I am trying to make a city environment at night and in daylight. For the moment I am only interested in having realistic lighting conditions, so I don’t want to force certain values of emission, intensities, etc. so that it just “looks good”. I want to be as realistic as I can with the lighting, using the sun real luminosity, lights’ normal wattage/luminosities, etc. Once this is achieved, I can say I understand the graphic settings and I’ll take some art-style liberties regarding the lighting.
I am struggling with emissive materials, the indication of the “intensity” slider in the HDR color picker is not clear. How bright is it? how many lumens per m² does it emit? that’s the kind of answer I want.
The emissive materials simulate some windows with the lights turned on (windows with the lights off don’t emit). I can roughly estimate how much light is going through them in the real world, hopefully once I understand the transformation between the physical flux units to Unity’s unities, I’d be able to set a realistic night lighting.
So far, once I could balance the moon’s light (0.5 Lux) and the city’s lights by adjusting the “intensity” slider of the emissive window materials so that after baking the lights it looked okayish, I tried changing the settings to a daylight (just changed the moon for the sun 120000 Lux), and the windows looked much brighter than non emitting windows.
Normally, in a daylight setting, you wouldn’t be able to distinguish which rooms have the lights on, and which have them off, because of the contrast. The reflection of the sun’s direct and indirect light on the windows is vastly brighter than whatever light can come from inside the windows. Something is clearly wrong here, I definitely don’t understand how emissive materials work.
Thanks for your time!
Emission in HDRP has a toggle for LDR or HDR values, if you’re setting up physically based using these values for colour, then you can measure that IRL and input the values.
If you’re using that later as a more creative step then leave it at default white for now.
Using the emission intensity values will allow you to input the physically based values in NITS and EV and probably LUX too IIRC, I recommend taking this path first as its much easier to grab real world values here for your scene balance.
Taking a Samsung phone @1300nits peak brightness and moving it in out of a darker room and a lighter space should also reflect similar results if you were to walk from your room to the outside day.
You also have exposure weight. This is how much of the EV range you want that value to effect (0-1) this can be used both creatively and to balance specific lighting, like neon that tends to be able be seen during the day as well as night.
You could also use this to balance statically or dynamically creative elements like magic.
This method I generally find easier if drawing from references and physical values, later if there is any creative wiggle room from debugging all the lighting in the scene then you could optionally use the HDR/SDR values.
Both are there mostly for creative freedom, you don’t have to use both but in some projects you may be required to be as accurate as possible.