# Thread: "Revit can't do that....." series part 1

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## Re: "Revit can't do that....." series part 1

I once said "Give me a math formula and I will draw the shape in Revit"...
I am now biting the bullet and building an adaptive component that follows the formula in the initial post....

A bit unfare to challenge people to build it in two minutes though... it took me longer than that just to get my head around the variables!

Anyway, I'm on the case now, and hope to have it ready in a couple of hours... any idea of where to find the x,y coodinates of the nodes after relaxation??? it doesn't seem evident from the quoted paper... I suppose I will have a simplified version of the shape instead!

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## Re: "Revit can't do that....." series part 1

Here's my approach:
An Adaptive Component with 3 points: 2 origin points (to be able to deal with negative coordinates) and one for the projection of the desired node on the floor.

A second Mass Family hosts several instances of the Adaptive Component, and generates the surface using splines through points. If you need more precision in the surface, just need to add more control points, as wherever you land a point it will follow the surface formula.

Not too different to Zach's approach in this post:
http://buildz.blogspot.com/2010/03/l...-creation.html

just using the freaking complicated set of formulas in the beginning of this trail.

More interestingly, if you know what the "constants" that define the roof mean, you could start investigating variations and refine the shape, as this approach records the design intent as established in the geometric analysis.

I hope it clarifies one way in which Revit CAN do it! (I feel like Locke in Lost!)
Now I'm interested to know how others can follow the precision established in the geometry analysis in other software packages, beyond being able to draw a shape that somehow resembles the shape, but ignores the complexity of it... in two minutes?

Kind regards,
William.

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## Re: "Revit can't do that....." series part 1

Interesting discussion, and I'll throw in my 2 cents. I agree with opinions expressed, there is not one single ultimate software tool for projects of this nature and utilizing (and exchanging model data) a suite is likely necessary.

For studying the development of a surface like this in an alternative software such as Rhino or Grasshopper , you can find some relevant blog posts on my blog,

In the case of the Great Court, I'd read the same paper and generated a "mathematical" surface using the formula provided. Whilst this might take more than 2 minutes, it is a quick easy process to parametrically calculate this using NURBS. I was more interested in the process of smoother, continuous grid lying on the surface that was achieved by force-density mesh relaxation, and I've enabled tools within Rhino/Grasshopper to do this (demonstrated on the sample model of the Great Court Roof).

But this discussion is more focussed on how to define the original surface. Commonly project inputs will perhaps be less regular and (even more) difficult to define a mathematically formula to define the shape. Analytical form finding is more commonly used (prior to computers was done using physical models like hanging chains and soap film bubbles). Again I've developed (and am actively developing and improving) routines to do this type of calculation in Rhino/Grasshopper, primarily against uniform pressure like a balloon (not against a constant acceleration like gravity). Very useful for form finding domes with irregular perimeters or aspects such as ETFE cushions.

Whilst it's possible to use these tools through to detailed geometry setout, I've tried to focus on tools that are easy to use to test variation on competition and scheme ideas, with the option to pursue the form later in more specialist software (that generally requires technical knowledge and experience).

Other comments I picked up on where difficulties in transferring geometry from "rhino" to more advanced detailing programs such as Revit. Again this is a strong aspect I'm working on developing. I'm not sure if Revit now utilizes NURBS, but a "translation" would certainly explain different appearance or surfaces. At a component level, I've been developing neutral bim exchange using formats such as IFC to ease this exchange process with greater accuracy.

I am pursuing a direct Revit to Rhino/Grasshopper link, I'm interested to find any potential users to help prioritize the developments I'm pursuing. Please get in touch if you wish to learn more.

Cheers,

Jon

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## Re: "Revit can't do that....." series part 1

Very interesting.

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## Re: "Revit can't do that....." series part 1

Originally Posted by william.lcampo
Here's my approach:
An Adaptive Component with 3 points: 2 origin points (to be able to deal with negative coordinates) and one for the projection of the desired node on the floor.

A second Mass Family hosts several instances of the Adaptive Component, and generates the surface using splines through points.
Hey William, do you want to upload the actual project file for us to see this fancy family in the project environment?

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