Good Lighting Design

A good environment lighting design is one that does not create pain in the human eye. 

Think of a restaurant lighting design. A light bulb that has high lumen can be a pain to look at when its light source is parallel to the human vision in the room.

If we could draw a lightcone of an overhead light in the room, the best position its user can be is the underneath of the light source within the lightcone. In this way, the user is refrained from looking upwards directly into the light source.

A reflected light can solve the issue of a high lumen light shooting into the user's eye in the direction of his sight. The same goes for incandescent light, low voltage filament light, and diffused light. If a spotlight is needed to be used, the lightcone method can be applied. 

Objectively, a high lumen light source prevents one from looking at the direction of its emission. Imagine looking at the sun with your naked eyes. If the light source is at the ceiling, the ceiling space doesn't want anyone to look at it. If it is on the garden floor, it doesn't want the user to look at the floor.

A light source can control the spatial perception of an environment.