Lighting for Video Games
Adam Alexander talked about some tricks about lighting production in UE4 with instructor Omar Gatica.
Introduction
Hello! I’m Adam Alexander, and I am a lighting artist at Hardsuit Labs. This year I made the switch from environment artist to a lighting artist, and have been working to develop a stronger understanding of what makes good lighting. Titles I have contributed to as an environment artist include Blacklight: Retribution and Tacoma. I recently completed CGMA’s “The Art of Lighting for Games” with instructor Omar Gatica to push my skill set in lighting further. Omar did a great job of laying out a curriculum that stressed lighting theory and techniques that were agnostic of any one game engine and focused on theory and composition. The weekly lectures built upon each other in a way that was both accessible and deep. Each week we were tasked with taking a scene developed by Epic and re-lighting it.
Lighting in Games
Lighting plays a critical role in setting the mood for any given level and showing off the work of all the other art disciplines. Different studios have different approaches to how and when lighting is introduced into the pipeline. At Hardsuit Labs, I generally will do an initial lighting pass at the grey box stage. This pass will include setting up global lights and skydomes and sketching out some early compositions. This early lighting pass can be really useful! Working with environment art and design, I can help define what the focus or mood of any level should be. Lighting is an important tool for directing player attention, so getting this in early helps the whole team. I try to work broadly and quickly; a lot of stuff can still change at this point.
Once environment art and level design have moved on, I usually begin a 2nd lighting pass. The focus here is on polishing the work I roughed in earlier. Meshes now should be unwrapped for lightmap UVs, so I can start dialing in my light bakes. I focus on making sure spaces are readable and interesting. When lighting for games, it is important to remember that gameplay always comes first! There have been several times I will light a high contrast map that I think looks great, only to find that my areas of shadow are too dark to clearly see enemies in combat. It’s important to constantly test your lighting set up as a player would approach it. I usually end my 2nd pass by creating a color grade and setting my post-process effects for the map. After this, I’m almost done! I may still be asked to revisit sections to polish or fix certain areas as a response to feedback from QA or design.
Realism
There have been some very impressive advances in real-time lighting in the last few years. Established PBR material standards and light parameters that have real-world analogies allow artists to have a common foundation to build from. When working on a game that leans towards realism, it is important to adhere to these standards as much as possible. Unreal and other game engines allow you to use a captured HDR image to plug into your sky to replicate real light intensity levels. This, combined with tweaking your bake settings to allow for a good amount of bounce light and good lightmap UV’s can create some stunning lighting alone!
Additionally, knowing when to tweak your piece can actually help sell the realism of a scene. Adding lens imperfections and filmic color grading can make your piece feel more believable, even if they technically aren’t “realistic.” A lot of us are so used to seeing photos or movies that we often feel that games that evoke that imagery feels correct.
Parameters
Lighting can initially feel overwhelming when presented with so many parameters to tweak! There are a couple of points I make for myself to help simplify the process:
- Start Broad, Work Down: This may be obvious to many artists, but starting with your broad strokes and nailing those is really important before digging into details or polish work. I spend a lot of time establishing my global lights and key light in any given scene since this will be the most important lighting contribution to the composition and will form the backbone of my work.
- Less is More: I think in lighting especially, it is important to try to push a small number of lights as far as you can rather than adding a ton of lights right off the bat. It is easier to adjust just a few lights and can help you focus on allowing for spaces of interest and rest in your composition.
- Use Reference: This is another possibly obvious-yet-important tip I have to remind myself! It is critical to study real-life examples of lighting. Keep these open, and not just at the beginning of your project. If I am ever unsure of a particular space I am lighting, I always turn to my reference to study how light would react in a similar scenario.
Post Effects
Things like volumetric fog, sun rays, or atmospheric particle effects can be a ton of fun, but I try to treat them like icing on the cake; they can really help punch up a well-lit composition, but can’t cover up or fix a bad one. I always try to add these last to keep them from being too distracting during my initial lighting pass. Take this with a grain of salt as well depending on the type of game you are making, but I’d caution to use these effects subtly. A lot of times artists (myself included!) can get pretty carried away with these effects at times.
Speed Up
Being able to iterate on your scene quickly is really important, especially if you are using baked/static lighting. This is really where the “Less is More” approach to lighting can help you. If you are adjusting just a handful of lights with each bake, you can move a lot faster than trying to adjust a ton or figuring out which light is contributing what. When working in Unreal, I usually stick to just a preview bake to get a quick idea of what values/hues my bounce lighting will have, with an occasional “medium” quality build to see if there are any shadow errors I should try to fix. When I’m done for the day, I’ll let a production build go overnight.
When working with dynamic lights, it is always good to keep an eye on performance. Dynamic shadow-casting lights can get expensive quickly. Unreal has useful view modes to monitor things like light complexity and overlapping stationary-lights.
Shadows
Getting good shadows is a joy in lighting! When setting up my initial key lighting, I am always looking for interesting cast shadows. Shadows can help your lighting and composition in a lot of ways. Allowing light sources to dip into shadow between each other is a great way to add depth and contrast to your level. Additionally, shadows can say a lot about the type of light environment in your scene; soft, diffused shadows can sell an overcast sky or distant light source, whereas sharp shadows are better suited for a clear sky or very close source of light. Do remember that your game should still be readable even when the player is in shadow though.
Advice
I think there is a lot of value in having a lighting artist do an early pass on a level, as I mentioned before. When beginning on a new map, my first step is to always gather reference and put together a mood board. I look at sources like cinematography, photography, and concept art to start brainstorming composition and palette ideas, while also gathering photos to serve as a reference for details like how light will look from this fixture, or what sort of exposure will be used for this interior, etc. Once I have a good collection of reference material, I will start blocking in my global and key lights. My advice would be to try to spend as much time on these initial steps as you can to ensure that you have a compelling lighting composition with good contrast before diving into polishing out details.
As for additional lighting resources, I highly recommend Omar Gatica’s CGMA class on lighting if that is an option available to you! I also recommend Tilmann Milde’s “Unreal Lighting Academy,” an in-depth video series that covers a lot of the lighting process. Finally, I’d recommend CG Society’s live session with Boon Cotter on “The Art of Lighting for Games”
Unreal Lighting Academy
Boon Cotter’s CG Society Lecture
