Well, there’s also an atmospheric fog and a skylight, both with default parameters. DL and SL are stationary, lighting is baked. No background. With dynamic sun it looks something different, by the way.
Oh, wait. It looks normal during gameplay. Wha?..
Yeah that makes sense. I don’t think we ran into that issue since our cutscenes are a little different, but I guess the only way around that currently is using the EV chart on Wikipedia and matching the manual settings. Interesting idea about the ‘tonemapper node’ though.
If something appears different in gameplay vs. editor (or by toggling ‘G’ in the viewport), then you most likely have something disabled in the viewport properties compared to what is enabled in the Post-Process Volume. Just hit the “Reset Viewport” option to verify easier. It’s going to look weird though, because the Atmospheric Sky doesn’t reach the average sky luminance by default, so it’ll be a bit darker.
They should be identical. Just to be sure, you have the new checkbox in the Project Settings enabled that switches the auto-exposure in the PPV to use EV100 and not the f-stop? It’ll change the text beside the input
Setting up lights is a little tedious, purely because there’s sooooo many variations with drastically different intensities. I’ve seen readings of incandescent bulbs from 8 lumens up to 4000 lumens. It’s better to just get them in a ballpark and adjust based on artistic liberties, unless you can find specific values for something you’re recreating.
Nah, default and game view are same, only playtest looks normal. But that’s because instead of deleting reflection probe I just hid it. After deletion in-game scene also looks alien. And I don’t have a post-process volume, forgot to say.
I honestly believe the best we can do here is nail the exterior and then derive what looks good from it for local lights. These values seemed a bit weird for me so far as well (looking again at my example of that 1000 lumens light bulb in my living room and comparing what I photographed from it with in engine results) and I especially struggle with those angle things in regards to lumen.
If you want to make it really correct, a light (spot) using lumens would need to react according to it set cone angle. Meaning: while having the same amout of energy distributed, the perceived brightness varies greatly depending on covered surface (read: angle of distribution).
So there is that as well^^
Cheers^^
So… I’ve done a little experimentation with my scene and found something interesting. Maybe a bug.
Same setup: stationary directional and sky lights, atmospheric fog, and one sphere reflection probe. Everything at default settings, with the exception of DL: its intensity is set to 70000 lux.
On the first screen is how scene’s lighting normally looks with reflection probe (the intended look). On the second one reflection probe is hidden (or deleted, doesn’t really matter) - materials go wild, sky is normal, and it looks like that the guy at the right side is the only survivor. Note that if we’ll check reflections visualization, there won’t be any wild overbright. But if we’ll turn specular off, like on the third screen, - everything’s back to normal (well, mostly).
I feel like some sort of better documentation or explanation on what has been changed is really needed. Ideally it would be a good idea to have Epic do a livestream with the people responsible for the implementation explanaing the new system and addressing common complaints from this thread and previous workflows.
If not, someone from the community that can get all the nuances. I’m familiar with photography terms but not a pro lighter and reading this discussion on the current state of things did nothing to clarify what’s going at the moment and would make me rely on eyeballing values as always anyway.
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!).
For me this whole physical light thing is still not working out at all… I tried to setup a night scene based on this rule here… Looney 11 rule - Wikipedia
After importing and tweaking my custom HDRI Skybox and camera values, Shutter Speed 200, ISO 200, F-Stop 7 to 11 i throw in a Pointlight in my scene with a value of 900 lumen or 1300 lumen and i see nothing… the light is still pitch black. Values above 100.000 start to give me some light which is kinda crazy.
For a night scene that’s not correct - The Looney Rule is meant for taking pictures of the moon/moon’s surface, not a whole night scene. You can get a better idea of a night scene exposure here: Exposure value - Wikipedia
I’m still personally struggling with the candela/lumen units. I still feel like I have to multiply all the units by 10-100 to “feel” right and that’s frustrating not knowing for sure. Daedalus51 mentioned this very early on in this thread, but I haven’t really seen a response for it, unless I’m missing something.
Some documentation/example scene I think would do wonders for a lot of questions here in this thread.
Yeah i also saw the video from Daedalus51 but i was thinking that this “issue” is kinda fixed since we are what 2 UE versions ahead from the version he is using in his video ?
Lumen and Candela values are so off for me no matter if i try a day interior scene with interior lights or a night scene.
Ouh i thought the looney Rule was kinda the oposite of the sunny 16 rule, thanks for clarifying this. I can’t find any night values on the wiki page you have shared… What would be the right values for a night scene/night interior scene ? I guess Shutter and ISO at 100 and a low F-Stop value ? i also had some problems to find the lux values for the moonlight intensity. Wiki says for full sun light 100K to 125K Lux, for moonlight it says 0.1 to 1 Lux, which seems kinda low for me.
That’s correct. The range between the sun light and pretty much anything else, practical or natural, is extremely high. Even the range of the sun itself between noon and sunset is pretty extreme. The Lux values also include the sky contribution, so your light value will be slightly lower.
For night time exterior, you’d use an EV of -6 to 4, depending on what type of light your subject is under, including moon phases. For night interiors, an EV of 4 to 8 also depending on what type of light is used. If you want to use the manual controls, pick from the chart here that corresponds to your desired EV and f-stop. Exposure value - Wikipedia
That means a value of 1Lux for the directional light “moon” is correct? The problem i have with the current physical lighting setup in Ue4 is, 1Lux gives me no lighting at all in my scene.
I also have a problem with this data charts, i don’t really know how to match the terms in the charts with the editor ones, f number is a clear thing, it’s the f-stop in the editor… values like 1/125, 1/100 or 1/30 are the shutter speed values… but where are the ISO numbers ? I guess they are always the same like the shutter speed? And what is EV ? Exposure Values… Is it the Min and Max Brigthness in the Exposure tab ? or the Exposure Compensation value ?
The chart gives me also shutter speed values like 1 or 2 or 60, without the 1/ , the same goes for 2m, 4m, 8m, up to 256m and so on… how should i use this values ?
And for the simple sunny 16 rule setup like from Daedalus51’s video, Lumen and Candela values are still absolutely not working for me.
1 Lux will only be visible if your exposure is correct. Night time can get into the negative EVs, so 1 Lux will absolutely be visible then. EV is a simplified way of talking about exposure. Just gonna quote myself here cause I’m lazy 
They’re used in the engine by default as the viewport exposure override, unless you enable the extended range option in the Project Settings, which will replace the Min/Max Exposure values for EVs in the Post-Process Volume. Regardless, the Manual mode can achieve identical results, you just have to convert the single EV value to the individual camera settings.
To use the chart for matching EV to manual settings, just set your Post-Process Volume’s Metering Mode to Manual and set the correct values down in the Camera section. Most measurements will be based on ISO 100, that chart included. So because of that, and because the Shutter Speed input is limited to 1/1(1 second), some of the chart is irrelevant. You could do some math to get the required Shutter Speed and F-Stop for a different ISO, but since the manual settings don’t really change anything else it doesn’t matter imo.
Considering that the Sunny 15/16 rule is targeted towards exposing for a subject in direct sun on a clear day, I wouldn’t expect your every day light to be visible then. It’s the same concept of your car’s headlights not visible during the day, excluding the actual light emitting surface since that is always waaaaay brighter. Or your phone screen not being visible out in the sun or it blinding at night.
Sorry to butt in, but I’ve got some questions. I’m not sure how shutter speed works with UE4, generally I’ve heard for video with DSLR cameras, you want to lock the shutter speed to half the frame rate, in order to get an appropriate amount of motion blur. I doubt exposure/motion blur work the same in game engines as they would on a camera (motion blur is a post effect controlled with a value not linked to the camera shutter speed, right?). If shutter speed doesn’t directly effect the motion blur, why would you use that over just changing the iso? There’s no downside to cranking up the ISO since you don’t have to deal with camera noise.
Or am I miss understanding how ISO and shutter speed work in UE4.
I probably just need to play with the camera settings more, I’ve mostly just played with the exposure values and ignored trying to use it like a DSLR.
No I’m in the same boat as you. I don’t see the point in even using the manual options. The cinematic camera/ new DoF are based on physical sensor and lens settings, but I haven’t seen anything where they’re tied together so really I have no idea what else they’d be used for other than people wanting to match a particular setup for a very specific reason.
Right now, I can really only use the manual settings as a sanity check for my values. But currently there’s no way to “eye adapt” between EV values in manual, so I’m forced then to use Histogram/Basic for getting that effect, but those values have no correlation to real life values. I get it - Unreal has to support legacy projects and such, but it’s just not at all intuitive of what values should be. Like Daedalus51, I’d love to have the option of a “Min/Max Aperature/F-stop” adaptation in manual mode. This way I know for sure what a scene should be looking like, since I would have real life equivalent to compare to.
It’s a bit of a process, but you could use the chart on the Wikipedia page I linked above and use the Min/Max EV(once you enable extended range in the project settings) and use EV values based on your desired manual settings at ISO 100. With the correct settings, there’s a very tiny difference between Manual mode and a corresponding EV. I haven’t tried the default min/max settings, but yeah I’m assuming since it’s not with the extended luminance range, the values don’t necessarily line up with the huge range required.
Thanks - I have not turned on the extended range in project settings, I’ll look into that.
But I think the point too overall is that it’s still a bit involved process, when this sort of thing should be a lot easier to work with. Those us hanging out in a photorealism space would appreciate a little more out of the box solution. I really like the idea of using manual because I have real life photographic data and images to compare to, and I’m a bit disappointed that this isn’t a feature in Unreal when I’ve used this sort of system in nearly any other engine I’ve worked in.
First of all thank you for clarifying my points rosegoldslugs!
As k.mermelstein mentioned, things are waaaay to complicated at the moment, on top of that some of the values like lumen are not really working like they should. I hope the next versions of Ue4 will support physical lighting like it should be, you put your real life values into the editor and you get the right lighting result back.
I’m not sure if anyone answered exactly yet why this example doesn’t work so I wanted to clarify. f/8 is not the same as EV100 8. Aperture is only one variable in the equation and EV100 is the total result.
The first image is using fixed exposure of EV100 8
The second image is using 1/125s, f/8, and ISO 100 it looks like.
we can use a calculator to figure out the EV100 number Exposure Calculator
the result of those camera settings is EV100 13, which makes the image appear 5 stops darker.
Maybe it’d be nice to work with variable shutter *or *f-stop (*or *ISO), but the result is always a brighter or darker image and EV100 gives us this in one simple number. Documentation would help