. Are you saying that’s what I should do in this case? (I’m perfectly happy to do so; I just want to understand an optimal workflow.) Thinking about it some more, though…what happens next time I need to cut an edge loop into the object? Am I going to have to go through all this again?
Your topology on this model isn’t going to be improved by adding loop cuts. Your edge flow needs to be completely changed. It is what you should do, but I was making the suggestion gently.
You needn’t be that gentle; I’m trying to figure out how to do this right. I thought I had proper edge flow except for a few spots. Apparently I don’t. What do you see as the problems?
I thought I had proper edge flow except for a few spots. Apparently I don’t. What do you see as the problems?