Tuesday, December 15, 2015

3D Printed Cytoskeleton Figure Sculpt

I've been searching for an interesting geometric variation to the figure forms I've been sculpting. I wanted to do quick sculpts from live models but use computational geometry to convert them into spatially interesting, geometric forms.

The last sculpt I did I kept very simple. I wanted the proportions correct, but only the basic form. For example barely an indication of fingers or toes. Same for the ears and face. My original ZBrush sculpt is shown below:

(The ZBrush sculpting process is described in this post).

Using ZBrush's Decimation Master and Rhino's Grasshopper I was able to get the geometric form variation I was after and 3D print the result. Below are details of the process.

The first step was to use Decimation Master to greatly reduce the face count. The original sculpt had 1.5 million faces.

Here's the sculpt after reducing it down to only 1,100 triangular faces.

The next step was to use a Grasshopper plug-in called Cytoskeleton. This is a wireframe thickening tool written by Daniel Piker. It will take a triangle mesh and turn every edge of the mesh into a solid suitable for 3D printing. If you want to try this all the Gha and Dlls you need are zipped here. Put them in your Grasshopper Components Folder (in Grasshopper do File > Special Folders > Components Folder).

The Grasshopper definition is super simple:

You specify a mesh, a radius for the thickening, and a Boolean to indicate if you want to use the original mesh or its dual.

The dual of a triangle is constructed by taking its center point (shown in green) and running a line through the midpoint of each edge (shown in black). Connect the ends of these lines with the corners of the triangle. This results in a hexagon (shown in blue). This hexagon is the dual of the triangle.

This is done for every triangle in the mesh. This technique was used for this form.

Cytoskeleton generates a water-tight 3D mesh, ready to print. Here you can see the dual cytoskeleton compared to a mirrored version of the original, decimated mesh. 

I used the online 3D printing service Shapeways to print this file. To keep the cost down I made it 10" long. I used their "Strong & Flexible" plastic material. It came out really well.

Here's another variation using a different technique: Tesselated Voronoi Figure Sculpt.

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