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Flux

A box for a venue’s counter or doorway that counts the people in the room and sends Flock the numbers.

It’s a prototype. The case on this page is a 3D design and hasn’t been printed yet.

A render of Flux: a navy box with a 7 inch screen, a cream sensor pill and the Flux wordmark, leaning back on a cream stand.
On its stand, rendered from the CAD.

What’s inside it

Thermal camera
A FLIR Lepton 3.5. It sees heat, 160 by 120 points of it. Owl, further down, is the model that counts the people in those frames.
Door counter
A VL53L8CX, which measures distance in an 8 by 8 grid. It looks down at a doorway from under the case to count people walking in and out. It’s wired up and reading, but it hasn’t been tested on people walking through a real doorway yet.
Microphone
A microphone gives a rough noise level for the room, louder or quieter, not decibels. The case is designed around a separate decibel meter, which hasn’t been fitted yet.
Screen
A 7 inch touchscreen on the front shows the live readings.
Raspberry Pi 5
The computer inside, with an Active Cooler on top.

Owl does the counting

Owl is a small neural network we trained to count people from heat. It runs on the Raspberry Pi inside Flux, so each frame is counted on the box that took it.

It reads one thermal frame at a time and marks each person as a peak of warmth. Only the count moves on. The frame never leaves the box.

We trained it on generated thermal frames and six public thermal datasets, never on anything a Flux unit recorded, then tested it on footage it had never seen. It hasn’t run in a venue yet. The results are on the research page.

Owl's path through a frame: a 160 by 120 thermal frame goes in, through the network's layers (718,550 weights), and out comes a 40 by 30 map where each person is a peak. Here it finds 3 people.
One frame through Owl. This frame is generated, not a picture of real people.

What leaves the box

Every 30 seconds Flux is built to send a few numbers over Wi-Fi or Ethernet: the people it counts, door crossings, an estimate of how full the room is, and the noise level. No images, video or identities leave it.

The Flux sensor deletes the frame and sends only “count: 3” to the Flock server.

In parts

Front to back, in the order it goes together.

Every part of the Flux case pulled apart and named, front to back: the cream sensor pill, with the thermal camera and status light behind it, and the Flux wordmark; the printed navy body with the door counter in its chin; the sound meter and 4G antenna to one side; the 7 inch touchscreen; the battery; the 4G board, Active Cooler, Raspberry Pi 5 and power board; and the navy acrylic back sheet with its CHARGE, USB and Ethernet ports.
Rendered from the CAD. Open it full size to read every name.

Put it together

One bar runs from every part apart to the finished box.

Pulled apart: Every part of the case, laid out front to back.

Pulled apart

Every part of the case, laid out front to back.

Drag the bar to build it.

With the back off

The back of the screen, the battery on its end, and the Raspberry Pi with its cooler, cabled to the ports.

A mockup of the planned Flux build with its back sheet off: the back of the 7 inch screen, the battery standing on its end, the Raspberry Pi 5 with its cooler fan, the ports along the top and orange power cables between them.
A mockup of the planned build, made from the CAD.
The same view in the CAD: the Flux body from behind with the back sheet off, showing the screen, battery, Raspberry Pi and cables.
The same view in the CAD.

Where it goes

On a counter

It leans back 12 degrees on its cream stand, screen to the room.

Over a door

A camera arm tilts it 15 degrees down, and the door counter looks 65 degrees down at the floor of the doorway.

Power and ports

A battery inside runs it through a USB-C power board and charges through the CHARGE port. Ethernet and USB are on the back too.

Flux on a black camera arm, tilted down from a wall.
On the arm, over a door.
The back of Flux: a navy sheet with the Ethernet, USB and CHARGE ports along the top, two vent grilles and the Flux wordmark.
The back, with its three ports.

The models behind it

Owl is one of four models in Flock. One page covers all of them.

How the AI worksRead the research