Repeat and Divide Prt II: Unfolding


Still a bit experimental, and it’s only for planar panels but I feel like I’m finally getting a reasonable automated surface unfolder using Repeat/Divide. And once you have a rationalized surface (also look here) and the panel itself, the creation of accurate unfolded geometry is ridiculously easy.

The last real problem was figuring out a sensible way to control the layout of the unfolded panels.


It leverages the same panel shown in this post on the reporter pattern:


Where the green surface is essentially a projection of the yellow panel geometry. The yellow panel is created in point 1-4, measures its self, then redraws another quadrilateral based on these measurements on the workplane of point 5 (point 6 isn’t used). A single instance of the panel is placed on 2 divided surfaces, points 1-4 on your base surface, 5 and 6 on a surface to structure your layout.  Select the component and hit Repeat.




Ready for layout on a sheet for annotation.

Repeat and Divide Prt II: Unfolding

Not everything that is needed for fabrication certainly,  but would be interested to hear any feedback. It works for flats, but it doesn’t have real geometry for compound miters. That can be recorded in tabular format, if not made graphical.

For whole flat surfaces that just have plain extruded panels without compound miters, you could do complete shop-drawing-ready unfolds





Download the panel and sample datasets from here.



Paper Models


Hey look!  Real stuff! 


Made from fake stuff!


User Question:  Can Revit/Vasari unfold my geometry so that I can make a paper study model? 

I get this question all the time and the answer is a resounding “No!  Tough beans!”

However, I do have a simple formula for solving this problem: 

Revit Panels + Pepakura = Awesome

Pepakura is a hobby papercraft software that unfolds and tabs your 3d data.  Just import any compatible file (obj, dxf, mqo, 3ds, lwo, stl, kml, kmz, dae) hit the “unfold” button and hope for the best.  They have a free download that allows you to experiment pretty heavily before deciding to invest the $38 for a fully registered product (that can save and export files).

With the above model I had some trial and error getting to this relatively simple unfold2012-04-10_2136

This afternoon I got out my glue and scissors and assembled it in about 15 minutes:



I am sure that you, dear reader, with your patience and exacto knife, can do better.

However, before exporting your form, you need to do some prep. 2012-05-15_2041

If you just export the full smooth model to stl (Vasari has a built in stl export) and unfold, it is just a mess of hairy triangles.  STL is a triangulated mesh format, and will tessellate the hell out of your model.



However after panelizing with a simple rectangular panel, you get this from an STL. 


A couple of things to note on this.  My form is a scale translation surface, which means it can be panelized entirely with planar quadrilaterals. If I just panelized any old freeform surface, I would be exporting lots and lots of doubly curved surfaces, which means lots of triangles for an stl file.

So a slight tweak of this scale translation surface from this 2012-05-15_2050

where my lofted profiles are parallel


To this,


where my profiles follow the path.


This small change will result in non-planar faces. In Pepakura your unfold will be like this:


WTF?  Well, each one of these little panels from your model is in fact a crazy mess of triangles trying to cover your doubly curved panel surface.

2012-05-15_2135 Frankly, it’s a wonder that Pepakura makes as much sense of it as it does. This is also a pretty good predictor of the chaos that trying to actually build this form will cause with your contractor, owner, finances, and sanity.  Scale Translation is your friend, trust me.

An alternative is to panelize in Vasari with triangles.  Triangles, the always capable, generalizable, cover-any-surface–planar solution, can be controlled by adjusting the divided surface resolution to your taste, then exported.



I’m sure that there are other, more professional options for this.  However, to do this exercise I spent a grand total of  $0 (Vasari at $0.00 per seat, and Pepakura trial at a similar figure).  If it works for you, splurge for the $38 registration fee. 


Repeat and Divide Prt I: curved panels


Buildings are not monolithic things . . . if there is one thing you can say about all buildings (cave dwellers and freaky 1970’s Gunnite structures aside) it is that they are made of many, many tiny parts all glommed together.  In one way or another, our built environment is made of repeated elements in space.

Given this, why doesn’t our BIM have a unified method to array/repeat/distribute/etc elements in space?!?!?!? 

Well, the Repeat and Divide functionality that is new in Revit 2013 is not the Great Unified Solution, but it is pretty damn awesome anyway. 

User Question:  I have a mullion that needs to follow the curvature of my form.  Both curtain system and curtain panel by pattern functionality facet my form.  How can I get back to smooth curvalicious goodness?


With a few exceptions, the Divided Surface, Curtain Panel by Pattern, and Curtain System functionalities reduce smooth surfaces to facetted ones.  While this is often exactly what people might want, sometimes you might want to subdivide a surface into smoothly curving parts. 


This video walks through a couple varieties of smooth paneling options

Curved Panels

Download the example files from here.