Lighting Tweaks for More Impressive Scenes
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Lighting Tweaks for More Impressive Scenes
19 April, 2018
Environment Art
Environment Design
Interview

Allen Zayden showed the way he did the relighting of the amazing environment created by Wiktor Öhman. Learn about the different lighting techniques in UE4. Also check out today’s Epic Games stream devoted to lighting!!!

Introduction

Hello! My name is Allen Zayden, I’m from Minneapolis in the United States. Currently, I’m the Lead 3D Artist at Frontwire Studios, volunteering my time on Galaxy in Turmoil. Previously I worked at AECOM as a Junior Visualization Specialist working on projects in VR and general visualizations.

Lighting experiments

I’ve been helping the Art Director at Frontwire Studios with lighting our levels recently and was pushing him to upgrade our engine from 4.17 to 4.18 due to the lighting updates.

The recent lighting experiments are due to having internal server maintenance at the studio, so I decided to take the downtime as a chance to test out my ideas of lighting our interior levels via emissive materials rather than dozens or hundreds of point and spotlights. The results went far better than I could anticipate!

For years I’ve been wanting to get V-Ray quality results with lighting in a game engine, the recent update with the volumetric lightmaps and multi-bounce improvements definitely helps bridge the gap that existed between 3d Graphics software and your traditional game engine.

I’ve found lighting fascinating since I was a child, my mother is an electrical engineer so I’ve found light and how it’s used in art and the scientific properties behind it fascinating my whole life. Depending on the direction of a single light for example, you could make a character look angelic, mysterious, or dangerous. You can turn a fairly normal or even somewhat bland 3d scene into something visually exciting just by how your lights are placed and what the focus is on.

Deus Ex environment

For Wiktor Öhman’s Deus Ex environment, I had removed all the original lights Wiktor put in, including the directional light and skysphere that it was hooked up with. The only light in the level after this is a skylight I’ve placed in. Everything is essentially lit via emissive materials through the newly added radiosity solver after baking the lights which I’ll get into further detail below.

Placing a skylight in the scene is used mostly for shadow tinting (shadow casting needed to be turned off on the skylight, volumetric scattering intensity boosted up to 4.0 can also help slightly, but it depends on the interior) working with the exponential height fog’s volumetric fog. If you leave “Override Light Colors with Fog Intensity” checked off (as is the default) you can easily tint the volumetric fog/shadows (and it appears the AO? I might be mistaken regarding AO but in my tests it appeared to affect AO coloration as well) in the interior with the skylight color.

Details

As stated above, the volumetric fog works in conjunction with the skylight here. In my recent re-lighting tests, I’ve incorporated volumetric fog in all of them. First and foremost- because I just love it, but it also adds a bit of a kick to the interior. Personally, I increase the fog density over the standard range which stops at 0.05 to 0.1 or slightly higher depending on what I’m looking for and then adjusts it further with the “Static Lighting Scattering Intensity.” I don’t touch the albedo, emissive, or extinction scale in this scene but I have in others, although adjusting the albedo does the same thing visually as the skylight color. Since there’s no directional light in this scene, turning on or off the “Override Light Colors with Fog In-scattering” does nothing- but in my re-lighting of Liam Tart’s Scifi Bunk Room, I had kept it disabled so I’d have full control of the color of the volumetric fog. I also occasionally adjust the Fog Height Falloff to 2.0 from the default of 0.2 but didn’t do that for this scene.

Materials

The emissive materials are the really awesome part of this whole lighting breakdown! Unreal Engine 4.18 added multi-bounce indirect lighting. In this scene, the emissive intensity in the material is set to 15, but 5-10 is usually plenty in my previous tests and re-lighting examples where I also used emissive materials to dictate the lighting. Upon checking on “Use Emissive for Static Lighting” I set the emissive boost from 1.0 up to 5.0 for most assets using emissives for lighting. If the material is predominantly emissive, say a cube that’s just an emissive material, setting it at 1.0 or 2.0 can generally work fine. If it’s a series of small emissives, say little emissive windows on a ship exterior for a sci-fi scene, setting it upwards to 50 might work better. Periodically checking the level in detailed lighting mode or lighting only is a better way to really see if the emissive material boost is set too high or too low. Another amazing feature of this is when you use volumetric fog it properly interacts with the emissive materials! So if you’re looking for some ambient lit colored fog, this is a fairly nice way to do it and in my tests pretty cheap too. For the reflections, I kept it mostly the same as I got it from Wiktor’s original scene. The quality is set to 50 and roughness to 0.6 as is the default. Setting the quality up to 100 appears noisy and you end up losing most of the nice chrome-like reflectance. Color Grading also played a major role in the feel of the scene. The most important alteration was the highlight gain adjustment along with the global saturation, gamma, and contrast. The LUT is also critical in this scene to get the blue-orange contrast. For the LUT I just used the Strong Blue Tint LUT from the Amply LUT Pack by Amplify Creations on the Unreal Marketplace.

Setting up for games

Using this lighting setup for a game I think works really well. First of all, you eliminate the need for virtually all fill lights. Keep in mind using emissive materials for your lighting will create soft shadows but it doesn’t allow the character to cast shadows. What I mean by this is, say you have your player character running past some emissive materials bouncing their photons around producing light and shadow. It will appear to more or less light and shadow your character akin to an actual light source, however, you’ll notice your character does cast shadows themselves. So I’d personally use this in conjunction with physical lights like a spot or point light. If you’re already using a directional light, this may or may not be enough for the player’s shadow casting. The biggest benefit I’d have to say is eliminating potentially hundreds of lights in a level where you’d have numerous fill lights that aren’t casting shadows and multiple shadows casting lights with a small attenuation radius so you don’t get the warning for having over 4 overlapping stationary lights that cast shadows which then convert one of them to a dynamic moveable light.
 

I would also like to thank Kirill Tokarev for giving me the opportunity to share my work, and for all the inspirational articles that 80 Level has provided for the gaming industry and our artistic processes.

Allen Zayden, 3D Artist and Visualization Specialist

Interview conducted by Kirill Tokarev

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