T-Splines
T-Splines

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7/09 Creating stunning jewelry designs with T-Splines View
5/07 How to approach modeling with T-Splines View
3/07 Carl Bass reintroduces T-Splines for Rhino View
6/21 Transitioning from NURBS to T-Splines View
12/07 Footwear modeling with T-Splines 3.3 for Rhino View
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10/28 How T-Splines changed my aproach to making jewelry in CAD View
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Edge representation

A support and feedback forum for Autodesk T-Splines Plug-in for Rhino users.

Edge representation

Postby Andress S » Wed Jan 11, 2017 7:51 am

Hi everyone!

Can someone explain to me what determines the change in the edge position when toggling smooth/box modes.
Capture.PNG

Capture1.PNG

Should I just ignore those big differences or is there a way to fix this?

Many thanks!
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Re: Edge representation

Postby JSantocono » Wed Jan 11, 2017 11:02 am

Hi Andress.

The change in the edge position is determinate by several factors... Most important are the position of the adjacent edges, and the tension of the surface (knot value). A most tense surface, more difference on the position.
By seeing your surface it seems that it has a lot of tension. You can "relax" it by using the tsMakeUniform command. Try it out and you will notice a change in the difference between the control point (BoxMode position) and the actual edge (SmoothMode position).

I would say that what it counts is the SmoothMode surface position. But of course that having less difference between both modes is always better and make modeling with T-Splines more controllable.

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Re: Edge representation

Postby Andress S » Wed Jan 11, 2017 4:16 pm

JSantocono wrote:Hi Andress.

The change in the edge position is determinate by several factors... Most important are the position of the adjacent edges, and the tension of the surface (knot value).


Juan,

thanks for a quick reply!
Is there a way to control a knot value or it depends on nearby star and t-points?
I deleted some of the edges and simplified the model which seemed to relieve the tension on some parts of the model. tsMakeUniform didn't help as some t-splines were not able to be uniformized.
I still get weird crease on the bottom of the model.
CaptureJ.PNG

mouse.3dm
(1.7 MiB) Downloaded 125 times
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Re: Edge representation

Postby JSantocono » Thu Jan 12, 2017 7:43 am

Hi Andress.

There is not a practical way to control the knot value. It depends on how you made the surface, where and how you added geometry. I would say dont worry about the knot value, just use tsMakeUniform often!

Your model have weird stuff because of the T-Points and how you are using them. I recommend not to use T-Points indiscriminate. There are some rules to use T-Points and StarPoints to avoid non-wanted geometry and weir shapes.
You can check it on the T-Splines manual, but as a general rule I can say that TPoints and StarPoints dont get well together. T-Points have to be more than two faces away from StarPoints in order to work correctly and in a predictive manner. If T-Points are closer than this you will get "hidden geometry". The T-Point will extend until you it gets out of this area of influence. You can use tsStandarize to make this hidden geometry visible.
You have to options here...
1-Convert all T-Points on your model to STarPoints using the tsLayout command :tsLayout:
This will avoid the funky geometry, but with a cost. More StarPoints means a slower computational model and some non-wanted surface shape.
2-Try to avoid T-Points as much as you can. Just use them when you are sure they are on an isolated part of the model.
I would recommend this solution, specially in your model where you dont have too much faces and have a lot of StarPoints. This means that a T-Point on your model can be extended all arounf the surface just trying to get out of the area of influence... You wont be able to control the shape you are looking for.

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Re: Edge representation

Postby Andress S » Sat Jan 14, 2017 4:05 am

I see that Kyle Houchens in Modeling a car with T-splines webinar does not really care too much about where to put a t-point. He's got some of them placed right on the same edge as the star point and nothing funky happens.
Cap_Car.PNG

Does this have something with the the version of the T-splines he's using or the mesh settings?
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Re: Edge representation

Postby Andress S » Wed Jan 18, 2017 2:29 pm

Thanks Juan for explanation, I have read t-splines manual previously but I still don't fully understand some behaviors of t-splines. All I know is that one should avoid non-4sided faces and that t-points should be 2 faces away from star points. I would like to know if there is some more specific info on how to manage multiple-sided faces, multi-valent star points and when are 3-sided faces allowed?

Could you please take one quick look at my model and suggest how to close the gap as I have not managed to do it properly using :tsBridge: and :tsMerge:.

gap.PNG
gap.PNG (133.09 KiB) Viewed 6372 times


I regularly get seashell at same vertex when closing and after that model won't convert to smooth mode.

gap1.PNG
gap1.PNG (47.41 KiB) Viewed 6372 times
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Re: Edge representation

Postby laurentheid » Sat Jan 28, 2017 6:58 am

Did you click on the seashells until they're converted and disappear?
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Re: Edge representation

Postby JSantocono » Mon Jan 30, 2017 7:07 am

Yes, Seashells can be avoid by clicking and converting into a StarPoint.

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