Every object emits heat rays that become visible light at high temperatures, e.g. glowing iron. In case the temperatures of the heat emission are only a little above the ambient temperature then the wavelengths of the heat rays are within the invisible infrared range (IR range). Using an IR camera infrared rays can be recorded and depicted showing different colours (camera display, PC, hard copy). On the basis of the defined colour/temperature scale, the temperatures can be determined by means of the colour nuances. The coloured depiction makes important differences particularly apparent. The correct preparation and interpretation of heat images require a sound expert knowledge as heat rays are subject to many influencing factors as climatic conditions (ambient temperature, incidence of sun/shadow), construction materials, etc. Thermography belongs to the non-destructive and low-cost test methods and is applied for the localisation of line systems and leakages, determination of heat insulating measures as well as a subsequent check of the successful implementation of the action, etc.
