Alias Surface SubD Modeling in 2020

[Autodesk_PX]

I believe for concept this might be very helpful.

Could you please direct me to some Tutorials how to use the new Tools in Alias?

Thank you very much

[rauscht]

Hi,

have you checked http://help.autodesk.com/view/ALIAS/2020/ENU/?guid=Alias_Subdiv_aboutsubdivisionmodeling_html already? It contains a bunch of descriptions, concepts and videos, and might be a good starting point for you.

Hth

Thomas

[Autodesk_PX]

Yes I did,

but there are merely axplanations how to propoerly combine the tools in order to receive a modell you can actually use. The context is left out. More or less its a basic description of the tool functions not how. For example there is a film about the "cage usage" how to get to the modell step by step in Alias would be rather helpful.

JWI

[rauscht]

Hi,

unfortunately there are no dedicated Alias tutorials describing step-by-step how to create a specific model. Mainly because we feel that there are thousands of such videos out there dealing with the Subdivision modeling paradigm and principles (check you tube for those and you will see what I am talking about).

Instead we focused on creating material that describes the Alias specifics, like our hybrid modeling approach (all the NURBS tools may operate on Subdivision bodies, which makes them first class members of Alias). Video https://www.youtube.com/watch?v=7PodaFhOuxA falls into that category also.

Hth

Thomas

[colorzeppelin]

Using Alias Surface too. It is not very clear if the new Subdivision modeling features are the same in Alias Surface and Alias Concept because of this article: https://knowledge.autodesk.com/support/alias-products/learn-explore/caas/simplecontent/content/alias...

"The sub-divisional feature set in Alias SpeedForm, and the design tools in Alias Design are available in Alias Concept."

For example the wheel-arch creation tool.

[Autodesk_PX]

I have tested it now quite a bit, there are limitations I feel need to be improved.

I would rather create a basic shape via Lines and create the surface/Volume by blending between the lines. A little like you would start modelling interior / exterior Models with Maya.

With Alias Solution I more or less have to start with a basic shape (Cylinder, Quader, Surface) and modify, this seems not to correspond to the desire to have control over the shape by precisely add geometry just where you need it. 

Did I miss such a possibility in the provided toolset ?

JWI

Are there tools such as 

[shinji-pons]

You can use Subdiv Extrude on degree 1 curves

[Autodesk_PX]

But this does not apply to curve networks?

JWI

[shinji-pons]

To my knowledge, no. Even if the curves in the curve network were of degree one, there would still be non-trivial problems in situations where the number of edges is not the same of both pairs of curves.

[Autodesk_PX]

I found out that you can actually use new CV Curve with curve Degree set to 1 in uniform mode will provide almost the same result as in Maya. you can at least extend the result with Sub D Extend.

Works well Though

[shinji-pons]

Yes any degree 1 curve will work even circles which you can detach to make things like perfect wheel arches

[pascal.fessl]

Not a tutorial, but helpful:

https://www.youtube.com/watch?v=Bqs68cSg0w8&feature=youtu.be

[brian.osborn]

Hi Shinji, I agree with the originator of this thread, would it not be possible to have an add vertex tool ( bit like Maya Quad draw) where you can free form or snap additional vertex to grid, other geometry or even a canvas plane. At present  you have to extend/extrude, then pick the resultant vertex to either snap to something or use the align to curve, then slide them along, it works, but its clunky compared with quad draw. This is available in speedform workflow too ( as a freeform quad creation tool, but without a good snapping ability) and works well.

[shinji-pons]

Hi Brian, 

In the publicly available software, the only way that allow free-ish positioning of SubD vertices is with the cut tool that will put CVs at a specified position along an existing edge.

That being said, I am sure that Autodesk have heard of the Quad Draw request and perhaps are working on a solution as we speak.

[Anonymous]

Why is impossible to convert a SubD into a NURBS and then, use it in other applications once saved in IGES or ACIS?

Many years ago Maya converted polygons into subD and then into a Nurbs. Why is it impossible today?

Thanks

Filippo

[shinji-pons]

Hi Filippo,

It is completely possible to convert SubDs to NURBS in Alias. I don’t have Alias open in front me right now but if you look inside the Surfaces tab of the Palette, you will find the Surfaces from Subdiv tool. 

[BarryKimball]

For clarity...subd's in Alias ARE nurbs...there is no conversion necessary...

 In Alias if you export a subd as IGES or STEP the limit surfaces of the subd are exported...not the cage (subd) that controls the shape of the subd.  IGES and STEP do not support subd geometry. As Shinji mentioned there is a tool to extract the limit surfaces from a subd...so you have a copy not attacted or controlled by the subd cage...Surfaces->Surface from Subdiv. Alternatively you can selact all the limit surfaces and execute a copy/paste...the limit surfaces are duplicated and extracted from the subd.

[brian.osborn]

Hi Barry, thanks for this, but just a note that although logically copy paste should work, we have experienced some issues that some surfaces will not copy paste, and some become strangely corrupted _ they look like degree 1 multi patches - the Surface to SubDiv tool seems more reliable. ( although you'll probably tell me that its doing the same operation ......)

Also duplicating SubD objects/surfaces across centreline seems to have its own set of niggles regarding shaders.

Regards Brian

[BarryKimball]

If copy/paste is not working...we need a reproduce-able data set...I have not seen or experienced that before. The limit surfaces are already surfaces...there is absolutely no conversion. You can see the exact limit surface definition if you select an individual limit surface and open the info window and check the degree or the control panel and view the degree. If you copy and paste that limit surface and the values change in the control panel, that is a reproducible data case that we would really like to have. I will check into the ability of subds to generate degree 1 limit surfaces,...but I do not believe that is at all possible...limit surfaces generated by the subd are either degree 3-1 span in both direction or in the case of ngons the surfaces will always be degree 7+multi spans. The layer symmetry is not correctly applying shaders to the created geometry, I have submitted this as a bug. In the meantime you can use the duplicate mirror tool on the subd node (select the subd via object selection (not as a component/limit surfaces))

[brian.osborn]

Hi Barry, thanks for this, Ive just had a quick look at a couple of models that I thought were showing this issue - on closer inspection its just a weird graphics issue, when we copy and paste the underlying nurbs patches, some appear with Boxmode on, and some don't, its then impossible to turn the boxmode off on some patches without filing up and re-starting, so just a bit of a pain really.

By the way, isn't there some way that Alias would recognise SubD entities and only apply box mode to them? It's a bit annoying when you have heavy nurbs parts such as alloy wheels and tyre treads that shade to box mode...