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Hi all

Trying to find best method of creating shade sails, generally four points at different heights. With curvature between points.

Coming from Revit background had a few options using using floor or roof and adding heights at corners (this gave a fairly good outcome)

 

using 2021 and I'm a newbie at vectorworks, any help much appreciated

 

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There are a few NURBS Face options in VW.

 

Either create a simple Rectangle in plan and convert to NURBS Face,

to pull your edges to the desired Z offsets and move it in place in Z height.

 

or create Arcs between the base points and finally create a NURBS Face from

2 Profiles and 2 Paths. there are a lot of older NURBS tutorial Vidoes on VW's

youtube channel or Help files and VW university will also help.

 

 

If you are more on the sculpting side, you can also convert a Rectangle to

a SubDivision object and use the SubD Tools to manipulate the corner heights.

 

There are maybe even more viable ways in VW to do that.

 

 

Also there may be even already some ready to use Symbol Resources in

VW Libraries in Resource Manager ...

Edited by zoomer
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@cherub By the way, Welcome the the Forum!

 

I know a couple ways to show the area of the sail.  There may others.

1. Select the sail. Model menu>Volumetric Properties.  The data includes area, volume, center of mass.

Opt to Place on Drawing. Click on drawing. Creates a group.  Ungroup to reveal a text box.

 

2.  Select the sail.  Give it a name (bottom of OIP), eg Shade 1.  Assign the sail to a new Class, eg Shades. Create a worksheet, eg 2 rows, 2 columns.

Database header row criteria should be Layer is Design Layer 1 (or appropriate) and Class is Shades. Column A function =Name, Column B function =SurfaceArea.  (Note: =Area function does not recognize the NURBS surface for some reason, so use SurfaceArea).

 

Note:  If the object is a NURBS surface (no thickness), the Volumetric Properties and Worksheet described above will return area of one side of the surface, similar to area of a closed 2d object.  If the NURBS is subsequently shelled or otherwise given thickness, the VProp and Worksheet will report the combined area of the top face, all the edges, and the bottom face.

 

 

I wonder if a Record/Data Tag can be contrived to show the area? Anyone?

 

-B

Edited by Benson Shaw
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You should be able to isolate the shades in worksheet data. Put them on a separate design layer, or create a new class just for the shades, and give each shade a name. Then use appropriate criteria

 

You likely figured this already, but note that the volumetric property is not smart.  It does not update. You need to delete and create a new one if the shade is changed

Edited by Benson Shaw
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  • 6 months later...
On 4/10/2021 at 12:59 AM, Benson Shaw said:

Here is quick NURBS method:

Your sail maker and engineer may have guidance for how much z sag will be produced in the center, and xyz sags of the edges.

More sag means less tension and, therefore, less structure needed to support wind/snow loads.

 

Several more ways and refinements to do this with NURBS, Interpolated Surfaces, Sub D.

Post if more help needed.

 

-B

 

 

image.png

 

NURBS Shade.vwx 352.08 kB · 5 downloads

Help please! I would like to model flat sails, possibly with slight curves cut into the sides, and  want to be able to have that as a flat pattern for the fabricator. I also want manipulate the sails in 3D without distorting it, so I can see what it would do if twisted or bowed etc. Some of the sails may need to be more than 3 or 4 sides...  How do I accomplish this in VW? .... The reverse would be to model something I like, then flatten or unfold the sails to get the patterns, but don't that is possible in VW? any tips? thanks in advance- JC

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On 4/9/2021 at 1:15 PM, zoomer said:

There are a few NURBS Face options in VW.

 

Either create a simple Rectangle in plan and convert to NURBS Face,

to pull your edges to the desired Z offsets and move it in place in Z height.

 

or create Arcs between the base points and finally create a NURBS Face from

2 Profiles and 2 Paths. there are a lot of older NURBS tutorial Vidoes on VW's

youtube channel or Help files and VW university will also help.

 

 

If you are more on the sculpting side, you can also convert a Rectangle to

a SubDivision object and use the SubD Tools to manipulate the corner heights.

 

There are maybe even more viable ways in VW to do that.

 

 

Also there may be even already some ready to use Symbol Resources in

VW Libraries in Resource Manager ...

zoomer- is it possible to not distort the size/shape/volume/area of the nurbs surface when moving it around? How do I "lock" the shape? I want to be able to start with a flat material so I can draft it later for the fabricator. 

 

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Oh, I don't think that is possible (?)

Someone else may chime in.

 

I think it would be possible to create a suitable NURBS shape and finally

Model > 3D Power pack > "Unfold Surface" to draw itfor the fabricator.

 

But I also think it will be quite difficult as I expect the Fabric to expand in some

way when under tensile force, which should be precalculated (?) and finally

excluded from the shape.

I think fabricators should have better tools for this (?)

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thanks for that  - I just tried "unfold surface" on one of my objects, but didn't work as it was a compound curve ...but "tool tip" says it would work on a surface modified in one dimension, such as the surface of a cylinder. 

 

would be better if I could start with a flat shape and move it around without distorting, but you are correct - there would be so stretching for sure...I would have to approximate, and the fabricator would need to factor that in. I would like to do a model that is "build-able" and not one that is misleading. Its a conundrum. 

 

 

Edited by Judy Cosgrove
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I think there is special Software for this.

And that it is far above VW's pay grade.

 

I think in reality it works by a designer demanding THIS and the manufacturers

will calculate and offer a solution and production details ....

Or maybe organized and surveilled by a structural engineer (?)

Edited by zoomer
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  • 5 months later...

Thank you all for this excellent thread. Benson I followed your workflow successfully. Thank you again for such clarity. I am posting here to offer a small point:-

Comand :- Model>3D Powerpack>Create Surface From Curves did not always work.....why? I think because the directions of the nurb curves were not all clockwise. As soon as I changed two opposing directions to follow one another and so all curves had the same direction then the comand worked.

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@thinkingpencil glad you made it work. As you discovered with the Surface from Curves command, NURBS operations can be finicky! Direction, degree, etc.  In Help, there is some interesting discussion of the Surface from Curves algorithm - eg number of crossings vs number of area sections.

 

It would be great if a sailmaker or other with experience related to tent structures and suspended sun sails would add some comment or guidance about sag, stretch etc. 
 

And, I wish theses vwx NURBS tools and commands would get some improvements in the anual vwx version upgrade. Especially fix the faceting evident on many NURBS generated edges. 
 

-B

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...Yes a big subject. Thank you again. I am looking forward to learning more. And will check out those references. Meanwhile I remember a fellow student of architecture whose final thesis featured tent structures like the German engineer Frei Otto's. He learned some basic rules of design by studying Otto's 1972  Munich Olympic stadium.

I remember those rules were all about sag, curvature etc etc

 

I am meeting him soon and will pass back any advice on them.

 

PS the video at the link is not HD for sure! But then in the seventies the fax machine was yet to be invented...

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  • Vectorworks, Inc Employee

Hi All,

 

Here's a little NURBS model video with a quick data tag that pulls the area...  If I were modeling sails, I'd model a close approximation of what I wanted including the basic dimensions, etc and then let the sailmaker work out the exact details depending on the chosen material...Sails have come a LONG way from the old canvas days...trust me...

 

And yes, the Unfold command will only work on a developable surface...(think of bending a piece of paper without creasing it)

 

Wes

 

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11 hours ago, thinkingpencil said:

Thank you all for this excellent thread. Benson I followed your workflow successfully. Thank you again for such clarity. I am posting here to offer a small point:-

Comand :- Model>3D Powerpack>Create Surface From Curves did not always work.....why? I think because the directions of the nurb curves were not all clockwise. As soon as I changed two opposing directions to follow one another and so all curves had the same direction then the comand worked.

@thinkingpencilGreat you reiterated the Nurbs direction issue. has bitten me more than once.

  • Like 2
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