Final answer:
The artist Campin used atmospheric perspective in this altarpiece to create a sense of recession in space.
Step-by-step explanation:
The artist Campin used atmospheric perspective in this altarpiece. Atmospheric perspective is based on the principle that objects further away appear smaller, grayer, and less distinct. It is used by landscape artists to create a sense of recession in space on a two-dimensional surface. For example, Albert Bierstadt's painting of The Rocky Mountains, Lander's Peak demonstrates the use of atmospheric perspective.