Realtime GI lighting seems much brighter in HDRP

[dgoyette]

I’m in the process of converting my project over to HDRP. Relatively smooth sailing so far, but I’m finding that with Realtime GI enabled, I’m seeing a lot more indirect lighting bouncing in my scene than before. It’s so much light that it seems to completely wash out any shadows the objects might cast. I’m curious if anyone can suggest something I might be doing wrong.

Here’s a visual comparison. The first is the game running under the built-in renderer. In this scene there are two spotlights hanging from the ceiling:

Note that there are shadows on the ground.

Now here is the same scene, this time under HDRP. Forgive the few objects I still haven’t fixed up yet:

Some objects are significantly brighter now, though others (the large door on the left, the metal boxes) are noticeably darker. This is with Realtime GI enabled, and a few light probes around the room.

Now, here’s the same scene under HDRP if I disable Realtime GI, and crank the intensity of the two spotlights:

Notice that you can see the shadows again.

Some stats for the three screenshots, to summarize:

• Screenshot 1: Built-in renderer, Realtime GI enabled, spotlights each at intensity 4
• Screenshot 2: HDRP, Realtime GI enabled, spotlights each at intensity 400 lumens
• Screenshot 3: HDRP, Realtime GI disabled, spotlights each at intensity 12000 lumens

There is no baked lighting in the scene. Any indirect lighting adjustments are set to 1.

The obvious issue is that in Screenshot 2, with Realtime GI enabled, I’m getting a huge amount of bounced light, and I don’t understand why. It wasn’t like this under the built-in renderer. It’s so much bounce light that it’s washing everything out.

I’m not sure what else to mention, but here’s what the light looks like:

Any thoughts on why I’m getting so much indirect light in my scene?

Thanks.

[dgoyette]

The only way I’ve been able to address this has been to lower the Indirect Intensity to something very lower, like 0.01:

This results in roughly the contribution that lights had in the built-in renderer.

So, is indirect lighting really 100 times brighter in HDRP? Or do I likely have something set up wrong?

[dgoyette]

I’m still trying to understand this lighting issue, which seems unusable with the default settings. I’m still assuming I’m doing something wrong. I’ve just tried this out in 2018.3 Beta, hoping it would look better, but the result is the same: With Realtime Lighting enabled, pretty much any light will completely blow out the whole area. As a simple test, I created ProBuilder box and put a spotlight in it. Then the only difference between the following two images is turning Realtime Lighting on:

With Realtime Lighting turned off:

And now with Realtime Lighting turned on:

Again, if I lower “Indirect Intensity” in the scene to about 0.05, or lower the light’s Indirect Multiplier to 0.05, then the lighting tones down so you can see textures again. But are we expected to always turn things down to such a low value to get reasonable results?

What am I doing wrong here?

[SebLagarde]

Hi,

sorry haven’t read the whole thread so I may have miss information but in 2018.3 regarding lighting only the static lighting from the progressive lightmapper is correct (and follow inverse square attenuation).

real time enlighten don’t support inverse square falloff currently and is not compatible with color temperature and don’t correctly handle a divide by PI also. So it is expected that working with it is difficult.

There is work plan on this but it will arrive in 2019.1 and 2019.2 sadly.
This is an unfortunate situation… I have no advice regarding this other than using static GI for now…

[dgoyette]

Thanks for the reply. So, let me see if I understand. In the built-in renderer, my light’s Intensity was 1 “unit”, while under HDRP it’s 600 “Lumens”. The Realtime GI is therefore 600 times brighter, as though I had set the light to 600 “units” under the built-in renderer?

Or maybe not. But the big take-away is that HDRP doesn’t properly support Realtime GI yet, but with plans to support it in the relatively near future?

My workaround so far has been to lower the indirect multiplier of my lights themselves, rather than lowering the scene’s indirect intensity, as the latter results in realtime emission not having any meaningful impact, while the former still yields good real time emission.

[hippocoder]

Ensure your mask materials / pbr stuff is sorted out as well - can lead to horror story lighting like in your above shots if you don’t keep tabs on it. Follow the artist guide for HDRP on blog if you haven’t already.