What a care camera really sees at night: 540 minutes in darkness
We tested a phone in a completely dark room for 540 minutes. It detected zero people—an important limit before relying on any alert.
At night, a fall may go unnoticed for longer. Camera-based systems also face their hardest physical constraint then: without enough light, an ordinary phone camera cannot produce a useful image.
Velia uses a phone camera to provide best-effort signals of possible falls. So we measured what actually happens when the lights go out.
The experiment
A Samsung Galaxy S20+ mounted in a room, plugged in, running the pose detection model at 2 frames per second. Nobody in the room, no lights on. One full night.
The numbers
- 540 minutes of continuous watching, from 21:00 to 06:00
- Peak brightness recorded: 0 on a 0-255 scale
- Minutes with a person detected: 0
- Phone temperature: 20-23 °C. Battery: 100% throughout
Nine hours of flawless operation seeing absolutely nothing.
The system ran perfectly. Camera on, model processing, battery healthy, phone cool. And it would not have seen a person on the floor one metre away.
Why it happens
A phone sensor needs light. No light means no image, and no image means nothing to analyse — no matter how good the AI model running on top. This is not a software problem.
Security cameras solve it with infrared: an invisible emitter lights the scene and a sensor without an IR filter captures it. An ordinary phone has neither.
What this means if you're choosing
It's the question to ask any product that watches a room: what does it do at three in the morning, with the lights off?
- If the answer is a brochure saying "night vision", ask for the number. Real night vision means an infrared emitter, and that shows up in the hardware.
- If it's an app for the phone you already own — like ours — the honest answer is that it needs some light.
What we do meanwhile
Two things, and neither is pretending we can see.
We say so. When light drops below a threshold, the app stops showing "all fine" and says it's watching blind. On all three screens and in the morning summary. Silence must never be mistaken for calm.
We recommend a dim light. A plug-in night light in the hallway is enough for the model to see again. It costs less than any device and it makes the path to the bathroom visible at night.
Why we publish this
Because it's the data we would have wanted before choosing, and nobody publishes it.
A product that only tells you what it does well leaves you to discover the rest after you've bought it — or worse, on the night it mattered.
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