In infrared imaging it is important to understand that different types of materials affect the temperature value that the thermal camera puts out. For example, if objects of the same material, same temperature give very different temperature results, depending on if the other is glossy and the other is dirty or rusty.
Respectively different material’s emission factor affect thermal cameras results. Wrong emission factor can change the result even by ten or hunderds of degrees (ºC). Good example about different materials effect on result gotten from thermal camera can be seen from this image:
On the left is a normal digital photo of a bucket which has warm water inside. On the right is a thermal image of the same bucket. In the thermal image Area 1 is the surface of the bucket. Area 2 is painter’s tape. Area 3 is Copper tape. Area 4 is Aluminium tape. All four areas emission factors are different and that’s why the temperature results are totally different since the emission factor hasn’t been taken into consideration. On the right upper corner, you can see each area’s temperature value. Buckets real surface temperature is approximately 45ºC.