See How to Relight the Dekogon City Subway Train in Unreal Engine

Introduction

Hi! My name is Annelien Heyninck. I'm a Lighting Artist at Playdead in Copenhagen, Denmark. My full portfolio you can find on ArtStation.

Previously, I worked on Avatar: Frontiers of Pandora at Massive Entertainment. I fell in love with video games while playing the Jak and Daxter trilogy with my big brother. I even wrote a fan mail as a kid to Jason Rubin, Co-Founder of Naughty Dog, to thank the team that made these games (funny enough, he replied).

I studied Game Graphics Production at Digital Arts & Entertainment in Belgium and got the opportunity to join the talented team at Studio Gobo for my internship to work on Hogwarts Legacy. This is where I first picked up lighting and fell in love with the craft.

Becoming a Lighting Artist

I studied photography and video production in high school. After finishing my first bachelor's degree, I felt like my creativity was restricted. I then found the major Game Graphics Production at Howest and knew this was what I was looking for. Here I learned 3D modeling, drawing, environment art, and more technical skills like blueprinting and scripting, etc.

I rather quickly noticed that I really enjoyed environment art but more importantly, presenting my work in the best way possible. I started reading about what light is and how it behaves; "why is the sunset red" and "what are these types of clouds". I also started paying more attention to how light behaves in real life by simply observing my surroundings.

Studio Gobo then offered me an internship where I had the opportunity to try both lighting and environment art and develop in whichever path I chose. I loved doing lighting as you work with people from all different departments. This collaboration is so much fun because you both want to push to create the best result with the limitations you have. You also have a lot more creative ideas as a team than alone.

With lighting, you set the look of the game and guide the player, but you also make the players feel the emotions you intend them to feel. After this internship, I was determined to work fully on lighting as this role is where I felt at home. I started working at Massive Entertainment on Avatar: Frontiers of Pandora, where I continued to push my skills and became more interested in the tech behind lighting.

Unreal Engine 5

Previously, I had worked with Unreal Engine 4 and Snowdrop. I find it important to explore the latest real-time lighting tech in the industry and learn about new workflows. Epic enabled "extend default luminance range" in their default projects, supporting the use of physically accurate values. I'm a big advocate of using physical values as a starting point for lighting, and seeing Unreal Engine 5 move more toward this workflow made me eager to learn about the systems behind it.

The first thing you notice with Lumen is that it's very fast, no bake times make the iteration process quick. Lumen enables you to work very efficiently to block out the first lighting look and iterate. There is some concern when it comes to artistic freedom as every object is being included in a dynamic global illumination system, and of course, the fact that real-time GI is quite expensive. Working smart with the lights you have and checking your lighting budget is crucial.

Epic has added an extensive range of Lumen and content debugging tools and visualizers to help with this.

Subway Train Relight

Relighting the Subway Train from Dekogon was perfect for a few small learning goals I set in advance: learn more about post-process color grading and match/play with color palettes. I wanted a small scene to keep the scope contained and not get lost in detail. I used Shotdeck to find my references. It's a great tool as you can filter on colors, settings, time of day, etc., which is a Lighting Artist's dream.

As the scene was made in Unreal Engine 4, I first converted it to 5.3, checked the project settings, and made some adjustments like turning on Lumen. I started removing all the old loose lighting components, reflection captures, fog, post-processing, etc.

Looking at the light sources in the scene and my reference, I wanted the light components to be tied to the light mesh for quick iteration inside the level. To do this, I made blueprints from every unique light where I could control emissives, colors, intensity, range, etc. This made it a lot easier to make big changes in the scene without having to adjust every component on its own.

Setting Up the Marriage Story Lighting Scenario

Once the functionality was there, I adjusted the environment to look more similar to the Marriage Story reference. I used the Unreal Engine modeling tools to remove the glass as this can't be nanite. I changed the adverts on the top to red, adjusted the floor, metals, ceiling, and seats, and added extra light strips.

I measured exposure values in the train station in Malmö and on the train to get real-life references. Then, I used my measured values from the station to adjust the brightness of my HDRI until this was in the range of what I had measured. I did the same for my exposure range inside of the train in the post-processing volume. These kinds of ranges give us a good starting point to create something believable. Then, we can deviate from them to make it look better.

Next, I adjusted the lights to be in the physical value range for these kinds of train lights (3000-4000 lumens) and made them warmer to match the color as seen in my reference. I kept adjusting the environment, materials, and lights while working in this range. Looking at: How bright are the shadows? How strong are the emissive values? Are the whites burnt out?

After I was happy with my lighting, I started lining up the camera to be similar to the reference. While doing this, I kept on adjusting materials and lights to get better results. Iteration and trial and error are key.

For the color grading, I used the "local exposure" to do some tone mapping on the whites and blacks of the scene. I change the temperature and tint to be slightly more warm. I added a bit of blue/purple in the contrast of my shadow to match the shadow underneath the seat in the right corner and tinted my highlights the slightest bit red to get the correct red-ish feeling around the ceiling. I tried to keep my adjustments to a minimum as color grading quickly might become a bit overkill.

TLOU-Inspired Relight

When starting on the TLOU version, I wanted to step out of my comfort zone by using neon colors and trying to match the overall color palette. The blueprints that I previously created made the iteration process very fast. I tweaked the environment a little bit and went over some iterations with the lighting.

I felt like in every reference, there was one red element, so I added one red light in the back of the train to draw attention forward and match the palette. I wanted to incorporate this in a way to draw the attention of the viewer to the back of the train but keep it subtle enough so it wouldn't be disruptive to the overall look like in the references.

Here you can see references with the red element:

The "squint your eyes" test is a great way to check if you see the same colors as in your reference. After iterating on the colors, emissives, and overall ambient, I was ready to move on to color grading.

Below you can see the reference and lighting blurred to check the colors:

For the color grading, I adjusted the local exposure to push the whites down a little bit. I added a bit of blue in the global contrast and took away some contrast in the shadows. Again, I tried to achieve as much as possible with my lights and keep my color grading subtle.

Setting Up the Final Murder on The Orient Express Scenario

The Murder on The Orient Express scenario was the fastest to set up as there were minimal environment adjustments. I added an overcast HDRI where I added controls in the shader to adjust the intensity. I then bumped the value until I measured an exposure value between 10-13.
The HDRIs that I used in this project come from Poly Haven.

Also, for the directional light, I used physical values (between 1000-2000 lux) so we would get ambient light coming in from outside of the train. Adjusting the sky atmosphere to scatter the light more diffusely helped to not get the harsh "directional" but soft diffused light. In real life, a dense layer of clouds would diffuse the lighting coming through, so we need to mimic this in the engine.

After I had my base set up, I tweaked the environment and the lights to be similar to my reference. I made the ground more red and less reflective and tweaked the metals. Afterward, I adjusted the lights to loosely match the reference.

For the color grading, I used the local exposure to bump up Shadow Contrast Scale to brighten up the darks, and I adjusted the color temperature to be a bit warmer. I took multiple shots from all three scenarios, but in the end, one of each says more than enough. Less is more.

Conclusion

I worked on this project some evenings, but in general, I prefer not to put a deadline on personal work. It takes however long it takes or until it no longer brings joy. Personal work should, first and foremost, be fun.

For aspiring lighting artists, I can highly recommend the book "Light for Visual Artists" by Richard Yot to get a better general lighting understanding in different situations. 

The Unreal Engine documentation and YouTube channel are also great because they have a lot of insightful videos where they explain how the tech works.

It's a great starting point! Furthermore, I recommend getting out there and looking at how light behaves wherever you go. Taking pictures is also a great way to build your visual library and learn how exposure works. Having some exposure charts saved as a reference is always handy.

Annelien Heyninck, Lighting Artist

Interview conducted by Theodore McKenzie