Bevel Modifier Rounding Method

Hi All, This is my first post. I am really loving Blender for modelling:cool:. Just a question regarding the bevel modifier. Recently I have been trying to practice some precise modelling and have come into a problem. I have noticed that the rounding method for the bevel modifier used does not give perfectly round corners? I am used to other software for bevelling. I have an example below. A. Blender default. B. Other rounding method. Has anyone noticed this. Or does anyone know if this being developed?


Can you show us an example of what you think it should look like? Nothing in life is “perfectly” round so I’m not sure what you need.

Hi Sorry I didn’t make myself clear but I have created a rounded cube with the default rounding on the left and precise on the right side.
You can really see the default rounding looking weird in the second example. I hope I have explained myself?

have you tried playing with the bevel settings?

You are kind of right, I guess, because the Blender bevel sacrifices a little ‘circularity’ for more perfect symmetry and topology. By that mean the bevel looks exactly th same from every face, and the edge loops are completely continuous. The ‘other’ method - did you do this by hand? - will have shading problems at that vertex where the triangles come together. It has severe topology continuity problems, as in edge loops running in one direction only - just that one thing makes it a bad choice for anything other than a cube corner, whereas the ‘blender’ method is adaptable to a very wide range of vertex angles…

Also I think the problem you are showing here is largely avoided by picking an ODD number of segments, which results in the edge being replaced by an EVEN number of edges, which means that there won’t be a single ‘point’ vertex.

Yes even the bevel tool ctrl-B gives similar results. The only way I could replicate precise rounding is by using a of quarter of a sphere and match the loops. I was looking at the Blender 2.4 bevel tool and it had precise bevelling as default, so perhaps they changed the method . Anyway just an observation. Link to the 2.4 bevel method
http://wiki.blender.org/index.php/Doc:2.4/Manual/Modeling/Meshes/Editing/Subdividing/Bevel

Hi DruBan I have posted links above on my first post. You are right about the triangle on the first loop I usually take out every second edge to make it a quad. But suprisingly it give the best rounded edge. I only noticed this this because I am modelling an Apple USB iPhone recharger the differences are astounding to me! pics below
Blender 2.68


My method

Yes the bevel tool was changed - some say upgraded -in 2.6 maybe? Your pic makes the problem for 90 degree corners quite clear maybe they should have left the option in. I usually do this sort of precise geometry with curves and the bevel object in curves is very precise. But vertex intensive! If it is a product shot you can leave it as a curve and it renders smoothly.


Hi DruBan that looks very rounded could you give me a quick guide how to do that if possible? Thanks in advance

Sure. If you want to work with curves there are many ways to construct objects. I am not going into all of them here, but you can:
Use a taper object, use a bevel object, import your paths from Inkscape (it’s easier to draw in it), use the Bsurfaces add-on, Use Bezier curves, use NURBS curves … say! Why don’t we do that! It’s the fastest! (In the interests of disclosure the above example was modeled from a Bezier rounded rectangle imported from Inkscape and extruded and beveled in Blender. But a NURBS curve from Blender is just as nice!)
Let’s get started:


Whoa! Done already! Told you it was fast!

So okay there’s a large Ngon. I have found no smoothing problems associated with it. If it’s a problem it’s super easy to delete the face, select the opposite edges of the loop and use grid fill to fill it with quads.

Here is the result of the beveling command in edit mode, very bad too
it even makes negative angles…


from the side


from the top

paolo

It is darn tedious, but if the corner vertices are selected and 3d cursor is where the center of the sphere they form would be, To Sphere = 1 makes such corner useable.
I wonder if that could be feasible to program such an option in the Bevel mod or command itself.

So far if you put these side by side, well, one can see the difference, really.

Mathematic is not an opinion, both the editing command and the modifier do wrong calculations, period.

paolo

Druban Thank you for that detailed explanation I will experiment with that

Eppo interesting idea I will try that as well thanks

If the Bevel does something that wrong, you should really report it on the bug tracker so it can get hopefully fixed :
https://projects.blender.org/tracker/?group_id=9&atid=498

Maybe you are right Sanctuary, I thought to avoid to report since it is not strictly a bug, and probably it would need a good redoing at the proper time, what do you think?

paolo

From what i remember Howard Trickey has updated his Bevel code several time to fix some bugs in the last few versions, so maybe this one is either a side effect of a bugfix or something new none noticed before (i never noticed that until i saw the screenshots on this thread), but from your screenshot showing the negative angle, i think it’s really not supposed to work that way.

I remember beveling oddity since long ago, cannot say if it had the same behavior though.

OK I will report it, the devs will judge better than me.

EDIT: Submitted: 36462

Thank you,
paolo

Thanks, i think it’s always a good idea to report something when we think it’s wrong.
If we’re mistaken, the devs will see anyways, but if we’re in the right, the dev may be able to fix the problem and it will benefit everyone.