How Does a Thermal-sensing Camera Detects Motion

Depending on the unit's settings, it is usually a combination of two triggers:

• The PIR sensor detects body heat and has a wider detection range which means it can still detect even outside the camera's field of view.
• The camera’s motion detection identifies visible movement (some units require the movement from a person or vehicle-shaped object).

In the sample image below, the camera with a check mark will start recording because the person was captured moving and has body heat. On the other hand, the camera on the left may not record because while it can detect the heat signature, the movement is towards the camera which has a minimal chance to trigger motion detection, compare to the other camera where it clearly sees the movement because the movement was across the camera's view.

It detects best if people move ACROSS the area (see green check mark) THAN TOWARDS (see red X mark) the Thermal camera. 

If your camera continues to record when it is not supposed to, check out Understanding and Addressing False Triggers to learn what could possibly cause the issue.