Why night snow triggers everything and lower sensitivity is the wrong fix

[spb-andrey]

Every winter the same thread appears. The camera was fine all summer, the first snowfall arrives, and by morning there are four hundred clips of nothing.
The reason is the infrared LEDs sitting a couple of centimetres from the lens. Anything close to the glass is lit far harder than anything at distance, so a snowflake twenty centimetres away comes back as a bright white sphere the size of a fist, crossing the frame in a fraction of a second. Rain on a dome does the same, a moth does it better, a spiderweb strand does it all night at a steady rhythm.

Which is why the sensitivity slider cannot fix it. That flake covers more pixels, with more contrast, than a person at fifteen metres. The setting that finally silences the snow is well past the setting that silences the person walking up your drive, so no value on that slider is the right value.

Zones help only partly. On plain motion detection there are no objects, so zones are evaluated per pixel: they shrink the area in which snow can trigger you and do nothing about the snow falling inside the zone you care about.

What removes weather is changing what raises the event, from "pixels changed here" to "there is a person in this frame". A snowflake is not a person, a car or a dog.

The catch is that confidence drops in infrared. Someone reading 0.85 in daylight can sit at 0.55 as grey on grey. The default threshold is 0.5 and the common tweak is 0.7 to cut daytime noise, which quietly costs you detections after dark. Tune that number on night footage.

What is your threshold set to, and did you pick it in summer?

The weather section: https://getguardianeye.com/blog/camera-detection-zones-guide