How thermal cameras work
Every object above absolute zero radiates infrared energy. A thermal camera's lens focuses long-wave IR onto a grid of tiny heat-sensitive elements — a microbolometer array. Each element warms slightly, its electrical resistance changes, and that change becomes one pixel. Raise the scene temperature and watch the radiation, the detector, and the output image respond.
Temperature scales & color maps
A thermal image is just numbers — a temperature for every pixel. The palette maps those numbers to colors, and the level/span controls decide which range of temperatures gets the full color range. Re-paint the same scene and watch how the choice of map and range reveals or hides detail.
Emissivity explained
Emissivity (ε) is how efficiently a surface radiates its heat — from 0 (perfect mirror) to 1 (perfect emitter). A thermal camera assumes a value (here, 0.95). Every object below is the same real temperature, yet shiny low-ε surfaces look cold, because they radiate little and reflect their surroundings instead. Drag the slider on the highlighted object.
Spatial resolution & NETD
Two things decide whether you'll see a small warm target: how many pixels you have (spatial resolution) and how much thermal noise blurs faint differences (NETD — noise-equivalent temperature difference, in millikelvin). Degrade the right-hand feed until the target dissolves into the grain.
The IR spectrum & Planck's law
Planck's law sets how much each wavelength an object radiates at a given temperature. As temperature rises, the whole curve grows and its peak shifts to shorter wavelengths (Wien's law). Slide through temperatures to see why room-temperature scenes peak in the long-wave IR band — exactly where thermal cameras look — while the Sun peaks in visible light.
Facial thermal signatures
The autonomic nervous system redirects blood flow under the skin, and a thermal camera reads the result on the face. Different states leave different fingerprints across the nose tip, the area around the eyes (periorbital), the forehead and the cheeks. Toggle a state and watch the regions re-color.
Happy vs. stressed
Stress triggers sympathetic vasoconstriction at the nose tip — blood pulls away and the tip cools — while the region around the eyes tends to warm. Drag the slider from relaxed to stressed and compare the live face against the relaxed reference on the left.
Fear & anxiety response
A sudden fright sets off the fight-or-flight response: blood is redistributed toward the body's core and large muscles, and the nose tip cools sharply within seconds. Scrub the timeline through a startle event and use the blood-flow control to scale how strong the reaction is.
Anger & frustration mapping
Anger is, thermally, almost the mirror image of fear. Where fear cools the face, anger tends to warm the forehead and the region around the eyes — the "hot-headed" pattern. Switch between the two and read the diverging comparison below.
Emotional contagion
When people interact, their arousal can synchronize — and some studies report that this shows up in correlated facial-temperature changes. Drive Person A's arousal and adjust the coupling between them; Person B's thermal pattern follows, scaled by how tightly the two are linked.
Chronic stress detection
A single startle passes quickly. Stress sustained over weeks shifts the face's resting thermal baseline — the nose tip settles cooler, the periorbital region runs warmer, and day-to-day variability drops. Drag through weeks of sustained load to watch the baseline drift.
Burnout & fatigue signatures
Sustained workload without recovery flattens the face's thermal landscape — warm and cool regions converge toward a dull, low-contrast pattern, and periorbital warmth fades. Balance workload against recovery and watch the contrast collapse or return.
Meditation & the relaxation response
Slow, paced breathing shifts the body toward parasympathetic dominance — the opposite of the stress response. Peripheral vessels dilate, so the nose tip and fingers warm while the face settles. Follow the breathing pacer and let relaxation deepen.
Sleep quality indicators
In the evening wind-down, blood flow shifts to the skin of the hands and feet. Those distal areas warm relative to the core — the distal–proximal gradient (DPG). A rising DPG is one of the most reliable physiological cues that sleep onset is near. Wind down and watch the gradient grow.
Depression & emotional blunting
One feature studied in low mood is blunted reactivity — emotional events produce a smaller physiological response than usual. Present a stimulus and lower the reactivity to see the thermal swing flatten out. This is an illustrative research direction, not a diagnostic.
Mental load & prefrontal heating
Hard mental work raises blood flow to the prefrontal cortex behind the forehead, and the extra metabolic heat shows on the skin above the brow and around the eyes. At the same time, sympathetic arousal can cool the nose tip. Crank the task difficulty and watch the forehead warm.
Focus vs. mind-wandering
Sustained attention holds prefrontal engagement steady; when the mind wanders, engagement sags and drifts before snapping back. Toggle the state and scrub the timeline to watch the attention trace — and the forehead warmth — hold firm or wobble.
Decision fatigue patterns
Each deliberate choice draws on the same limited prefrontal resources. Across a long session of decisions, engagement wanes — the forehead's effort signature fades and choices get sluggish. Drag through the number of decisions made and watch engagement decay.
Flow state signatures
Flow appears when challenge and skill are both high and well matched — effortless absorption. Too much challenge for your skill tips into anxiety (nose cooling); too little tips into boredom. Balance the two sliders to find the flow channel.
Cognitive recovery after rest
After intense work the prefrontal effort signature lingers. Rest lets that heat dissipate and the face settle back toward baseline. Press play to run a rest period, and set the rest quality to control how fast and how fully recovery happens.