概述

What is Thermal Surveillance?
Thermal surveillance cameras play a critical role in security by enabling night vision, zero-light operation, and penetration through smoke, fog, and adverse weather conditions. Unlike optical imaging, which relies on visible light, thermal imaging detects infrared radiation emitted by objects. Understanding the parameters of thermal imaging is essential for accurate performance evaluation, procurement decisions, and regulatory compliance.

Key Technical Parameters and Their Definitions
NETD (Noise Equivalent Temperature Difference)
Definition: The smallest temperature difference a thermal camera can detect between two adjacent points, measured in millikelvins (mK). Lower NETD values represent higher sensitivity. For example, a camera with NETD 40 mK can distinguish a target at 36.04°C from a background at 36.00°C.

Spatial Resolution
Definition: The ability of the camera to resolve fine details of an object, determined by sensor pixel pitch and optics. Expressed in milliradians (mrad) or Instantaneous Field of View (IFOV). A smaller IFOV means sharper details at longer distances.

Thermal Sensitivity vs. Resolution
Sensitivity (NETD) measures the ability to detect small temperature differences, while resolution measures the ability to distinguish small physical details. Both factors are critical in evaluating camera performance.

Wavelength Range
Definition: Thermal cameras generally operate in LWIR (8–14 μm) or MWIR (3–5 μm). LWIR is best for passive human detection, while MWIR is more suitable for high-temperature industrial applications.

Thermal Camera Events
The thermal cameras can be configured to detect specific kind of exceptional situations, such as fire, smoke, overheating and others. When the situation occurs, the thermal camera will send an alert to the NVR along with the thermal values.

Bi-Spectrum Surveillance
Some of the thermal cameras come with two lenses - one is used for thermal imaging and another is for the standard visual imaging with full color range. The benefit of the bi-spectrum cameras is the accuracy of the events (thermal) combined with the accurate color proof (visual).

應用

The thermal surveillance applications include:

Fire Detection Alert- Instantly detects and alerts when temperatures exceed fire threshold levels.

Overheating Detection - Monitors and alerts on critical equipment overheating.

Smoke Detection - Detects smoke for early fire warnings based on thermal and visual cues.

Enhanced Intrusion Detection - Detects intruders in darkness, undetectable by standard visual cameras.

Human Body Temperature Detection - The special models are tuned to detect the small variances of the human body temperature.

Smoking Detection - Identifies smoking behavior in restricted areas.

解決方案

ACTi offers a wide range of thermal cameras with different form factors, including bullets, turrets and PTZ. Read More

Since the thermal video stream is digitalized inside the camera and delivered by using the standard streaming protocols, therefore from the NVR perspective these cameras are considered normal surveillance cameras. Some of the cameras deliver two streams to the NVR - both visual video and the thermal video.

At the same time the NVR can receive the events from the thermal cameras, based on the type of detection, such as fire alarm, smoke alarm, high body temperature alarm, etc.