In 2015, I found myself with some free time to work on a personal project. I decided to use that opportunity to experiment with sound visualziation while learning more about Raspberry Pis and motion tracking.
I used the Raspberries to capture the foot traffic in three locations of the Uncorked Studios office where I was working at the time. For each location I hang a Raspberry Pi hooked to a PIR motion sensor to record every time a person walked under them. Because PIRs have a wide detection radius (they don't just track what's directly underneath them but also a few feet around) I improvised a filter made of cartboard and masking tape to only track movement direclty below them.
After getting a full day's worth of data, I visualized it against a map of the office. I also used the data to create music by playing a random note within the Dorian scale for each time a person walked by. I used the amazing Tonejs library to play sounds in the browser.