Question Lights in HDRP extremely dim except for Main Light

I am working with some lights in HDRP as well as auto-exposure, which I don't fully understand. What is happening is that the main light seems sufficiently bright in accordance with its intensity value, but my point lights and area lights are extremely dim, even when in dark areas, with low main light intensity, and maximum slider value on the intensity. I've found that for a point light's maximum slider of 40 000 Lumens — what Unity says should be a bright exterior light — I get what could pass as candlelight. For something brighter, like a lamp, I must use 400 000, and a ceiling light must have 4 000 000. In all instances, the range was set to 5 meters.

I know this is a bit arbitrary, but I feel like something is severely off for me to have to use these extreme values. Can anyone help me?

 

Compared to what? Sunlight?

Most lights we use in actual real life barely look like they emit any light when in direct daylight.

 

I’m saying that a light which should have looked like a street lamp looked like candlelight, and anything less than extremely high appears to be completely dark. To get a bright light I had to boost the values to ten times what they should have been.

This is also true in dark areas and when the sunlight is very dim. In fact, the light of a light source is no brighter when moved from a bright area to a dark area, even when baking.

 

Candlelight relative to what?

If the answer is nothing then there is something wrong with auto-exposure.

 

Firstly:

Secondly:
If you are working with Physically based units, it's important to understand the relationship between a lights intensity and the exposure of your camera in the scene.

The auto exposure setup in this older version of unity is a little different now with the low and high values, now the basis is to create a clamped range between the EV100 values that the auto exposure will use.



Your brightest and darkest spots exposures levels within any given area or volume should reflect that.

If you know you have an open scene with a clear sunny sky, you can expect the directional light (sunlight) to be around -110,000 lux.

This is around 15EV ( exposure Value)



Each number is representative of a Stop in the industries that use it ( like video and photography)
Each stop/EV is double or half the amount of light exposed

If you had say an outside area and then moving into the room, you will likely want to use a volume to give the exposure range for inside the room and outside.

In general the dynamic range of this exposure is absolutely massive, which is volumes are used to help balance lights and tune areas a little more specifically, rather than suddenly having a wild exposure jump.

You lumens for example is about 4x less in exposure than the directional light example I gave above.

Unity can automatically convert LUX/Lumens/Candella/nits ( screen emissions like a TV or phone) so you can easily take these real world values and plug them into unity.

If I take an example of the room I'm in with the exposure locked to expose my screen inside and go outside now.

I have an exposure range of ~10,000LUX (EV12 )
~60LUX (EV4.6) remembering that each EV/Stop is double of half the light, the lighting outside has doubles 7 times, which is a huge range.

Since I'm inside, I can see my screens and my phone fine. But if I took that outside I wouldn't it'd be hard for my eyes to see without increasing my phone's brightness

Respectively taking a picture of my phone outside you see, well, a phone in need of cleaning but everything is crazy blown out. Cause I've exposed for inside where the first image was taken, this is where auto exposure comes in handy.


So be sure to watch and re watch that video to help understand exposure as well as you lighting sources, like skies, lights, emissions, to help you build a more balanced scene.

Failing that, come back here and post some screens or videos to help is better understand you too!

All the best!

 

The video posted above is excellent. You can also check this presentation for more details.

 

Yeah, I checked out that video several weeks ago but still couldn’t understand. But, you know, I’ve been thinking about it, and I think I may have figured it out: I’ve been looking at the darkness of the inside of the bunker as well as the outside sky, so the outside sky looks about as light as it’s supposed to but the interior lights have to be extremely bright. The exposure level I’ve set it to assumes that we’re compensating for the exterior light levels, but it’s a completely enclosed interior space so it’s dark, so I’ve kind of expected the lights to act normally. Even though they’re in the right darkness, the exposure level is fit for an outside scene. In reality, looking out from a dark space, you’d see a very bright and even overblown view. So I just need to set the lights to what they should naturally be and then manually pump up the exposure until it’s looking right.

I think I’ll also use local volumes for auto exposure because auto exposure is a bit more tricky than manual, but I think I remember some things from that video which should help.

 

I think I understand what you're trying to Percived.

Despite the engine simulating exposure cameras and eyes typically.
It's be not means a perfect representative of them.

It sounds as though you're making some judgements based on being in one space looking into another and not getting the results you're assuming?

Example: standing outside looking into the building with lights and just seeing black or vice versa looking out and just seeing white

This is a difference quite apparent with things like our eyes Vs a camera Vs HDR, where those scenarios would look very different.

Either way, do let us know how you get on

 

Yeah, it’s not a problem with the engine, I had just forgotten how eyes work, and so i was expecting two very different light levels to deliver the same image. Now I’ll set the light levels correctly and boost the exposure (as I said, looking out from an interior room to the outside in real life, the outside would appear very bright).

I think what also made it confusing was that I’m basically covering my outside scene with a layer of volumetric clouds to essentially block out most of the sun, so I wasn’t certain how much light there was supposed to be. I set the sunlight to have a sunset-level of light and then I adjusted the exposure to make it look right.

Long story short, I was working with too many variables — auto exposure, sunlight level, light levels varied by the cloud volumetrics, etc — so I could never have been certain what level of light or exposure should have looked like. Which means anytime I changed one thing it just got more out of alignment.

Now I know how I can fix it, and in the future I’ll be sure to debug auto exposure with both interior and exterior parts of a level.

Thank you very much for all of your help!