Retaining rectangular form of extrusion after applying Subdibision Surface while keeping topology clean


I’ve been trying to wrap my mind around this task for a while struggling to create something similar to the extrusions like on the front of the reception desk in the example.
I want to put the resulting mesh into a Subdivision Surface to get curved geometry in some parts of the object.
Until now I was able to get away with simple but messy solutions like making lots of control cuts along the edges, but it makes the rest of the mesh almost impossible to work with.
Of course you can do this just by inserting these elements as separate objects, but as a beginner in traditional modeling I would like to know a possible way to get around this while using just one mesh.
I also tried bevelling and loop cutting.
While it provides a better looking result, the end topology doesn’t look clean.
Does anyone know a workaround for this? Thanks!!


Have you tried the Bevel effector on edge selection ?


Thanks for your reply! Unfortunately it bevels the vertices at the corners and the quads around it turn into n-gons. As a result messes up the mesh after subdivision :(.


Actually I proposed using the Bevel effector instead of the Subdivision so you could subdivide only those points/edges/polygons that interest you via the points/edges/polygon selection tag. You can have different Bevel Effectors for different selections on the same geometry.

I thought that would give you the desired appearance since your model is a furniture and not an organic form.

If you need to retain the main big surface behind your extrusions untouched select only the points/edges/polygons at the end of your extrusions .


It may not be the method you’re looking for, but,
as in the real world … desk profiles are made from several components.
That being said … lofting would work like this:


Oh I see. Your method can actually solve my issue. I don’t think I need the whole object to be subdivided, only a few elements, and it works perfectly for that task. Thanks!


That should work well too, thanks! Is it okay to compose end models from several elements? Most of the downloadable models of furniture consist of a single mesh, that’s why I’m concerned.


Actually it depends on the type of model and the use it is intended for.

A very complicated mesh could be comprised of several objects. That is useful if you want to assign different materials to different elements fast and be able to make adjustments to those elements later.

Clean topologies and closed surfaces are best when working with other people, intend to use your model on other applications, use them on games or sell them. This can be tedious but shows that you have skills. Of course this is’t always case, for example modelling a robot without keeping its joints as separate objects will make it unposable.

While you model inside Cinema4D and work with your models only inside Cinema4D you probably want them to have their parametric structure and hierarchy in case you need to change them later. As you progress your scene and things get heavy for your hardware you will have to convert them to Editable, Connect+Delete, Optimize, Convert Current State to Object, Bool to Unify to Single Object etc…


I was able to obtain this kind of topology by adding quads to the corners. It still adds some more lines to the overall mesh, but it sure looks cleaner and easier to work with. Funny enough, I stumbled on this technique just now while watching a MINGW11 tutorial on convex cuts



Thanks Demis for your detailed reply!


The algorithm under the Subdivision Nurb is trying to smooth the underline topology. But it is also driven and constrained by it. By adding outlines to corners you constrain it from smoothing the corner with the topology prior the outline.

You can also do these by selecting your original polygonal model’s points/edges,polygons under the Subdivide NURB


Didn’t know you could do so much with the Subdivide NURB. Could you please show or tell about some examples where you can apply these techniques?


If you want to subdivide those structures

or this guy here


You will loose those spikes due to smoothing.

But by using weighted points on those tips (on the creature’s head) you will retain their original form but with more polygons.

As for the structures using the polygon weight on the top of the chimneys will retain their cylindrical form without spherifying their tips

Generally someone would use the Subdivide NURB to make a hi-res of a low-res organic form.