Week 7: Midterm Project


Trapped Souls / Jiwon Shin + Becca Moore – 2018

Jiwon Shin and I collaborated for our Midterm Project in Danny Rozin’s Physical Computing class. We created a box of “trapped souls” that need your help escaping! Move the box around to help the souls find their way back into the world. Once you’ve released one, another one will appear that needs your help as well.

See our original project proposal here as well as a progress checkin.  See Jiwon’s awesome post for more extensive process documentation, or you can also continue reading below.



A: ‘Trapped Souls: Dana’  is a video capture of Jiwon testing the VFX and Sound code

B: Trapped Souls (youtube clip): is a quick demo video of the intended interaction. Where with a tilt, the accelerometer knows to apply a specific movement distortion to the ghost image based on the x, y position data change. It keep track of your “attempts”. Once you reach a certain amount of attempts, the soul escapes back into the world ❤

Github code here



1. Prototyping & Production 

Materials: Smartphone, Acrylic, Velcro, Paper, Accelerometer ADXL345, Arduino, Bluefruit E-Z Link Bluetooth Module, P5.js

Although a smartphone has an accelerometer in it (and would be a great next iteration of the project, allowing for a more intimate sized object?). We thought it would be fun to solder and work with an ADXL 345 as well as the BlueFruit EZ-Link Bluetooth See Jiwon’s great breakdown of our production process  * here *



2. Fabrication

We used Makercase.com to help us generate box designs with finger joints to laser cut. However, after a first cardboard test, we realized we needed to go back and changes the joints of where the two boxes sat ontop of eachother.


Screen Shot 2018-10-19 at 11.00.04 PM



3. Code Inspiration

For the code we were inspired by Daniel Shiffman’s Nature of Code  physics (like particles + wind).





Some bumps we hit during the production process:

  • Particle Amount: needing to lower the particle amount in the VFX, to allow the graphics on the phone to be smoother (quicker processing time)
  • Trapezoidal Top: trying to make a trapezoidal shape for our original design idea
  • Hiding the Tech: how to hide the smartphone enough so that the pepper’s ghost reflection was the focal point
  • User Affirmation: creating an affirmative response for the user (decided on sound)
  • Sound on Mobile Restrictions: remembering that sound is only button/touch activated on mobile devices, and how to program around that for a solution
  • Title Ideation: we went with a title that implicates the subject matter verses something that highlights the text? (ex: Trapped Souls vs Pepper’s Box)  We do like the idea of thinking about carnival ride names or titles that would implicate/ prompt the needed user action.. see this fun wiki on carnival rides.

Also thinking about synonyms for things like escape:

Screen Shot 2018-10-24 at 10.34.58 AM





4. User Testing Feedback 

(Students + Danny’s office hours) 

box vs bottle:  When having students test out our project, we realized people felt shy about moving our “bottle around”. Danny mentioned he thought it was due to the trapezoidal top, and that due to it looking “intricate or cumbersome?” people felt less comfortable with the idea of moving it around. That maybe just a box would solve that issue.

We think that he was right, in that as soon as we removed the glue, and took off the trapezoidal top, people started feeling a lot freer to shake it around, and flip it 180 degrees. It also got rid of the double reflection we didn’t anticipate, due to the 2 slanted acrylic angles existing in the structure. (1 on the trapezoid bottle top, the other where we hoped for it, within the bottle)


hiding the tech to heighten the illusion:  We also noticed that our side walls were not high enough. That people were confused about which image to look at. So we increased the height of the walls with black paper to help, as well as added a sheet to the top.



5. Potential Future Iterations

Utilizing full capacity of Pepper’s Ghost effect

Taking Danny’s advice into the next iteration, thinking about how to utilize the full pepper’s ghost ability. Right now we are using it to create a “ghostly” transparent image, where the real world acts as the backdrop it floats around on. However, that’s only utilizing really 50% of its ability. (history of Pepper’s Ghost)

What happens if we create more of a set for it? It’s interesting in that due to the angle of the acrylic pane, the floating face looks like its inside whatever image is behind it (example a black piece of paper – it almost looked like the floating face was layered *behind* the paper. Will take some pictures to help illustrate soon.

Also we realize Pepper’s Ghost is really meant to be seen from one angle? if we tried the Pepper’s Cone technique, maybe we could have it seen from all angles – but may experience increased difficulty in hiding the tech:

Screen Shot 2018-10-12 at 1.55.53 AM


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