[UE4] Building lighting removes/reduces reflections in scene & dims lights (Alot)

DarienTHarvey

Hello I'm working on a new scene for my finals at Uni and I'm just having some problems when building my lighting, 
It's seemed to always act this way and I can never really get around it, of course building in higher quality improves but the results are still extremely taken back from preview with dynamic lights, how can I capture the feel of the lighting in preview with baked lighting? Will it just be down to lightmap res? here are some screens so you can see;
I have reflection captures, and tweaked lightmass settings,
I've had this problem for quite a while Any help or advice would be appreciated, thank you!

Preview - https://imgur.com/4hEU3GP
Built - https://imgur.com/4hEU3GP
Lightmap density - https://i.imgur.com/It8CrcM.jpg
Lightmass Settings - https://i.gyazo.com/eeb0739c4e697ce0b06c5d609202ff5b.png

Preview-
Built
Lightmap Density

Thanks again

Obscura

Use stationary lights instead of static ones.

jakemoyo

Is your viewport exposure set to "in game"? If you go to the settings menu at the top left of the viewport at the bottom there's a setting that says like 'GV-100' etc to lock exposure at a specific setting and  you should have ''in game" checked. Other wise the editor viewport won't match the post process settings you have. 

DarienTHarvey

@Obscura , @jakemoyo Hey Thanks for replying guys, appreciate it tons. I can change to stationary I'm sure that'll fix it cause we wont be baking, the problem would be floating lights having strange shadows, but I could fix that, with that aside, wouldn't my performance see a hit? I'm at fairly low frames atm but attempting to optimize, I'm working solo on the enviro stuff so I've had to do tons. Thanks appreciate it again,


As for @jakemoyo, I've got InGame checked, appreciate the reply though Thanks again.

eCstatic

The reason why you're seeing more reflections in your unbuilt scene is because the engine uses movable lights until you build your lighting. Static Lights are completely baked, which means they wont give any reflections.

Stationary lights aren't that bad for performance because the cascade shadows are still based on a CSM lightmap, but you still want to keep an eye on your attenuation size because if I recall, meshes can only support 4 Stationary Lightmaps shadows at a time.

DarienTHarvey

@eCstatic Thanks dude, I'll play around with it, appreciate the reply. Will try to sort my peformance out, I have a terrible amount of animated actors in the scene so I need to fix that up, so I'll work backwards

leleuxart

eCstatic said:

The reason why you're seeing more reflections in your unbuilt scene is because the engine uses movable lights until you build your lighting. Static Lights are completely baked, which means they wont give any reflections.

Stationary lights aren't that bad for performance because the cascade shadows are still based on a CSM lightmap, but you still want to keep an eye on your attenuation size because if I recall, meshes can only support 4 Stationary Lightmaps shadows at a time.

The 4 limit is with Stationary Lights casting static shadows, otherwise there is no hard limit to Stationary Lights as they're treated like a dynamic(Movable) light. 

Stationary Point, Rect, and Spot lights don't contribute to CSM as that's purely a Directional Light thing. Static shadows from the Point, Rect, and Spot lights are stored in the lightmap, while Dynamic shadows from the Stationary lights are stored in 2 separate shadow maps. 

The main difference you probably see between unbaked and baked is the missing analytical specular from the dynamic lights, like eCstatic said. Static lights can contribute to indirect specular in the form of a specular orb at the location of the light(which can be scaled or removed completely per light), but depending on your positioning and scale of Reflection Actors, the specular orb may not be projected as accurately.

I'd recommend baking on Medium. Preview is great for really quick ideas, but it's missing some elements like multi-bounces(I think? I honestly forgot, I haven't baked in Preview in a long time). You could modify the .ini file to bring some areas more in-line with Medium+, but in my case Medium with near-default settings is far better than Preview with higher quality settings for quick test bakes. Num Indirect Lighting Bounces is fine to leave at 100, but I'd lower the Num Sky Lighting Bounces as that is very time consuming and less likely to show a difference beyond ~5. Your bake time is increased by the super low density of Volumetric Lightmaps too and I believe the Maximum Memory for VLMs needs to be increased as you decrease the Detail Cell value