Stop security camera false motion alarms
Most security camera false motion alarms come from a handful of causes: light changes, the night-vision switch, headlights, shadows, rain, insects and moving trees. Find which one it is, then lower the sensitivity, shrink the detection area or switch to people and vehicle detection.
Why plain motion detection is fooled
Ordinary motion detection doesn’t know what a person is. It compares one frame with the next and alarms when enough pixels change. Anything that changes the picture counts: a cloud, a car’s lights, a moth.
So the first job is to find out what is really setting it off. Open a few of the false alerts and look at the clip. The cause is usually obvious once you see three or four in a row.
The usual causes of false alarms
- Light changes: sun through a window, clouds passing, lights switched on or off.
- The IR switch at dusk and dawn: when the camera flips between color and black-and-white night vision, the whole picture changes at once.
- Headlights sweeping across a wall or a window at night.
- Shadows of people, cars or branches moving across the ground.
- Rain and snow, which look like movement everywhere, especially lit up by infrared at night.
- Insects and spider webs near the IR lights. A single strand of web waving in front of the lens can fire all night.
- Moving trees, bushes and flags in the wind.
- Pets, indoors or out.
How to fix security camera false motion alarms
- Lower the sensitivity one step at a time, and test for a day before going further. Too low and you miss real events.
- Limit the detection area. Draw it over the door, the gate or the counter, not the whole picture. Leave out the road, the trees and windows.
- Mask parts of the picture that always move: a TV, a fan, a flag.
- Use people and vehicle detection or line crossing instead of plain motion, if your camera or recorder supports it.
- Adjust the schedule, so motion alerts run only when the place is meant to be empty.
- Clean the lens and remove webs. Spiders follow the insects that fly to the IR lights, so check every few weeks in summer.
At night: infrared, bugs and rain
Night is when most false alarms happen. The infrared lights around the lens attract insects and light up raindrops, and both look huge to the camera.
If a camera only misbehaves at night, try turning off its built-in IR and lighting the area with a separate light instead, or point the camera so it doesn’t face a wall at close range, which bounces the IR back into the lens.
What person detection fixes, and what it doesn’t
Smart detection such as Hikvision AcuSense or Dahua WizSense tells people and vehicles apart, which cuts many false alarms. It works only on supported models and only for those classes.
It still alarms for every person. In a café or a shop, people walk past the camera all day, and an alert for each of them is just as useless as an alert for a shadow. What you really want to know is narrower: someone at the back door after closing, the till open with nobody there.
Alerts only when your sentence is true
Puw is a Windows 10/11 app that works with the cameras and recorder you already have (over RTSP or ONVIF; Hikvision, Dahua and most other IP brands). Its AI runs on your PC and writes a caption for every event. You get an alert only when the rule you wrote is true, not when a pixel changes.
Alerts arrive on your phone as a Telegram message with a photo.
- Write the rule in a sentence: “Tell me if someone is at the back door after 10pm.”
- Draw an area with a question: around the till, “tell me if the drawer is open and nobody is there”. The AI looks at that area only.
- Draw a motion alarm area where you want speed: it alerts within a second, no AI involved.
- Mark ignored areas, like a TV, a curtain or a tree, and they never trigger.
- Puw doesn’t promise a number of fewer false alarms. It needs a PC that stays on, and busy cameras want an NVIDIA graphics card.
30 days free · full version · no card
Frequently asked questions
Why does my security camera detect motion when nothing is there?
Something in the picture changed: light, a shadow, the night-vision switch, rain, or an insect near the lens. Watch a few of the false clips and you will usually see which one.
How do I stop spider webs on my security camera?
Clean the camera and the area around it regularly, especially in summer. Spiders are drawn to the insects that fly to the IR lights. Some owners also use a separate light so the camera’s own IR can stay off.
Should I turn motion sensitivity down?
A little, step by step. Very low sensitivity hides real events too. Shrinking the detection area and using people or vehicle detection usually helps more than turning sensitivity right down.
Why do I get false alarms at dusk and dawn?
That’s when the camera switches between day and night mode. The picture changes all at once, and plain motion detection takes it for movement. A schedule or smart detection helps.
Can AI stop all false alarms?
No. It cuts the alarms that come from light and weather, because it looks at what is in the picture, not just at changes. It can still be wrong now and then, so look at the photo before you act.
Hikvision, Dahua, Lorex, Reolink and other brands are trademarks of their owners. Puw is not affiliated with them.