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Guest designfreak

Alias & Bi-rail Issue

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Guest designfreak

Hey all,

 

I'm a newbie to Alias Studiotools and would appreciate some guidance. Everytime I try to use the Rail/Bi-Rail function and select the appropriate generation curves and rails, Alias does not want to build the surface and gives me the following error in the promptline history:

 

"Combined rail curves exceed Max Surf Spans tolerance."

 

I am trying to add the sides to the two surfaces. I attached a screenshot.

 

Any suggestions on what may be causing this and how to fix it.

 

Thanks

--df

post-3775-1259449230.jpg

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You're trying to rail something that doesn't want to form a planar surface. To form the edges you should probably skin between your two pink surfaces. It will form a much cleaner surface than trying to rail 3 curves along a compound curve.

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Guest tekbot

Cyberdemon is right, your current set-up is not the optimal solution.

 

it almost looks like you are trying to get a round edge with your profile curves. (are you?) it would be better to make the edge sharp first then round or "surface fillet" the edge. remember to build primary shapes first, then blend them.

 

another option that you could try is bi-rail a single profile along 2 rails. switch to the advance tab and switch the transform method to "non-prop scale". this will keep your profile from bulging when the distance between the rails changes.

 

 

WHY THE ERROR...

the edges you are building from are trimmed edges from a curve on surface (COS). a COS is always 3rd degree and adds spans to achieve the shape. when ever you build a rail or square, you have to turn on rebuild for atleast one of the edges if not both. i could give you more technical reasoning... but this basic rule of thumb is good enough for newbies.

 

 

TO FORCE IT TO BUILD...

if clicking the rebuild does work then you have hit the max span limit for your construction tolerances. this is default at 100. you can set it higher, but if you need more than you are definitely trying to do too much with your patch layout.

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Guest tekbot

Here are some examples of other ways to approach this. there is a ZIP file of the WIRE's. I left construction history on so you can "Query Edit" the surfs.

 

to create the plan view of the shape, build separate curves for the corner shapes. this will help keep it light and make it easier to change the shape if needed.

 

a few methods...

 

1. (FAST) use "Profile Blend" to do the sides with a single profile. select "Chain select" to select all edges that are atleast tangent. this is basically like a bi-rail that you can choose multiple rails at once. very cool.

 

2. (GOOD) project curves onto top and bottom shape. since there is 8 segments each skin is light weight. if you want to get more shape on the sides. select the middle hulls of the skin and move them normal to the surface(CV/Hull move in control panel).

 

3. (MOSTLY SINGLE SPAN) build natural boundary surfaces for the sides. an easy way to do this to project curves instead of COS (option found in the project tool). choose match original. then skin or birail the sides and use surface fillet to intersect, trim, and fillet all in one move.

 

post-14660-1259946766.png

soap_models.zip

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