Can Rhino create the same quality as Alias in class A surfaces?

(Alex) #1

Can Rhino create the same quality as Alias while you don’t use any SubD plug-in and just use its native curves and surfaces?
Which one would give you better control?

Why cannot fillet command produce G2 continuity?

No Rhino cannot create the same quality. Rhino lacks the matching tools and more important Rhino has no analysis tools for class A surfacing.


Well, for what exactly? “Class A” is a meaningless marketing buzzword.


In my experience yes, but it takes more time and there is no good history implementation.

But Alias can do 1 thing, rhino is much more flexible.


That’s not true. There are methods and standards to Class A.

(Tom) #6

in danger of creating a shitstorm… the term class a is originated in automotive industry. its by no means a marketing buzzword however talk about gets very religious.
for a long time even alias wasn‘t the tool for class a in automotive. I never heard from a german car brand that made final surface models in Rhino. Last year I even saw Tesla looking for people doing class a with icem surf. Industry standart for class a surfacing is still Icem Surf. However Alias is getting pretty close and some oems already replaced it for class a.This is also because Icem Surf isn‘t develloped much further.
Now the problem is that a lot of people don’t really know what it is,because they never did it professionally (in automotive). If so nobody would like to do class a in Rhino although you can create very good surface models with rhino.Out of question!
But:Applying principles of class a doesn’t mean to model in class A. As Cadworx said, in Rhino you cant even analyse if you fulfill criterias of class A and that is the most important aspect.
Its also a misbelieve that class a means that it is superb modelling or that is always needed.Its basically just very accurate modelling, controlling light reflections for objects with highly reflective materials. Most modelling is done in class B for invisible and technical parts. It can get very boring and its not always worth the effort. I also must admit that no every rule makes sense. But comparing Rhino with Alias and Surf or comparing Subd surfaces with nurbs patches is like comparing apples with oranges and you should definitly stop doing these comparisions if you dont know both worlds


That’s true but it existed as a tooling classification and standard and was used long before there were CAD programs and anybody was babbling about G2 surface continuity.


VSR Shape adds the tools to do Class A with Rhino.

(Tom) #9

this is true. G2 isn’t everything and I’m one of those few in this forum who constantly say that there are situations where a good g1 transition is better as having G2. This is also my critic on Sub-D, because it assumes that if you have g2 everything is good (although Autodesk indeed points out the weaknesses and even says that sub-d is basically just for concept design, but for this stage its powerful).
Yesterday I was bit harsh. So @JimCarruthers has also right in terms that class A is misused as a commercial buzzword, in a way that a lot of people claiming to produce class A, but they actually don’t.

@Stratosfear: You probably know this, but VSR is dead and there is no recompiled version for Rhino6. So sadly there is no “class A” - plugin anymore. Besides that, VSR wasn’t fully complete. Some vital functionality was still missing, however analysis tools were great

(David Cockey) #10

Autodesk/Alias on what “Class A” means in the auto industry: It is significant that they talk about the refinement to Class A occurring at the end of the design process.

Discussions about “What is Class A surface quality” and “How to achieve Class A surface quality” seem to be frequently confused and mixed together. When the overall surface is released so that tooling can be made my guess is what matters is the quality of the surface and its conformance to criteria, not the details of how the patches are organized, the degrees of the surfaces, whether single spans or multi-spans are used, etc.

(Alexander Petrov) #11

Hello, I think Rhino and Alias are incomparable at any way! I use both, also I use VSR Shape, and according of my point of view these softwares are designed to achieve different goals. If you want high quality results with lots of explicit controls, then Alias / Catia is your software, if you want flexibility and speed then you should choose Rhino. Alias is designed for comfortable work with CV-s, Rhino is not! Even VSR doesn’t have good CV manipulation tool. Compared to Alias’s one, they are incomparable. Also Alias has Explicit control, which mean control over the quality of the surfaces at every stage of modeling process, Rhino doesn’t have such functionality. Alias is well designed for manual (direct) modelling, Rhino is not. Direct modelling is essential for achieve high quality results, where automatic tools fail is the beginning of manual tool i.e. the hand :slight_smile: There is no Class A without direct modelling, but this scares a lot of modellers, because it requires a lot of practice to “feel” the proces for itself.

(Rob McPherson) #12

Yes, but all these points help you create the cleanest and most manageable geometry while on your journey to an acceptably finished part, which often involves many modifications from the designers and engineering input for feasibility (the cleaner your model, the quicker you can modify).

(David Cockey) #13

How is Rhino not designed to work with control points?

(Pascal Golay) #14

Hi David - I think it’s more the UI for doing this - how smooth and convenient the motion of the points, the feedback from changes, useful constraints, that sort of thing.