Physically acurate exterior lighting with vraylight dome and HDRI

[sashakataana]

Hello, I have ran into a problem when trying to determine the in multiplier value in order to recreate real world exterior light conditions with vraylight dome and HDRI. I know that the Illuminance value for a typical suset is 400 lux, is there a way to obtain the equivalent in nits (lm/m^2/sr)?

[Corey Beaulieu]

I'll leave the math to someone else, but I would like to say this:

 

An intensity value for light become extremely irrelevant when you try to capture it with a camera, 3D or otherwise. A camera is a device that allows you to control the perception of light in order to capture it onto film and when employed, alters the real world value of light to suit the desires of the photographer.

 

If you use an HDRI of a night sky, Dome at 1.0 and Map at 1.0 is as close as you will ever need assuming you are using a true HDRI. I would worry about your camera settings much more than I would concern yourself about Lux values.

 

To help ensure your light is within normal range (the 1.0/1.0 scenario) look up typical EV for the time of day you want and begin there in your camera and adjust as necessary.

[Tommy L]

There's no standardized exposure value for capturing an HDRI so you have to eyeball the exposure. If you always use the same library then you'll most likely hone in on the correct exposure for that library, but different capture methods yeild different results, different time of day requires different exposure, so a little experimentation is needed.