faceted cylinder

faceted cylinder

Hi all. I'm working on a science illustration here at work and I've been trying to render some objects that are cylinders of varying diameters. The way the material is interacting with the lighting makes them look smoothly round, but the sharp edges still show the faceting of their polygons. I tried using a subdivision or smooth modifier but that smoothed out everything. I still want the edges that represent the diameter transitions to be sharp. I'm sure this is something basic I'm doing wrong but could you help? I've attached a render.

Thanks.

So is the trick selecting just the edges or polygons you want to subdivide instead of the entire object?

you need to place edge loops close to either side of the edge/corner in question, then apply a subdivision modifier.

look at the 3 highlighted edges in zoohead's gif.

--shift studio.

Ahhh. Ok. Off to try it. Thanks.!

Well it wasn't really working, but then I tried it with the form you had, the disc with shell applied. That worked perfectly. It was much easier to add the ring cuts to that shape than the cylinder. Thanks.

I´m not getting why one will add unnecessary geometry when we have a proper bevel tool:

Cheers
Frank

I’d use a subdiv + the added loops so I can use an 8-12 sided cylinder rather than 32+ sides. I generally use subdiv on everything. I see your point too though - I tend overdo things. :redface:

— shift studio.

The downside of subdiv is you get extra geometry in places you don't need it. If you don't want the cylinder to be curved along its long axis, subdiv is doing terrible, terrible things to the complexity of your mesh, whereas a straight out cylinder is giving you exactly as much geometry as you need.

Aside: in a NURBS modeler (like MoI) you can have geometry added based on the degree of curvature (e.g. is there a "break" of more than some threshold angle (e.g. 5°). If you have a NURBS-savvy rendering pipeline (e.g. Maya) you can add geometry on-the-fly based on the above and also whether the polygon in question is larger than some specific size on screen (e.g. a pixel).

NURBS modelers where the craze some ten years ago. Now the only big name around that comes to my mind is Rhino. They are great for hardsurface modeling, but not so much for organic stuff.

And yeah, Subdiv usually produces too much geometry, while an object like this often enough can be done with enough edges. And in a lot of render engines the somoothing options allow to use quiet crude geometry rendered with rounded edges. So you have with a good subdiv modeler and renderer usually the best of both worlds.

One trick is to subdivide once, then kill a few unnecessary loops, but one of the most important things is to learn when it's better to let it be :smile: And even knowing that I'm still 'programmed' from years ago by using lightwave to prefer subdiv, because the lw-beveler back than was often a sure way to destroy a model. Cheetahs beveler on the other hand is quiet capable.

But Frank is right, when possible just use bevel.