Entire scene lighting is dark

Development Rendering
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1

I have a scene which models the inside of a tank, I have placed two spotlights in the corners of the cabin and a single point light in the centre, all three are static and have their intensity maxed out at 100000, yet when I build it, the consoles are barely illuminated in the editor or the final game.

A little background that might be helpful:

  • I’m very new to UE4
  • I was handed an existing project with some lighting that worked ok, but the intensity of each light was 10, and the tooltip says 1700 is the intensity of a 100W lightbulb, so that didn’t make sense. The lighting was casting very dark shadows below the controls because all the lights were above the cabin.
  • All these lights were set to ‘movable’ but never moved, so to improve performance, I changed them to static, but after that everything became extremely dark.
  • I added a point light without shadows to act as ambient fill to reduce the shadows, but no matter how intense I made it, it made no difference.
  • I then deleted all these lights and started from scratch with the setup above. While the shadows now fall better, the lighting is overall too dark, despite the lights being maxed out.
  • There are also a number of stationary lights within the cabin that can be turned on and off by switches on the consoles, but I don’t think these should be causing an issue.
  • Due to the nature of the scene, I don’t think I can really share it.

At this point it seems like nothing I do that makes logical sense will work. I wonder if there’s some kind of exposure control system that’s auto adjusting all my lighting beyond my control, but as I’m unfamiliar with UE4 I don’t know where to start.

I looked around the answer hub before I posted, but nothing seems to match my symptoms or referenced something I am unfamiliar with (and therefore don’t know if it’s relevant).

2

After further experimentation, I’ve found that the issue is almost entirely with static lights. When I change the intensity value it looks ok in the viewport, but when I build the light maps it gets really dark. For the short term I am using movable lights (because it can only support so many stationary ones within range of eachother), but this is terrible for performance, so I hope someone can help me.

I was wondering if could be caused by world scale, because I keep finding that I am reaching the limits of attenuation. Unfortunately, I have no idea what scale the models have been modeled in, ad therefore how much they would need to be scaled down. Does it sound like a likely cause?

3

Would you be willing to post some screenshots with the issues you’re having. It’s not always a clear answer this way or that way without a reference, especially if a user is new like yourself that may not know exactly how the system may work.

I’m happy to help regardless, but references make it much easier to diagnose and offer some feedback. :slight_smile:

There are also a number of stationary lights within the cabin that can be turned on and off by switches on the
consoles, but I don’t think these should be causing an issue.

Stationary lights cannot be used in this manner. You would want to make sure that these are set to movable. The problem here is that Stationary lights is a hybrid of Dynamic and Static lighting, which will bake lightmaps to store the lighting and shadow information into a texture that is assigned to your meshes. If you’re going to turn the light on and off the lighting information that is statically baked will not turn off or be removed when the light is not on.

Other things regarding your scene with dynamic vs static lighting.

  • Make sure that you’ve got a lightmass importance volume around your scene.
  • Make sure that you’re static Meshes have a second UV setup for the lightmap otherwise you’ll get lighting and shadowing issues that are baked into the mesh.
  • Once lightmaps are setup for your meshes you’ll probably need to increase the lightmap resolution for some meshes to get better shadowing information baked to the texture

Here is a guide that Eric and I wrote for some common lighting issues and tips for our Wiki that may help in some instances: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

Also any settings you’re using for your lighting and scene can really be helpful as well.

Thank you!

Tim

4

Thanks for your reply.

Stationary lights cannot be used in this manner.

I thought that was exactly what stationary light are for. UE4 documentation:

Stationary Lights are lights that are intended to stay in one position, but are able to change in other ways, such as their brightness and color.
And besides, these lights were working fine, and I’ve had to change them to movable lights because I had more than 4 overlapping. This isn’t the issue.

As I suspected, the scale of the map was completely wrong. I used the starter content chair to judge the right size and it ended up being 0.15 times the size of the original. The intensity and attenuation values are now much more sensible.

I have basically deleted the lights that existed and replaced them with stationary spotlights which generally work OK (I have some issues with correctly illuminating the bulb to make it realistic, but the light itself works fine). I also have a static light above the centre of my scene to add some ambient fill (no shadows). I saw in your guide that skylights are good for this, but it seems I have to have a skybox set up for this, and I don’t need one.

My problem is, when the static light is just placed in the scene, the in-editor brightness looks fine, but when I build the light maps, it becomes extremely dark, no matter how bright I make it. My problem only exists with static lights, but I don’t want to use all movable lights because of performance.

I added a light importance volume, but I have no idea if it’s doing anything (or what it does). I don’t know how to add secondary UV channels in UE4, the bit in your guide seems to refer to a properties panel I can’t find (this goes for the lightmap resolution too).

Please tell me what and where to find any other settings you want to know.
As far as I know, the only thing I changed was auto exposure, and it didn’t work so I turned it back on.

5

Lightmass importance volume is used for focusing lighting photons for static lighting into a core area and anything outside that area will not be as high quality. This is useful for only baking higher quality static lighting in areas that are needed where the player will be. Distant objects will not need high quality lighting since the player will never be close to it.

The second UV channel can be added in either a modeling application or using the generated ones in UE4 via the Static Mesh Editor > Details Panel > Build Settings (This is in the wiki guide)

For the auto exposure when testing lighting issues, it’s best to put a Post Process volume in your scene and set it via the checkbox to Unbound. Then set the auto-exposure min and max value to 1.0. This will not do the auto brighting and dimming that can happen. I also disable lens flare and Bloom to remove any other issues that can get in the way with post process while trying to troubleshoot any lighting issues I have.

6

Thanks for your help, but none of your suggestions worked. It turned out the roughness on all of the materials was 0, so they were reflecting everything and not getting illuminated.