Carpet tile laying, thermogram footage. Thermography records the temperature of surfaces by detecting long-wavelength infrared radiation. The colours show variations in temperature. The scale runs from white (warmest), through yellow, orange, red and purple to blue (coldest). A colour-coded temperature scale is at right, ranging from 15 degrees Celsius (dark blue) to 32 degrees Celsius (white). This footage shows a barefooted person laying a carpet tile. The tile is insulating and gives off less radiation than the person's body and clothes. The person's feet and hands leave visible heat traces on the carpet.