VOLUMETRIC Slicing 3D Object Using Dynamic Paint

In this post, I am going to show you a way to slice 3D geometry objects into multiple layers of images, using Dynamic Paint.

This is basically similar to what MRI scan does, but we will do it virtually inside Blender. If previous post was about how to import MRI data and render it out as 3D geometry, we will do the reverse of the process. Do read previous article to understand better what this is we are trying to do:
http://blendersushi.blogspot.com/2012/01/data-question-on-point-cloud-and-voxel.html

We will be using Suzanne, the monkey head for this example. The concept is simple, we just need to slice Suzanne into multiple layers, if I were to draw in the 3D diagram, it looks like below:

In Dynamic Paint term, the setup will be like this:

• 3D Geometry = Brush
• Slicer = Canvas

The 3D Geometry (monkey head) will act as a volumetric Brush so we set the Brush as Mesh Volume. 

The slicer object (Canvas) will simply be a flat plane. No need to create an array duplicates of plane like on the diagram above. This Canvas needs UV and enough number of grid resolution.

Here, you simply animate this single grid plane from the bottom boundary of 3D Geometry to the top boundary of 3D Geometry. Make sure you animate in Linear Curve, without acceleration. The number of slices will be equal to the number of frames.

One important part is to set the Canvas so that it only leaves Paint at a single frame at a time separately, we do not want accumulative effect like normal painting.

Once you bake out the Dynamic Paint, you will get some renders like below:

Dynamic Paint will bake image slices of 3D geometry.

And this is the render result of the Voxel Data above.

Working with Volumetric shader is a little tricky, it takes a bit of use to understand which parameter does what, I recommend you to watch video tutorial by Andrew Price on basic smoke. It will discuss volumetric shader and rendering:
http://www.blenderguru.com/videos/introduction-to-smoke-simulation

Below is a quick video tutorial:

VIDEO TUTORIAL ON 3D SLICING:

MULTIPLE GEOMETRY SLICING

You could have multiple overlapping 3D Geometry to be sliced, each as separate brush group, and then you combine them together back inside Blender Compositing. 

In fact, I recommend you to test this and see the result. This way, you could finally see the inner side of Suzanne and brain of Suzanne.

A quick example, say you like to create a 3D visualization of the Sun, and you want to show multiple layers to represent the interior of the Sun from most outer part to the core, you can certainly do it this way.

Slicing of volumetric.

OTHER USAGE OF 3D SLICES
What could be the other usages for this 3D slices, perhaps you can do 3D printing this way? Go ahead and find local 3D printing or local 3D laser cutter and then ask them to do slicing and you can have yourself a fancy looking model of your 3D model.

UPDATE 2012.10.10:
See also this cool MRI slices scan
http://www.buzzfeed.com/atmccann/7-food-mris-will-make-you-never-want-to-eat-again