Hi,
Some more details on the new exposure settings in 4.19 :
- The exposure value from the viewport EV100 slider is defined as Exposure = 1 / (1.2 * 2^EV100)
- The relationship with the PPV camera setting is EV100 = log2( N^2/t * 100/S ) where N is the aperture, 1/t is the shutter speed and S is the ISO.
- The scene color is defined in cd/m², before the exposure is applied. It can be inspected by using the PixelInspector tool.
- To isolate the effect of exposure on the final color, disable the “tonemapper” post process in the show flags.
- Directional lights are in lux (lm/m²) and sky lights are cd/m² (as emissive materials).
- When using the “manual” metering mode, the scene can go dark because the default values define an EV100 of 9.91 (where as most scene are made for an EV100 of -1.2).
- When using auto exposure with realistic lighting values, increase “Max Brightness” to 10K and “Histogram Log Max” to something like 16. Otherwise, it will go white.
- Prior to 4.19, the point lights units suggested to be in lumens but it was not in practice.
- IES profiles work in the unit type of the lights.