The exposure
How bright one cd/m² is drawn, and matching it to a scene.
Every light is worked out in photometric units: candela from the light, lux
at the eye, cd/m² on the screen. look.exposure is the number one cd/m² is
drawn as, before the tone map.
exposure_ev100 gives it for a camera's exposure value at ISO 100, metered
as a camera's saturation-based speed has it:
import { exposure_ev100 } from "@aeronautic/lights/physics";
<Lights look={{ exposure: exposure_ev100(3) }} />;| EV100 | scene |
|---|---|
| -2 | a moonlit landscape |
| 3 | a floodlit apron, the default |
| 8 | a lit interior |
| 15 | a sunny day |
The scene round the aircraft has to be lit to the same scale for the lights to sit in it: a sky of 6000 cd/m² drawn at 1 is an exposure of 1/6000. The lights' own light on the scene, three's lights, is in the same units: a spot light of so many candela, times the exposure.
By day the position lights are a few candela against a sky of thousands of cd/m². Drawn at the day's exposure they are the specks they are in life.