Breakdown: UE5 Abandoned Observatory Cinematic Relighting Studies

Introduction

Hello, everyone. My name is Hugo Lafont, and I'm currently a Lighting Artist at Ubisoft Montpellier. I've always had a passion for video games, and I've been lucky enough to work on some of my childhood favorites, such as Prince of Persia and Star Wars. When I'm not playing Dark Souls or taking screenshots for references, I like to take the time to create visuals on Unreal Engine.

In this breakdown, we'll be looking at my entire creative process on my latest personal project, covering points ranging from the importance of reference work, preparing the scene beforehand, my creative process itself, the importance of composition, and the link between digital art and other artistic mediums. I'll also be sharing the plug-ins I've been able to use, as well as links to articles, videos, and books that I think are mines of knowledge.

Given that this project is made up of 6 different moods, we'll focus on the most interesting points of each of them, and in particular on the fact that 3 use the default version of Unreal while 3 others use the Ultra Dynamic Sky plug-in.

The Auge Observatory Project

This project came about following an offer from an outsourcing studio to give me access to their website so that I could relight a large number of stages. My previous project was an indoor lighting project, so this time, I wanted to do an outdoor project with a strong focus on mood and on having several times of the day. After hours of research, I ended up choosing the Auge Observatory environment from Dekogon because it offered a great view and high quality on subjects that make all the difference, such as modeling, the environment, and materials.

It's important to analyze these points as thoroughly as possible because materials that don't properly reflect light or an environment that's too noisy will significantly reduce the quality of your work, forcing you to correct these problems when they weren't the original intention of your project.

Getting Started

Understanding the importance of reference work was one of the things that helped me improve the most after I left school, and since then, I've tried to spend as much time as possible on it so that I don't wander off and have to think about my intentions when I'm creating. I sometimes try to categorize them according to what I'm looking for (practical lights, mood, composition, quality goal, colors), but this time, it was a bit more organic.

However, I did take the time to have a main reference image for each mood, which helped me a lot to get a clearer idea of the palettes to use and the ratio of light in the shadows and their colors.

As I said earlier, this project stems from a desire to work over several hours of the day, and I found a lot of inspiration in similar lighting studies by Arthur Tasquin, Lucas Uny, and Rain Yan. However, references can come from any field, and I've got into the habit of alternating between 3D, 2D, photographic, and video game inspirations – the art world is a virtuous circle, and it would be a shame to deprive ourselves of all that it has to offer!

Although the number of moods to be produced was never fixed, I settled on several basic times: dawn, dawn, morning, blue hour, night, and finally, to take advantage of the mountainous setting, aurora borealis. I also took references for less realistic moods, but these will be used in another project!

UE5 Project Setup

Now that we have an environment and an idea of what we want to do, it's time to make sure that everything is properly calibrated in the engine. One of the first things to do when opening a new scene is to make sure that Lumen is activated, to do so, go to the project settings in the Rendering tab. Here check that Lumen is used as the Dynamic Global Illumination Method and that Virtual Shadow Method is selected.

If you have a graphics card that supports this, you can select Support Hardware Ray Tracing and Use Hardware Ray Tracing when available (as my graphics card is not powerful enough, I was unable to activate it here). This will improve quality in areas such as GI and reflections.

Another important point is to make sure (if the scene needs it) that Nanite is activated and that the meshes used have it activated. The best way to see this is to open the previews and look for red meshes in Nanite's Mask view. 

For a red mesh in the Nanite preview, this can easily be corrected by turning on Enable Nanite Support directly on the mesh. Ensuring that all meshes use Nanite has often helped me to improve the performance of the scene I'm working in, and I recommend checking this.

It's also important to take the time to do the same with Lumen by looking for invisible meshes in the Lumen Scene.

An invisible mesh on the Lumen view can be corrected by ensuring that the Mesh Distance Field Resolution Scale of the offending mesh is not set to 0. If that's not enough, you can also activate Generate Mesh Distance Field.

If you're working with really small objects near the camera that are black in the Lumen scene (and that you want to be used in Lumen), increasing your Lumen scene detail in a post-process volume will allow Unreal to include them in the Lumen scene.

Project Structure

The basic idea of the project was to create one lighting situation per night for a week before giving myself more time to polish. As working on many lighting scenarios simultaneously can be complicated, one of the easiest ways to fix this is to work with sub-levels. This allows you to make compartments with a main scene and child scenes called sub-levels into which you put all your lights.

The advantage is that you can activate your different lighting scenarios with one click and rename each of these levels to find your way around. As I knew that the environment wouldn't change, all the meshes are contained in the main scene, except for the lighting props and VFXs, which are duplicated in each of the lighting scenarios.

Camera

Now that the basis of the project is in place and we've familiarised ourselves with the scene we're working in, it's time to position the main camera. As I knew I wanted to work on exterior lighting, strong moods and on the time of day, I chose a distant camera; showing the whole building with a mountain to emphasise the feeling of depth; with a quarter composition, separated by the central tower. As for the format, I opted for 2.39.1 to give it a more cinematic feel and take full advantage of the environment available to me.

Lighting

When the main camera is positioned, the very last step is to remove any lighting actors and replace them with default actors to start from a neutral base.

When I approach a lighting situation, I first position the sun, then the sky, and finally the fog. The idea is to create the bulk of the composition and decide on the overall mood quickly before working on a smaller scale. Having a good result with just these elements is a good sign of the final quality of the project.

I like to see an image as a painting, simplifying its shapes to decide on the shapes of the light and, therefore, the composition of the image. Playing with shapes, light, and colors is, in my opinion, the fundamental point of lighting because it is these points that, once combined, direct the viewer's eye.

In the same way that references can come from any medium, we can also borrow from their rules and ways of seeing an image to think about our compositions and colors; painting, photography, and film have been around for longer than we have, so there is a huge amount of reference and knowledge to take. Also, we can use many of the techniques used in these fields, and you will see that this is the case in my work.

From a technical point of view, this project is based on the use of the basic UE actors and the Ultra Dynamic Sky plug-in, Lumen, fog added to fog cards, and occluders; I'll go into this in detail after talking about the different settings produced.

Default Unreal Actors

Having said that, let's take a look at some practical examples of how this translates into 3D. And with the actors present by default in Unreal.

For sun placement, iteration is your best friend at the start of a project, a good thing to do is try many sun directions until you find one that works for you. Once I've found the position, I like to never touch it again.

For the sky, I try to see it as two distinct categories: the color and the way it shapes the image. For this project, I preferred to use sky atmospheres combined with Sky Light, although I could also have used HDR backdrops, which offer good flexibility and a wide variety of rendering options, whether for realistic HDRI, which you can find on sites like Locations Textures or Poly Haven, or more fantastic things like on Velarion's marketplace.

For the 3 images above, I mainly played with the Rayleigh scattering and Mie parameters to modify the interaction of the sun with the atmosphere because the default color of the atmosphere was often close to the one I wanted, apart from a few details. 

As for the Sky Light, I play a bit more with its color and intensity, even if it means losing any notion of coherence. There's no real science behind my iterations, I just keep iterating until I get what I like.

One thing that's very important when you're working on an outdoor scene is the clouds. Because in these projects a very large percentage of what you have on screen is the sky, so it's important to make sure that it's visually interesting.

In these lighting scenarios, I used UE's default volumetric clouds with relatively few modifications because, in 2 of the 3 cases, they would be largely hidden by fog. Fortunately, their positions always worked very well with the shape I wanted to give the background.

Fog always plays a very important role in my work, creating a real compositional support for me while at the same time supporting the mood. It calms down the noise in an image and helps to prioritise information (I imagine that working on Prince of Persia The Lost Crown didn't help me to think differently).

I'm constantly working with volumetric fog activated so that I can better integrate my practical lights, especially here where I knew I was going to use the windows and street lights as props lights.

In order to get a thicker, more intense fog, I changed the Sky Atmosphere Ambient Contribution Color Scale value beyond 1 rather than changing its density or Falloff, as this gave me more control over its placement to keep the building out of the fog. 

When I finished my project, I found out about the Screen Space Fog Scattering plug-in, which takes the rendering of the default one to a whole new level. I wasn't able to use it here but I'd still recommend taking a look at it!

I use fog cards a lot in outside scenes, especially those in the Easy Fog plug-in. Having fog cards gives me greater control over my composition and also helps me prioritize the depths of the image.

Below, you can see the importance of fog cards. On the first screen, I've highlighted the different areas where I've used fog cards to show the thought I've put into their placement. Depending on the context, I like to use these cards as a sort of vignette. As for the depth, I didn't want to just drown the background in a uniform mass but rather create 2 levels. What's more, using cards helps certain meshes to stand out in the distance, as in this case with the mountain, which creates depth even without additional lighting. 

Another alternative to fog cards, depending on your needs, is fog materials, which are materials applied to a mesh that can influence the volumetric voxel grid. For a good demonstration, I recommend this video:

Ultra Dynamic Sky

As I said earlier, this project was based on using UE's default actors in 3 situations, whereas I used the Ultra Dynamic Sky plug-in in the other 3 situations.

This plug-in excels at customizing the sky while maintaining a dynamic rendering. It's perfect for outdoor environments and especially for time-of-day processing. Its interface is complex to get to grips with for the first time because everything is brought together under the umbrella of the actor’s plug-in, but luckily, on my side, I work daily with a system that is extremely similar, allowing me to put into practice the things I've learned at work.

The plug-in is divided into several categories: sun/moon, sky, fog, and rendering. Knowing that I wanted to work with TODs, the first thing I did was to choose a time that seemed consistent with the setting: 00:00 for the aurora borealis, 06:40 for sunrise, and 18:12 for sunset. Changing the time is extremely easy and makes it easy to have a first iteration of the scenes.

Then, it's all a question of fine tweaking, positioning your sun to get the best composition, placing clouds, and calibrating your fog (once again). I know that the interface doesn't make this easy, but it's important to take the time to do so. If you're not familiar with all the parameter names, you can easily access the documentation. 

Each of these 3 lighting scenarios uses very different situations, so I'm going to try and cover the most relevant points using examples and some tips that I've used on each of them.

For the Dawn setting, the bulk of the work involved modifying the colour of the sky. I wanted to have a fairly light natural gradient starting from a violet and ending on a paler pink. To achieve this, I tweaked the colour settings in the sky atmosphere tab as well as those in the sky glow.

Even so, the sky still seemed too empty, but the almost nocturnal mood allowed me to play with the silhouettes of the clouds and the presence of stars and the moon to enhance the composition. UDS allows you to activate the presence of the Moon, which affects the atmosphere by lighting it up, but also to modify its shape. And the same goes for the stars
There's no real black magic behind all this, the important thing is to explore the opportunities offered by the tool until you get what you want.

As my PC wouldn't let me shoot video at more than 15 fps, I decided at the start of the project that there would only be still images (art is born of constraints and dies of freedom, after all). One of the very practical things here is that you can freeze the clouds and play with their position once you've decided on the cloud cover. This means you can manage your composition perfectly.

The Aurora setting uses a very similar logic. However, one obvious thing makes the difference here: the Northern Lights. Once again, this is a very simple thing to create. The actor has a section dedicated to it, and all you have to do is modify the parameters until you get what you're looking for.

We can divide the parameters into two parts, one more focus on the artistic direction, and the other on their quality.

Now for the Dusk setting, this uses more of the plug-in's default values, so the moos and colors, when set to 6:20, were almost perfect. However, I boosted the Sky Light enormously to get the lightest shadows possible because I wanted to stick to my main reference while still getting very intense sunlight.

Here, as in the other two scenarios using UDS, I added a UE default Directional Light to the one in the plug-in to better control its position and the softness of its shadows. To do this, I reduced the intensity of the sun in the plug-in to keep a very soft light that complements the Sky Light while adding shadows.

Right from the start, there was this desire to give light a shape in this scenario. Whether it's in paintings, films, or my main reference, I always like it when the subject is lit by a light with almost geometric shapes.

To do this, I borrowed a technique from the world of cinema: lights occluders, also known as flags. Whether it's to give a shape to the light, as in this example, or to darken areas that are too noisy (like the trees here), occluders are an essential tool. It's a technique used constantly in Prince of Persia to ensure that the game playground is correctly lit, as we had the advantage of 2D gameplay with a camera fixed on 2 axes without X rotation (without which the player would have quickly realized that the shadows were not physically correct). 
To create light occluders, simply generate a generic 3D cube and, if you want to place some in the frame, deactivate the Visibility settings and tick Hidden Shadow.

The double sun technique was also used in the two darker moods; the Sky Light wasn't enough to do what I wanted; it flattened the shadows too much, whereas I always wanted to keep more information in those areas, so having an independent directional light allowed me to bring out more details the flat surfaces.

Props Lighting

Now that we've seen the different ways of setting up the basics of outdoor lighting, let's move on to some more micro subjects, starting with props lights. Often, I don't like to justify the physical existence of some of my lights, but using props lights (such as the street lamps or windows in this case) can provide quite pronounced contrast. What's more, trying to find a light source in the main subject of your scene helps to bring the composition back to it because you'll be inserting the highest points of contrast there.

Having a building as massive as the observatory is the ideal playground for experimenting with lots of different sources. We can add street lamps, wall lights, or even illuminated windows to add very strong lights that won't break the realism of an image. Although floating lights are fun to use, having a very intense, unjustified spotlight will break the immersion.

For the window material, I was able to use a Master Material already present in the project. It was perfect because it had a cube map, giving an impression of depth on each of the windows. All I had to do was modify the tiling, the emissive, its color, and its intensity to get believable windows.

For the positioning, I imagined the separation of the rooms inside and positioned the lights where I imagined a room to be in order to keep things credible.

I created new versions of the materials and lighting props for each scenario before I had control over their colors and the intensity of the emissive.

I think it might be interesting to look at the light emitted by these windows because here, as everywhere else, I've cheated on how to achieve the result. Here by creating several area lights, some projecting harsh light onto the architecture from the inside to recall the intensity level of the emissive material and others to bring about a gentle propagation of light, as if to recall the bounces of light.

One of the advantages of the lighting world is that (apart from optimization) it's the result that matters. We're here to produce a beautiful image and it's important to detach ourselves from reality to do that.

Unjustified Lights

I always use unjustified lights to improve the composition of my image, it's something that my lead taught me. Thinking about the value and colors over the whole image, whether it's the lit areas or the shadows, is crucial. An environment should be treated like a character's lighting, with its mains lights, fill lights, and why not even its rims!

There's no one particular type of light that's dedicated to a specific type of lighting for me, it's all situational. However, I particularly like working with Rect Lights and Spot Lights in my projects. As for the colors, although I use them, I think that the color theory is a cultural thing, so as a European, I just rely on my personal feelings to direct my colors towards the feeling I want to convey.

Lighting Tips

I wanted to cover a few more points by talking about techniques that I haven't necessarily used. We've already seen how to occlude light in film and photography, but we can also see how to reflect it. Thanks to Lumen, you can reproduce this effect using white cubes to project light or black cubes to absorb it.

Once again, I strongly recommend taking an interest in other artistic fields in general. For the world of cinema, this video is a good introduction and shows the use of what we have just seen.

A good alternative to reflectors is to create planes or other coloured emissive mesh, which reduces the complexity of lighting while retaining control of the colour and intensity emitted. I learnt this technique while watching the breakdown behind the latest Lord of the Fallen, and I have to admit that it's extremely useful for imitating the rendering of lights without incurring the cost. You can use the same logic as for occluders to make them invisible.

Post-Processing

I've gotten into the habit of tackling post-processing at the very end of my process since I've been in the video game industry. Post-processing affects all the pixels on the screen, so it inevitably affects the characters as well as any gameplay-related elements, and when you want to support their legibility, it's important to make sure that they don't blend in with the background. So, making sure you have sufficient contrast levels before this pass helps enormously.

But that doesn't mean you have to do without the tools you have. In this project, the post-process plays an essential role. I played a lot with color grading, modifying the colors of the shadows, mid-tones, and highlights, as well as their contrast and saturation. I also used an LUT on each of the different scenarios to support the contrasts. Sometimes, our ideas have to change, and using the post-process on my personal projects allows me to operate without having to modify all my parameters.

The use of color temperature was very useful in giving the image the cold feeling I wanted to convey. It's something I use in almost all moods to calm the very warm color of the brick.

However, all the scenes are treated differently, so sometimes the differences are much smaller. Like fog, vignettes are my best friends. I use them very often because it's a simple technique for focusing the composition.

Export Screenshots

Now that we've seen the whole creation process, I think it's worth looking at a few tricks for getting good screenshots. I always use Unreal's default High Resolution Screenshots system for still images. To ensure the best quality, I make sure I change the screen percentage to 100. To increase the resolution of the captures, I've used a screenshot size multiplier by 2 on the export window. It's up to you to find the value that best suits your needs.

Important Console Commands

r.Streaming.PoolSize: Allows you to allocate a greater proportion of resources to rendering textures, among other things. Here, I've set it to 4000 (4Gb) to ensure that all the textures are fully rendered (despite the high-performance cost). 

r.Tonemapper.Sharpen: If you like to use high-pass filters in your external retouching, this command allows you to do that directly in the engine, which is very useful for increasing the detail of textures that can get lost. I use it quite often, but as this environment is quite noisy, I never went above 1.1.

External Tools

For a few more tweaks, you can take your screenshots to Photoshop and retouch them locally. I do this to improve my compositions and modify things like saturation, contrast, and color locally without affecting the whole image like a post-process. To do this, I use adjustment layers with masks. Although it's not possible to do that in a game, here we're working on our portfolio so we can afford it.

I often use the Camera Raw filter to have control over all the parameters from the same window. Although I haven't done it here, you can easily apply these parameters to a LUT by duplicating the layer to find these same parameters directly in the engine. 

One thing I like to do (and recommend) is to test your work on different screens to check that it looks good whatever the setup. As each person has a screen with a different saturation, colors, and contrast, it's a good way of making sure that you're not working only with the awareness of your own calibration.

So You Want to Be a Lighting Artist

If you're interested in lighting or you're simply a lighting artist just starting out in the field and want to develop your skills, the first thing I recommend you do is read the book Light and Colors by James Gurney. Although this book is by a painter, the vast majority of the points covered can be translated into the digital world. Understanding how light is emitted and how colors propagate will enable you to approach your work differently by sharpening your eye. After all, what we do is nothing more than to paint light!

One point I've discussed throughout this interview is the importance of drawing inspiration from mediums other than digital art. So, you shouldn't be afraid to go to museums, watch films that appeal to you because of their style or lose yourself in photographers' galleries to get as much inspiration as possible. 

On a more practical note, what I recommend when you want to develop new skills is to start with small-scale projects and develop new working techniques for each of them. The idea is to focus on particular points in order to concentrate your efforts on the same task and reproduce it more effectively in the future. When I was an environment artist, I tried not to learn more than two new techniques per project (learning to sculpt on ZBrush, how to make vegetation, etc.), and I think this is something that can be useful in all areas. Why not do a project where you come and concentrate on interior lighting, focusing on making the place explorable in gameplay mode; another project where you learn (as here) how to use a new plug-in and where you experiment with composition or develop your skills in using colors?

Working on a Lighting Project

If you're interested in working on a project similar to mine, and to sum up the interview, I'd advise you to do several things.

First of all, ask yourself what kind of project you want to produce, will it be indoor or outdoor, will it be stills or video, what will your subject be and how will you make it shine? Also make sure you know what type of scene you're getting into and the constraints it represents. For example, in this case, it was a pre-made outdoor scene, and it was obvious that the sky was going to have a huge influence on the quality of the image. So I had to explore the options available to me and go for the ones that best suited my needs, i.e., how to iterate quickly on the colors, the time of day, and the composition. Once you have an idea of the purpose of your project and the basic material you're going to light, it's crucial to take the time to do some pre-production work. Creating a file of references, like the one I made on PureRef, gives you an overview of the work in advance and will prevent you from getting lost and embarking on a time-consuming project that may never see the light of day. 

Once you start working on your environment, take the time to do things. Working on your portfolio should be a pleasure because here, you are able to express yourself fully without time constraints. In the past, I've too often imposed a deadline of a few days or a few weeks on myself because I thought that recruiters would notice me for that, whereas the quality of the final product comes first.

If you're feeling stuck, turning to the Internet can help you see how other people work and the tools they use. The art world is a supportive environment in which you'll never be alone, and it may seem obvious but don't hesitate to contact people, whether to ask them questions about their work or ask for feedback on yours, because it's easy to lose your objectivity after many hours of looking at the same pixels. Our world is full of good people who are happy to help others, and knowledge is more accessible than ever.

Some extra links to valuable resources: Arthur Tasquin's Breakdown: The Science Of Lighting, Rain Yan's The Changing Seasons: UE5 Feudal Japan Cinematic Lighting Studies, and Karim Yasser's lighting hacks video:

Thank you for taking the time to read me! It was a pleasure to write this article and to take the time to share and reflect on my creative process. I hope I've taught you something and motivated you to fire up your favorite game engine or 3D software and do some lighting.

If you'd like to contact me, you can do so on LinkedIn or by email.

This is the end, see you soon for more projects.

Hugo Lafont, Lighting Artist

Interview conducted by Gloria Levine