Future of 3D printing – part 3

In my previous posts on the future of 3D printing I talked about the impact on manufacturing and development of the industry. In this post I am going to talk about the next steps of 3D printing as a technology.

Digital materials
I want to talk about digital materials first. This technology is researched by Hod Lipson from Cornell University. The theory is to assemble parts by stacking extremely small grains of materials and cure them. It is inspired by how biology creates complex structures like DNA or proteins.

Each grain is put on a grid next to another grain based on a digital model. It allows for mixing materials by selecting the appropriate grains from a bucket. This allows for a large variety of materials to be used to build the part something currently technologies cannot do. But it becomes extra interesting when grains of different materials are mixed in a specific pattern. It allows for the creation of completely new materials with very unique properties which do not exist today.

Another reason why I am bullish on this technology is that it is very digital instead of the current 3D technologies which are more analog. Going from digital to digital gives much more control on the output, allows for more manipulation of the 3D models and is easier to automate reliably. Just look at television which went from completely analog to fully digital today. But the same applies for music players (MP3 players) or computer storage (SSD).
Please also read the excellent web page about digital materials at Cornell

Voxelization of 3D models
The other major step I see is the voxelization of 3D models. It is actually related to digital materials. Hod actually calls the grains voxel but I refrained from using that term in that part of post to avoid any confusion.

With voxelization of input I mean that the input is changed from polygons to voxels. 3D models today are mostly described in files using polygons. These polygons describe the contour or shape of the 3D model in a similar way vectors describe drawings. The benefits for describing 3D models are that the current computer technology can easily handle them. The required file size and memory in a computer is small in comparison to voxels. The problem is with resolution. Polygons are only an approximation of the contour of a shape. Very high details require huge amounts of polygons and are still only an approximation of the actual desired shape. It does not describe how a 3D model actually is build since it is only focus on contours or shapes. When multiple material printing becomes more prevalent it becomes cumbersome to keep on using polygon based files.

The solution is to use voxels. Voxels are 3D pixels and can be compared to pixels of a photograph – but then with 3 coordinates instead of 2. The 3D model is described as discrete blocks. Using that model it is possible to create much more complex 3D models than with polygons and it enables designers to actually specify how a 3D model is build physically.

Another benefit of voxel-based 3D models is that they are easier to reliably manipulate and process by computer software. You can compare it to processing of photos using Photoshop.
The problem with voxels is that they require 100x to 1000x times more data to describe a model. With current computer technology this is not very practical. Luckily Moore’s law comes to the rescue – which states computing power will double every 18 months.

To me both digital materials and voxelization of input will lead to major breakthroughs in 3D printing. Both technologies are still very much in research. Voxelized 3D models are using in some very very high end applications like MRI scanners. It is in my mind also closer to reality than digital materials.

 

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  • Justin Solomon

    Great article. I’m new to the 3D printing game. I work in the field of medical imaging (CT). Myself and others in my lab are starting to use 3D printing to create test objects to image on our CT scanners. Using the polygon paradigm is a huge pain and we would greatly benefit from a voxel-based input. Especially with multi-material printing. Anyways, since this was written several years ago, what has changed since then? What is the current state of voxelized inputs to 3D printers?

    • http://robert.schouwenburg.com/ Robert Schouwenburg

      Thanks Justin! I can imagine that is a pain to go from CT to polygons. Unfortunately I have not seen much progress in this area. Maybe there is some research group working on it, but I have not seen anything promising yet.

      If you find something, I would love to hear about it!

      • Bubba Kittee

        Techniques for converting voxels to polygon meshes are well-known. The “Marching Cubes” algorithm, for example, is so old that the patent has expired. The big problem with voxel data is that there’s no way to directly send it to a printer (as far as I know).

        • http://robert.schouwenburg.com/ Robert Schouwenburg

          True! But I was actually referring to the problem that they have a huge amount of polygons after conversion. It makes it a pain.

          It would be great if you could go from voxels directly to “slice” files. It should be possible technically.