I know that “Class-A” surfacing is a marketing buzz word () , but I think that Rhino 8.0 is rather competent to do so called class-A surfacing as long as it means certain tolerances only and G1, G2 and G3 continuity only. Rhino has a nice edge tool now days and also curve tool can diagnose the surface continuity level.
I have developed a simple but effective(?) method to do Class-A surfacing with Rhino and it is a free macro tool at:
Please give me opinions and ideas to make my project to progress.
I do not think that Rhino is reliable enough to work and build Class-A. It is typically not considered the primary tool for creating Class A surfaces. Car designers use it to make the style presentation model, and pass it to other software to make the final class-A 3D.
While Rhino is a reliable and powerful 3D modeling tool, it might not be the most straightforward or specialized option for creating reliable Class A surfaces compared to CATIA and Autodesk Alias. But maybe one day!
CLASU is a solution I believe. CLASU could work in CATIA too but not in Alias, cos you cant write own macros in Alias. I am looking forward to make CLASU for CATIA too. The principle is the same, Rhino or Catia or whatever system. The point is to make curvature seams easily. With this F 40 I have putted tolerances as high as possible. The file became very heavy of course but I should test it with Alias seam tools now. I have no license for Alias that but if somebody has he could download the file from GrabCAD and make a test later when this F 40 is fully ready for an acid test. It is of course my interest to see how far Rhino is from Alias now.
(Actually I did some premilinary test after exporting from Rhino to Alias as IGES, and the results were promising. But soon the trial Alias locked up and I removed it. The tests were only starting point and nothing more. I think some IGES seams which are curvature in Rhino are curvature in Alias too, if tolerances are really high in Rhino after export. But my testing was left unfinished due to trial edition lock up.)
I honestly don’t understand why would anyone use this instead of native matching tools like MatchSrf? And if I understood your macro / script correctly, it is basically just aligning control points to straight line…? This is very basic control point manipulation and nothing more.
Match surface creates surface seams which are crap. If situation is complex enough like in this F 40 it is unnecessary tool entirely due to bad idea of the match surface tool. If you make the seam by hand with CLASU the result will be good - with very few isoparametre curves. Always. CLASU is in a very primitive form yet but it works cos it is simple and solid idea.
Here is an example of this F 40. It is backwing only. If you open it, explode it and start to investigate with with edge continuity tool you will find out that it is not that bad modeling work. All main surfaces, which are important from the aerodynamic point of view, are at least tangent G1 continuous and there are G2 level seams also, maybe even G3 and G4 level seams also. It was very difficult to make this rear wing, guaranteed as fully continuous. The roundings are not that good, but seams of the patches should be.
I promise that most automatic tools are helpless to do a surface like this with only a press of the button. Maybe AI will do that in the following years, and it may not take even too much time, but before that a surface like this is best to do manually, I think. You can correct me by showing that you can make this - without AI - simply by using Match Surface tool. Please put your file then online. backwing.3dm (16.9 MB)
dear @Tommi_P_Laiho1
not sure if I completely understood your workflow - but as far as I could see it is mostly about aligning control points to one Line ?
and the script helps to draw this line ?
Did I miss something ?
What does your script do different then the rhino command _line _fourPoint
To align CVs to a Line my workflows are:
_cplaen (by z-Axis)
_setpt (x,y, cplane, to 0)
Yes. The macro works as it should. You need to align the CV points of the patch - all of them - to the opposite patch and it becomes continous. The more CV’s are aligned the better continuity. That is all what is needed to have perfect seam with the patches. The becoming curve is a “tangent ruler” which is all what is needed for a perfect seam. The approach is very simple but it works.
I tested “_line _fourPoint”. I do not know whether or not it is a NURBS curve, which may be more accurate than polygon line, but “_line _fourPoint” indeed works as well. The point is that you can now use this “_line _fourPoint” function to make Class - A surface as an easy and intuitive way, if you follow my method and advice. CLASU makes a NURBS curve, that is for sure, I think.
I don’t want to start another class A surfacing discussion (there are already too many of them here), so let’s put it bluntly, please don’t take this personally:
Autodesk is not going to loose any sleep over your new, “effective” method.
You have completely missed the point of what Class A modelling is about.
Your example surfaces don’t fulfil even the most generous requirements to class A surfaces.
Thank you very much for your valuable comments. Would you like to show exactly where my modeling does not fullfill the Class-A surface requirements?
I am all ears to know. This is very important. Take a look of this inclosement. I know that some roundings are not ok, but the spoiler should be. backwing.3dm (16.9 MB)
The controlpoint distribution on your multispan surfaces is all over the place.
Even to the naked I the discontinuities between surfaces are visible, but let’s have a look at a zebra/light line analysis:
The matching analysis shows that unsurprisingly the surface edges are discontinuous.
Trying to model the complete front fender and its adjacent surfaces (top, front and side) in ONE multispan surface is completely contrary to any reasonable class A modeling approach.
So even if the surfaces would mathematically match, there is no real use in this method as it is totally unpractical in trying to achieve the desired shapes/design intend in a controlled manner.
Ok. Many thanks for reasonable feedback. I wanted to see this image.
However this does not make the CLASU futile. It just is that I should make the surface from smaller patches and not use so large areasin the front nose of the car. However Rhinos seam tool says that the surfaces are continuous. Is this the limitation of the RHINO, I do not know?
Anyway the spoiler is good. There are only few main seams which are made with CLASU. And THEY ARE OK. The roundings are made with RHINO AUTOMATIC TOOLS. THEY ARE OF COURSE BAD.
Dude, most of the surfaces don’t reach tangency, often not even positional continouity.
The spoiler is neither okay mathematically, nor from its modelling approach.
But whatever floats your boat, I guess.
If you mean that G3 is the only way to go, then you are right.
If you think that G2 (pink) is the surface good enough you can see that most of the seams are at G2 level.
I can see in this spoiler only few G0 (red) labels. This is clearly wrong.
My target was not G3, cos I have understood that G2 is ok and also G1.
I will remake the surface with G3. It is as well as possible as G2 or G1. It just needs much more isoparameter curves and maybe a different geometry too. I will later proof my concept better, stay tuned. Thank you that you measured my model.
The red circles which I have done show the seams made with CLASU.
Just for your information: the pink dots indicate that g2 is NOT reached according to the criteria seen in the menu.
Same goes for orange/g1, turqois/g3 and red/g0.
The white dots indicate edges that pass all criteria.
That means that not a single of the transitions you encircled is okay.
But it is reductive to think that edge continouity is all there is to class A…
Why don’t you try to do this CLASU method with Alias, once you have it at use? Please do. Maybe it solves the problem? If Rhinoceros is too inaccurate to do Class-A surface, my method will not ever work then in Rhino?
I have included one image of Rhino seam tool. The green sign should be a good sign, if there is any logic in this seam tool. If it is not, the manual of Rhino is indeed rather bad. Very unintuitive, at least.
If there is a similar tool like four point curve tool in Rhino you will soon check whether or not there is any sense in my idea how to do seams in modeling work. Be curious.
Where are you trying to go with this? You say that you invented this method 20 years ago. What has it been used for since then?
The example you picked seems to be a little poor, and beyond that, for a tool demo, you’ve only shown a final model and haven’t even clearly explained the intended workflow.
) , but I think that Rhino 8.0 is rather competent to do so called class-A surfacing as long as it means certain tolerances only and G1, G2 and G3 continuity only. Rhino has a nice edge tool now days and also curve tool can diagnose the surface continuity level.
