Author: Felipe Rangel for FlyingArchitecture
Sometimes you need a 3d model of a specific object to use on a scene and you can’t allow yourself to replace it for something similar. It must be that unique one. Because your client requested it, because it is irreplaceable, because your stubbornness insists on using it, whatever the reason.
In this case, you have two options: either you model it yourself, or you search on the internet for it to download. And depending on the complexity of the object and the project’s deadline, it is much easier and quicker to just download it from somewhere. And downloading ready models is becoming much easier thanks to the ever expanding 3D databases on internet, like the FlyingArchitecture site and many others, with free or paid models.
That’s what I did when I decided to use the no. 14 chair from Thonet (1859) on a scene. I searched everywhere for a good model of it, I spent hours turning Google upside down to find it. And indeed I found some models of it, some great ones, nicely modeled and textured for sale in sites like Turbosquid, and some simplier ones for free, in these sites:
Of course I wasn’t willing to pay (and a lot) to obtain this model, and the free ones were fairly good actually, not perfect but decent. But I was looking for something excellent, a very Nice addition to my library, something that I could throw easily in any Project without looking cartoonish. The 14 would be a great addition, a truly passe-partout chair, an icon of design that is so simple and discret, yet so elegant and timeless.
I also found a 3D dwg file of it at Thonet’s official website. Today, in most of the big design companies websites, you can find 2D or 3D files of their products in a download section, where usually you need to register to have Access to it.
The 3D dwg model downloaded from Thonet’s website was a nightmare of meshes, with very deformed surfaces, useless for a good render, but with accurate dimensions and proportions.
At this point I had to make a decision of what to do to obtain a perfect model of a Thonet 14 chair. And I decided to refine the 3dwg model i got from Thonet, a good starting point.
I’m sorry to disappont a few of you, but I haven’t modeled it from zero, starting from a blueprint. I actually rebuilt everything from an existing model. Some may argue that the merit of the final model is not all mine, and I agree. But this is a very useful method to obtain a decent model starting from a poorer one that do not fulfill your needs, even if this method is laborious and longstanding. And is common to find models that would do great on a scene of yours. Only if they looked decent…
So in this tutorial I’ll go through all the steps to succesfully transform the 3d file of Thonet’s 14 chair into a great and clean model.
If you want to read the full topic at Flying architecture’s forum that originated this tutorial, click here to read the real time action and other curiosities.
Open the 3d dwg file of the Thonet 14 chair on AutoCAD. Rhinoceros 4 cannot recognize it and opens nothing.
When you have a 3d model you want to modify that Rhino does not recognize, open it on an appropriate program. Sometimes your archive is .dwg, .obj., .3ds, even .skp. Open it in 3ds Max or Autocad or whatever and export it as an extension that Rhino can recognise easily.
When we open the Thonet 14 3d dwg file, it says that the file was not originaly created in AutoCAD. This explains the bad meshes. Select everything in the file and explode it, and export the result as an Autocad 2004/LT2004 Drawing, the newest extension my Rhino 4 is willing to open.
Open the new file on Rhino 4.
Now let’s analyze what we should do with it.
This model is worth rebuilding because despite its deformed shape, its dimensions match exactly the declared dimensions by Thonet, and it is visually similar to the real chair on the brochures. Having no accurate blueprint of the chair, we should rely on the informations given by this 3d dwg.
The trickiest part to rebuild is the main back frame. It has an organic shape, with a sinuous form in the 3 axes and with different diameter sections. A true challenge. Mastering how to rebuild it is the hardest part of all the process, and accomplishing it Will help with the rest of the parts of the chair.
The commands of Rhino that come to one’s mind to rebuild it are Pipe, Sweep 1 Rail, Sweep 2 Rail or Loft. For some of these commands, you need the correct spline that defines the back form.
Trying to find the correct spline that defines the back, let’s pay attention to the model we now have in Rhino. If we look closely, we should realise that the mesh triangulation defines rings throughout the model. These rings give us sections of the model. The Center of each ring is a point that is cointained in the spline that defines the back. With these centers, we can create a curve with interpolate points that is the right back spline.
Explode the model and isolate a single portion of triangular meshes. With Osnap on and Project and STrack buttons off, create circles around the mesh rings with 3 points circles. After you obtained the circles, you can erase the used old meshes, they won’t be useful anymore.
Repeat this operation with half of the back rings and mirror them.
Do it again with the other bentwood parts. Let’s leave the seat untouched for now.