Requirements for illuminance
Good visual communication and recognition requires a sufficient level of brightness on objects and, above all, on people's faces. Therefore, the surfaces and "spaces" in which people move or work have to be sufficiently illuminated. This can be fulfilled by ensuring sufficient levels of average cylindrical illuminance.
Modelling is the balance between diffuse and directional lighting, and is a property of light whereby an illuminated object is made to appear natural, neither too smoothed nor too hard or sharply illuminated. The general appearance of an interior is reinforced when its structural features, as well as people and objects in the room, are illuminated so that shapes and textures appear clear and pleasant.