How to properly model a car ?

[kleinsylvain]

Hi everyone,
I'm new here and if I'm posting this here it's because I didn't find anything helpfull about this topic elsewhere online...

My question/issue is "what is the good and effective workflow to porperly model a car ?"

Have you good exemples of high quality car model done in Fusion with the workflow you used ?

I now the T-Spline way but it's seems "basic" and strange that the best way of modeling a car into a cad software is to use a polygonal workflow. If it is, I would prefere model a low poly version in Maya and convert it to T-Spline in Fusion360.

Is their any good way to model a car using spline and patch mode ?

If you have good tutorial/examples/videos about this, I'll love to see them 🙂

Thanks.

[jeff_strater]

if you are talking about concept modeling of the outer body of a car, I'd highly recommend Grant Holmberg-Baugher's Youtube channel:  https://www.youtube.com/user/GHB503.  He's the master of car body design in Fusion using T-Splines.  I suspect you will re-think your opinion of T-Splines as "basic" after watching those...

[kleinsylvain]

Hi and thanks for you reply and for the link of this youtube channel but I already came across of some of his video and this is not mean but yes I think the cars he model are "basic" in the way that everything is one big "blobby/rounded/smooth" shape... (see picture attached)

I already know how to model a highly detaileld car in polygonal software but for a spefici project I need to work in CAD environnement (specificly Fusion if possible) and when I started to learn Fusion few month ago I dreamed about creating a car using spline and controlling every surface and finishing it with loft/boolean/cut/etc... to detail it.

I tryed using spline in the shape environment and creating surface using patch operations between them but the issue is that the surfaces seems to not be tangeant to each other and as a result you see the seems between each one... wich is not workable for me and my need of course.. (see 2nd picture attached)

If anyone have a fixe for that or a different way to go 🙂

[TrippyLighting]

I don't really know what your background is but is it unlikely in CAD or modeling.

Anyone who knows how to model a decent car in a Sub-D  modeler such a Maya, MoDo, Blender C4D etc. also can do that   in Fusion 360 and there are a number of examples available. It is not a mater of tools, but a matter of skill!!!

If they did have any of these tools available they probably would do do that in Fusion 360 because Fusion 360's T-Spline tools are somewhat limited and somewhat clumsy but they do work. It just takes patience and practice.

Real production ready vehicle designs are usually not done in either! Fast prototype designs might be done in a Sub-D modeler or Fusion 360, but more likely with Autodesk Speedform, which also uses T-Sppine technology under the hood but has a more developed tool set.

Production designs are usually done in high end surfacing software such as Autodesk alias or ICEM surf.

These tools allow much better control over the curvature of the surface than the usual main stream CAD tools including Fusion 360.

Many of the people that do car models in the patch environment have never used any of the inspection tools available in Fusion 360 and don't understand some of the basic premises in modeling vehicle surfaces, such as curvature continuity.

As opposed to these surfacing approaches in Fusion 360 where curvature can become a real problem, T-Splines are naturally G2 curvature continuous.

My recommendation would be to watch some tutorials on how to model a car with T-Splines. While the tutorial below is a Rhino tutorial, most of the tools they are discussing are the same in Fusion 360 so don't get hung up on that.

Focus on the general approach:

The gentleman who does the modeling is an industry professional and knows what he's doing.

'

Another god one to watch is this Autodesk University class. One of the speakers is also a professional in the industry and here are his Fusion 360 gallery entries.

While he's hard to understand, in the class he demonstrates a number of neat workflows. On the other hand, these might only be picked up by someone who already has a bit of experience modeling with T-Splines.

If you are new to modeling altogether I'd strongly suggest you start with something simpler than a car. 

[kleinsylvain]

Thanks for you reply !
you get right about my issue trying to do this in Fusion when you talk about surface continuity and other highend softwares specificly made for this kind of stuff.

Softwares I didn't know about, like ICEM Surf for exemple.
I'm going to check them.

and yes I know how to model in polygonal environment, I think I'm not bad and have some professional experience 😉
(attached some previous car model I did entirely in polygonal environment)
I need to give a CAD file of a model to a client for a specific need and we already tried in the pass working in the polygonal environment I know the best and then converting the file into STEP or IGES but the files was so big and complex due to the conversion, the manufacture couldn't use them.

So I'm trying to model it directly in CAD.
T-Spline in Fusion is a solution (that I'm not fan of) and I also have an other solution I'm testing now, which is modeling a low poly version in Maya (because it's quicker for me than T-Spline) and then bring it to Fusion, convert it to T-Spline to body and finish the model using Fusion model/patch environment.

[I_Forge_KC]

I agree that patch modeling is *not* the best way to do this stuff.

With that said, here is a tutorial series that models up a great looking model using patch methods (inside Fusion).

https://www.youtube.com/watch?v=wzaZTbnfszE

[kleinsylvain]

Hi, Yes I already watched this entire videos series and it's with these videos that I did my test I showed you in a post above as an attached image.

I don't understand how he doesn't have the non-continious surface issue that I have ... (visible seems beteween surfaces even when the base spline that they both use is a single continious line)..

But thanks 🙂
I'm looking towards Alias AutoStudio and a custom mix Maya-Fusion solution because I'll not have time to learn AutoStudio before working on this project ^^

[TrippyLighting · Accepted solution]

I have to admit that I have not watched that entire series, but I do have a good bit of experience in the patch environment. Enough to know that he most certainly does have those issues. There is really no way around it the way he designs this.

The patch tool, which he uses frequently is known in surfacing as a draped surface. It's basically draped over an opening like a table cloth and the way he uses it will most definitely have continuity problems. Does he ever check the curvature on the splines he creates ? These are fit point splines, which are 5-degree multi span splines. That's a No No in real vehicle modeling. Spans are to be avoided where possible. That's what the CV splines are for.

There is a reason that real cars are NOT designed using Fusion 360's patch environment. If you know what to look for that can also usually be seen in the renders. It can most definitely be seen if you check the curvature map.

You can do really neat industrial designs and product designs in Fusion 360 in the patch environment, but higher quality vehicles surfaces with control over reflections are not possible due to limitations in the geometric kernel, limitations that most of the mainstream CAD software packages have as they only allow up to 3 degree NURBS surfaces allowing a max of G2 continuity.

That is what also differentiates Alias and other pure surface modeling packages. For creating these surfaces you'l have a much more sophisticated tool set and geometric modeling kernel that is specialized for that sort of modeling.
It comes at a price inters of software licenses and skill development.

I can recommend the youtube tutorials from Handlebar 3D if that interests you. As I understand it he comes from a polygon modeling background and that can also be seen to a degree in his modeling approaches.

T-Splines create very heavy NURBS surfaces, meaning they have a very dense control point mesh. If you then split T-Spline generated NURBS surfaces with other splines preferably (NOT) fit-point splines as some tutorials suggest then your curvature these edges is trash, which often leads to other modeling problems, e.g. the inability to fillet corners.

[kleinsylvain]

thanks a lot for this reply full of informations and knowledge.

I'm actually watching the youtube channel you mentionned ! Just came accross it 🙂
Thanks