The Linkage Computer

This is my final project for 6.849: Geometric Folding Algorithms by Prof. Erik Demaine, the happiest genius of the world.

In fact I prefer to call it ‘the origami class’, which sounds more obscure to my friends. And complex, curving origami was indeed what I expected myself to do at the beginning. Well, the field turned out to be much broader and even more interesting (absolutely an understatement).

Anyway one day we were introduced to Kemp’s Universality Theorem, which says ‘there is a linkage that signs your name’. In proving that Kemp invented 3 gadgets: multiplicator, additor and translator, which perform arithmetic operations on any input angle. Then the idea came to me that if we can design gadgets that perform boolean operations, we can build a computer from just hinged bars.

I always had a thing for mechanical computers. The article that talks about the rope-and-pulley computer by Apraphulians was my all-time favorite of Scientific Americans. This project might be a little nerdy, but who knows — mechanical logic gates do make sense on nanoscale and in extreme environments like outer space.

Here is how I represent bits with bars. Note that each bar is constrained to rotate in half plane so I gain a nice ‘black box’ feature where the implementation of one gadget does not disrupt the rest of the machine.

Here are the logic gates: translator (moving a logic state across space), invertor (X -> not X), AND gate / OR gate (they are mirrored image of each other). Watch the video to see how they work.

Using the above gadgets I will be able to build a full adder (A, B, Cin as input and S, Cout as output). I’ve made a simple simulation with Processing. Click the input bars to switch states:

The models I constructed use wood sticks and rivets. I also proposed another way of building the gadgets — cut and fold them from one piece of flat material. It would be awesome to cut a whole mechanical computer out of one piece of thin metal, roll it and take it with you to a place with no electricity and do some crazy computation.

I’ll be continuing this project during the winter break. Many thanks to Erik & Martin Demaine and Tomohiro Tachi. It’s been so cool!

Tools used: AutoCAD, Processing

The Slow Glass I

This is a project for a Media Lab class: New Paradigms for Human-Computer Interaction by Pattie Maes and Hiroshi Ishii. Slow glass was imagined by Bob Shaw in the science-fiction story The Light of other Days. Light travels very slowly in this material so that it takes months or even years for people to see what had been on the other side.

We consider the slow glass as an architectural element that provides a window into another space/time. It changes people’s perception of the surroundings. We tried to make an elegant implementation for the concept. The screen is located in the lobby of the new Media Lab building. One camera captures sequential images of the lobby and tracks the coordinates of people using background subtraction. Another set of cameras on the back of the screen records a panorama of the lobby. Video is played back, a few hours later, according to the relative positioning between a person and the screen. From a user’s perspective, the screen is like transparent, only that through it he sees the past.

The tracking system, powered by OpenCV:

A diagram of perspective simulation:

A video of the concept and the first prototype that we presented in the class review. We are currently working on making it a permanent installation in the Media Lab building:

Tools used: Open Frameworks, OpenCV, iMovie
Collaborator: Polychronis Ypodimatopoulos, Daniel Rosenburg

Map of Paris: Visualizing Urban Transportation

Update: If you are interested in isochronic maps, I have more detailed explaination of the process in my graduate thesis Seeing Differently: Cartography for Subjective Maps Based on Dynamic Urban Data, and the source code (Processing) is on GitHub.

What is your mental map of a city? I bet it’s not measured in miles. This project is part of my work in the SENSEable City’s workshop this semester. In these distorted maps of Paris, the distance between a spot and the city center is not proportional to their geographical distance, but the cost taken to get there.

Standard map vs. driving time map of Paris: the city center expands from congestion, and the edge is denser.

Comparing the isochronic map of Paris under different transportation modes: (unit: minutes, click to zoom in)

Think driving is better? However, if we map the city using carbon footprint as distance: (unit: kg CO2, click to zoom in)

In the workshop I proposed an alternative to Google Maps on smartphone map services. I call it an isogreenic map. This would have a psychological influence on the user when he decides which transportation makes the trip easier:

Made with Processing.
Vector map:
Connection data: Google Directions,

A demo video that shows how the transformation works:

Softly Rigid

This is for 4.553: Digital Fabrication by Dennis Shelden. The assignment asks us to explore the process from digital to physical representation, and reverse. It eventually became an interesting experiment for me to push the boundary of materials.

I was inspired by the shape of tea bag — through folding, soft material such as plain paper might gain strength and form a designated shape. I wrote a Rhinoscript that translates any free formed, double curvature surface into print patterns that can be cut out and folded.

Of course, not all surface can be perfectly unrolled to the plane. However, I can guarantee that the curvature at each joint is correct. The original surface:

The unrolled unit shapes generated by the script:

A physical test model:

Tools used: Rhino