Whenever the reflectance curve for two physical samples cross over or intersect at at least 3 different points, the two samples are then considered to be a "metameric pair". Metamerism is an important paradigm considered by product assemblers with one big example being automakers who assemble a car using different materials for different parts while seeking a common shade for those parts since the car is expected to match under virtually all types of illumination.
Whenever the reflectance curve for two physical samples cross over or intersect at at least 3 different points, the two samples are then considered to be a "metameric pair". Metamerism is an important paradigm considered by product assemblers with one big example being automakers who assemble a car using different materials for different parts while seeking a common shade for those parts since the car is expected to match under virtually all types of illumination.