4.19 Physical Lights

[Maximum-Dev]

One thing that did not make the documentation with this most recent update for 4.21 is a section detailing the workflow for using the PLUs and Auto-Exposure. It's something that I want to add along with some reference values to use for different lighting situations (ie, sunny day, overcast, night, etc) that are in line with what you can find on other sites with tables of exposure values (for example, Wikipedia).

Just know that it's still on our minds to add these things and reduce the confusion (as much as possible). Unfortunately, I don't have an ETA, but I'll push to get something added before the end of the year (which isn't really that far off!).

Hello,

Any news on those workflows / example content?

[Baguetteness]

Hello, anyone has any insight on what is the best way to approach particle emissive values using physical light units? A day - night difference of over 14EV makes the values too extreme to keep a fixed value in some cases (magic vfx and such). Something like fire would be fine keep constant easily but anything else is very arbitrary. Should I ditch using PLU?

[Daedalus51]

Hello, anyone has any insight on what is the best way to approach particle emissive values using physical light units? A day - night difference of over 14EV makes the values too extreme to keep a fixed value in some cases (magic vfx and such). Something like fire would be fine keep constant easily but anything else is very arbitrary. Should I ditch using PLU?

I think you wanna use exposure override in shaders for effects like this Thats common practice these days for stuff like this

[rosegoldslugs]

I think you wanna use exposure override in shaders for effects like this Thats common practice these days for stuff like this

Yeah, this is super helpful for gameplay oriented stuff especially. Just divide your final emissive output in the material by the EyeAdaptation node and whatever luminance you have before that node will remain constant regardless of exposure.

[Baguetteness]

Thanks a lot guys

[Alessiana]

Hi,
Do you know why if I put a movable object in a fully closed room (6 walls with no doors or windows), that object keep being lit by the stationary skylight? I tried everything (as far as I know) like increasing volumetric lightmap samples, put lightmass importance volume, lightmass character indirect detail volume, volumetric lightmap density volume, turn on ambient occlusion, increase the building quality.

I am a bit lost right know,
Thanks in advance

[redfox22x]

So, I finally had time to update to 4.21 over the weekend and try out a few things!

2. skin doesnt show spec anymore
3. the hair of her is set to black, for some reason it renders light brown when using physical values

Any work around for the spec on subsurface materials besides disabling pre exposure??
Left - Pre exposure enabled / Right - Pre exposure disabled

I noticed that if i switch view modes and then go to lit again it displays proper spec for a while....

[Nerdsbeware]

Any work around for the spec on subsurface materials besides disabling pre exposure??
Left - Pre exposure enabled / Right - Pre exposure disabled

I noticed that if i switch view modes and then go to lit again it displays proper spec for a while....

do you have r.sss.checkerboard enabled? You have to use that if preexposure is enabled.

[redfox22x]

do you have r.sss.checkerboard enabled? You have to use that if preexposure is enabled.

That did it thank you!

[Daedalus51]

Maybe that should be set as default automatically when enabling pre-exposure?

I really hate that you have to put 20 different settings all over the board to get this working! PLS just make one switch and that's it

Otherwise, this will always be super error prone^^

[Afflictor]

I've noticed when I use a directional light at 100,000 lux and use F9.0 with a shutter speed of 125 & iso 100, any attempts to use an exponential height fog in the scene results in black fog... is this a bug? Has anyone used exponential height fog successfully with these more accurate light settings? I'm on ue4 4.21.

[rosegoldslugs]

You need to use brighter color values. Based on the luminance of the sky and directional light during most lighting conditions, the default luminance of fog being ~1 means it isn't going to be visible. You can eye ball the value or sample from the scene color of the sky to get fog that blends into it better and is visible at that range.

[Afflictor]

Thanks! Rosegoldslugs, that did the trick. I changed the value in the HSV color picker to something around 10,000 instead of the default of 1.

[Alessiana]

Hi,
I made a simple scene with cubes and it seems impossible to have dynamic and static object in the same level with the same lighting



Do you know any tips?
The light is pretty standard. With physical light or without the result is the same.

[TCBmbw]

Hi guys,

I'm just looking for some advice here. I'm following the thread (and tutorials) for a couple of month and I'm also pretty disappointed and confused with this sloppy implementation.
As a 3D Artist, not lighting artist, I want to use physical lights without a rocket science degree or 1000 workarounds.

To sum it up - at the moment physical lights are not working properly and I have to eyeball stuff anyway, right?
So would you suggest to use the "old" exposure workflow and wait till this feature is implemented properly - why should I invest time in something, which does not work the way it should?
This is no rant, I just ask for some advice regarding this confusing topic. At least, for me it masks no sense to guess (actually breaking) lighting values in an actual physical lighting setup (?).

Thx