Skip to Content

A Sensor for Logging People Traffic at the Gym or Café

Startup Density says its Internet-connected sensors can make it simple to count people all over your city.
July 28, 2015

Coupa Café—an extremely popular coffee shop in downtown Palo Alto, California, that’s typically jammed with Silicon Valley tech types—was experiencing a lull in traffic on a recent Friday morning.

I knew that not from visiting or calling, but by opening up a new app called Density on my iPhone that keeps track, in real time, of how busy businesses are. The app is made by a San Francisco startup of the same name, and it works by surfacing data collected by small, Internet-connected, infrared sensors  in the doorway of each business.

Density, which launched in July, is trying to solve a deceptively tricky problem: while there are tons of sensors in our phones and an increasing number of them in our homes that can tell us all kinds of things, it’s still hard to get a good idea of how busy a specific place is unless you’re there or get in touch with someone who is. Getting a better handle on this, says Density cofounder and CEO Andrew Farah, can make it simpler to figure out things ranging from when is a good (or bad) time to visit the gym to which conference rooms are free in your office.

So far, Density has installed prototypes of its sensors in over a dozen businesses, including several coffee shops in the Bay Area and in Portland, Oregon. Farah says the company will start installing sleeker sensors—small, square-shaped white boxes with a black plastic face, which connect to another gadget that houses the Wi-Fi radio—sometime in August. Density envisions the data collected by these sensors providing insights to businesses of all sorts, and potentially being added to apps that consumers can use, like the one I tried (though Farah says it’s meant to be more of a demo than a regular app, Density does plan to add more locations to it). The company charges $25 per month for the hardware and access to its service; it’s targeting businesses that sell things like cash register systems to retailers, which will roll them out to the retailers.

There are existing ways to count pedestrian traffic, such as by using surveillance cameras or so-called break-beam systems that keep a tally based on how often their infrared beam is broken by a passerby. But Farah says Density’s aim was to come up with another method that did away with privacy concerns people might have when it comes to cameras, while also collecting data in real-time.

Chris Harrison, an assistant professor of human-computer interaction at Carnegie Mellon University who recently worked on a project that used smartphone cameras as multifaceted monitors that can answer questions about the world around you, sees Density as more practical in the foreseeable future than a lot of other Internet of things gadgets, saying it’s dealing with a “very well-constrained problem.”

He is concerned about how accurate Density’s method of people counting using infrared sensors can be, though. Farah wouldn’t say how accurate the company’s sensors are at picking up humans entering and exiting a business, but says it’s “accurate enough to rely on,” especially when it comes to sensors placed by a standard-width, single door.

Keep Reading

Most Popular

conceptual illustration showing various women's faces being scanned
conceptual illustration showing various women's faces being scanned

A horrifying new AI app swaps women into porn videos with a click

Deepfake researchers have long feared the day this would arrive.

2021 tech fails concept
2021 tech fails concept

The worst technology of 2021

Face filters, billionaires in space, and home-buying algorithms that overpay all made our annual list of technology gone wrong.

glacier near Brown Station
glacier near Brown Station

The radical intervention that might save the “doomsday” glacier

Researchers are exploring whether building massive berms or unfurling underwater curtains could hold back the warm waters degrading ice sheets.

Professor Gang Chen of MIT
Professor Gang Chen of MIT

In a further blow to the China Initiative, prosecutors move to dismiss a high-profile case

MIT professor Gang Chen was one of the most prominent scientists charged under the China Initiative, a Justice Department effort meant to counter economic espionage and national security threats.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.