7 Technologies that Count People (Buildings, Offices & Agnostic)
In the process of building Density, we’ve explored and designed a number of alternate technologies.
Building analytics is an evolving space — There’s old tech and there’s new tech. Since we often field questions about the various methods of counting people, I thought it would be helpful to document 7 technologies that make up the space.
#1 — Density Open Area
About:
Density uses depth data and machine learning to anonymously count people in open space.
Industry:
Industry agnostic. The system is designed to measure how people use any open area in real-time without invading occupant privacy.
Cost:
Hardware fee and annual data fee, variable by volume.
Benefits:
Users are able to access (from Density website):
- 60% reduction in cost to deploy (vs. camera / optical alternatives).
- Up to 20 foot range, 40 foot effective diameter (4x coverage of alternatives).
- 1,325 square feet of coverage
- Historical occupant pathing and heatmaps
- Desk and room availability (+ release)
- Touchdowns and dwell time
Includes real-time API. More info — http://density.io
Pricing:
Limitations:
No identity tracking; Powered device (not battery operated)
Data type:
Depth data and radar.
#2 — Density Entry
About:
Density uses depth data, machine learning, and computer vision to anonymously count people.
Industry:
Corporate offices. Companies in the Fortune 1000. The system is designed to measure how people use a company’s offices, conference rooms, and other work areas.
Average Cost:
Hardware fee and annual data fee, variable by volume.
Benefits:
Anonymous data, designed for corporate offices, real-time API. More info — http://density.io
Pricing:
Limitations:
No identity tracking; Powered device (not battery operated)
Data type:
Depth data and infrared lasers
#3— Cameras or “Optical Vision Sensors”
About
Most cameras see in flat color images. Smart cameras use second-by-second changes in pixel color to determine movement and identify people or other objects in a scene.
Industry
Retail, building security, corporate offices.
Average Cost
Variable based on the device’s intelligence and the analytics system behind it. Companies usually charge a hardware fee and an analytics or dashboard fee. Some examples:
Benefits
Inexpensive, impressive analytics
- Cost: Cameras are relatively inexpensive and they come in a wide variety of form factors.
- Analytics: Cameras on the cutting edge have impressive on-board computer vision. They can generate a ton of information about the areas they’re deployed in. People tracking, facial recognition (i.e. Face++), object detection, etc. As it’s become more practical to make use of machine and deep learning, camera systems have become impressive.
Limitations
“Handoff problem,” privacy, culture, and security
- The Handoff Problem: When pointing multiple cameras into a room, you have to overlap their fields of view. If you don’t, or if you’re using multiple cameras, they have to intelligently make sense of the people that disappear in-between the FOVs. This is called the handoff problem and it takes some processing.
- Lack of privacy is a camera’s biggest limitation. Some smart cameras will “anonymize data locally,” meaning they will blur or obscure a person’s face or downsample the image’s resolution so it looks fuzzy. It’s a good method but can be difficult
- Culture: In an office setting, it can be difficult to get beyond the pilot stage with camera solutions for counting people. Often, employees push back as a system looks to scale.
- Security: For buyers with a robust infosec posture, camera systems are an ideal target for hacking. Even benign systems that obscure a video stream locally can be compromised and made to do otherwise.
Data type: RGB video or flat images.
#4 — Active Infrared or “Break-beam” (AIR)
How it works
Break beam sensors have an infrared emitter and an infrared receiver. The sensors are typically placed on one side of a doorway (or both sides). The tech looks like this:
Standard AIRs count the number of times infrared light is “broken” or passed through and at the end of the day, the user (you) divides the number by 2 to determine the total number of people that came and went. It’s pretty analog.
More intelligent AIRs claim to do bidirectional movement.
Industry
Retail
Average Cost
Benefits
None, really. They’re battery operated but they’re inaccurate. Not good for counting people.
Limitations
Not accurate
- Blindness: Break beam sensors are inaccurate. The sensor becomes blind when two people enter at the same time (side-by-side) or enter and exit at the same time.
- Human movement is complex: Break beam sensors rely on signal processing to sort out when a person has entered. The signal, which looks like the figure below is hard to make sense of when lines form or people bring boxes and bags with them.
Data type:
Signal and signal processing algorithm
Each time Jordan (Density co-founder and head of algorithm) punches, this is what an AIR break beam sees:
Those two lines (blue and green) represent two AIR sensors spaced very close to one another. The spikes in values are increases in power consumption. The closer Jordan’s arms are to the sensors, the higher the values.
To a signal processing algorithm, these spikes look exactly like someone entering / exiting as it does when someone is punching, moving their arms while walking, carrying boxes, and standing in line.
Because it can’t distinguish between these different human behaviors, it makes AIRs an unreliable people counting technology. They are very inaccurate.
For more weird human behavior, see some of the odd stuff we’ve captured in the field.
#5 — WiFi Tracking or “WiFi / MAC Address Tracking”
How it works
The image above is an cartoonish version of how devices track your phone. Years ago, one of our very early prototypes was a MAC Address Tracking unit. Here’s how it works:
- Your phone is always looking for known WiFi networks (home WiFi, work WiFi, etc). It does this out of convenience so you can automatically connect to a known network without manually selecting it.
- The way your phone finds a WiFi network is by sending out what’s called a “probe request.” This probe request is kind of like your phone saying, “Hey my name is, Andrew.” But instead of “Andrew” it sends “40:68:AD:80:D3:A0,” which is a MAC Address unique to your phone and your phone only (it’s globally unique). You can look yours up in the Settings › About section of your smartphone. Fun fact: Bluetooth has one, too.
- Technicalities aside, the thing to know is pretty much all WiFi routers are capable of tracking your phone. In fact, your MAC address is how a WiFi router or access point serves internet to all of your devices: your laptop, smartwatch, Fitbit, phone, Nintendo Switch, etc. They all have MAC addresses, they can all be tracked, and you do not need to be connected to the internet. All you need is to have your WiFi turned on.
- So, you’re in a building and your phone is reaching out saying, “I’m here!” Multiple routers are listening and triangulating. They compare the relative strength of that signal to one another and can approximate where you are in the building. They also know what other devices you usually carry with you (i.e. smartwatch, iPad, etc). Most important, they can tell if they’ve seen you before (even if the last time they saw you was in another country during a business trip).
- The routers roll up this data and send it to an analytics platform that looks like this:
*It is possible to fake or change a MAC address. This is called “spoofing.”
Average cost
Varies widely by platform. Depending on the analytics, it can vary from tens of $$ / month to tens of thousands of $$ / month. Your existing enterprise WiFi system will have this as an upgrade option.
Industry
Retail, Corporate Offices
Benefits
Low cost, widely available, and ambient.
Limitations
Privacy. Inaccurate at a room level.
Invasive: Depending on the environment you’re deploying the technology into, this can be an invasive technology. It is not “opt-in;” meaning, the users the system tracks haven’t given their permission.
Inaccuracy: The real downfall of WiFi tracking, though, is inaccuracy. The system usually isn’t granular enough to determine the use of a specific room. So you end up with heatmaps and approximation like graphic above.
#6 — Seat Sensors
How it works
Seat sensors are battery operated motion detectors + tape. You can see the removable pull tab on the side of the device above.
The sensors run in low power waiting for movement. When they see movement, they transmit “Movement!” back to another device nearby. That device is powered and usually has a 4G internet connection.
If you have 1,000 employees, you stick these beneath 1,000 desks, and however many conference room tables you might have.
Average Cost
Varies by provider. Some bundle it with their service. Others charge separately for the hardware. It’s a pretty low cost solution, though (10s-100s of $$).
Industry
Offices
Benefits
Seat specific data. Battery operated. Low cost.
Limitations
Battery operated scale. Privacy (sorta).
Battery: If this is a long-term solution and you’ve deployed them in the thousands, when a battery operated device dies, you will have to retrieve and redeploy them in the thousands.
Privacy (sorta): Technically, you can use this system to track how long someone is at their desk. The privacy issue is dependent on how you structure your analytics and how you use the data. Know that systems like this have the ability to track an individual’s time-at-desk if you associate an employee’s identity with a device. Used benevolently, they can be helpful in understanding use of certain furniture.
#7 — Thermal
How it works
Thermal uses body heat and computer vision to determine objects. Looks like this:
Industry
Retail, Offices
Average Cost
The most popular thermal people counter is about $1,500 / device. Price varies by vendor. The underlying technology is not terribly expensive (10s-100s of $$ off the shelf).
Benefits
Anonymous
Limitations
Unreliable accuracy.
Thermal systems rely on motion to distinguish humans. It has difficulty when people stand still, when they overlap, and when they carry warm things (like laptops). The image below is two people near one another but sensor only counts one.
Extra — Ultrasonic
How it works
Ultrasonic sensors bounce inaudible sound off people as they walk by. Each one has an emitter and a receiver.
Industry
Robotics
Average Cost
They are low cost. Ballpark $50–$100 (max).
Benefits
Low power
Limitations
Accuracy. Put simply, if someone wears a fuzzy coat, ultrasonic devices get confused because the sound waves bounce inconsistently. If you’re trying to count people, there are better technologies… unless everyone is wearing denim. It does very well with denim.
