Lighting the Scene

It’s time to say, “Let there be light!” Let’s learn how to light up scenes and environments in a practical way. Lighting is a pivotal process and perhaps the most important aspect of any scene. I cannot emphasize this enough – light is everything. As the famous architect Le Corbusier said, “Architecture is the masterly, correct, and magnificent play of masses brought together in light.” So, don’t just read what I have written for you but also experiment on your own. Lighting is a subtle art, and physical values, or correct settings, can only give you a realistic base. Both in real life and in CGI, lighting is not fixed or exact (within a certain range) – the sun, the sky, the clouds, the surfaces, the colors, and the air density are always changing. So, try for yourself and find the perfect balance for your scene.

In this chapter, we’re going to cover the following main topics:

• How to...

Technical requirements

The project files for the chapter can be found at https://github.com/PacktPublishing/Architectural-Visualization-in-Unreal-Engine-5

A general approach to light

The workflow may vary, depending on the person or the situation, but I will describe my usual approach, which is very similar to the light studio setup (which I will explain later in this chapter). You can compare lighting to preparing a cake – you have a core light, which is the base of the cake; some fill light, which is the cream inside providing the main taste and flavor; and finally, an accent or detail light, which is like the sugar decorations on top – they are small and point-focused and don’t affect the substance much, but they help to make the cake visually appealing. So, light your scene in this order and don’t mix up the roles – focus on the first two types, which are enough to make your scene work, and save the accent light for last:

• Core light: This is the main light source of your scene. It illuminates everything and gives the first and most important layer of light. It usually matches the outdoor...

Outdoor lighting

Exterior lighting is made from several actors combined; specifically, you must use some of the following actors:

• Directional Light (also called atmospherical light): This is used for the sun/moon and is the main light source in a scene.
• Sky Light: This captures the background and projects it back as an ambient light. It requires SkyAtmosphere or SkySphere actors to work.
• Sky Atmosphere: This component works closely with the directional light to create realistic or stylized sky and atmosphere effects for different planets and times of day. It also supports ground-to-space transitions with proper curvature and perspective. It has various properties that control the sky and atmosphere appearance.
• Sky Sphere: This is an alternative to Sky Atmosphere but is less commonly used. It is a geometric mesh (spherical or hemispherical) with a sky material applied. You can define the material properties to customize the look of the sky and bind it to directional...

Indoor lighting

Indoor lighting can have different scenarios – the key light can be natural or artificial, and natural light can be direct (illuminating the scene with bouncing rays) or diffused in a Scandinavian style. Each of these scenarios has some variations. If you use path tracing, it is easier to achieve realistic lighting, as the light paths are physically accurate and correct and you don’t need many adjustments. However, if you use Lumen, you have to assist it and its indirect bounces more.

Natural light

The light system is generally the same as what we used for outdoor scenes, with one key difference – the indirect, bounced light. Especially with natural lighting, a key factor is indirect light – light bounces are what define the environment the most and what path tracing aims for. So, when you use path tracing, you don’t need to worry about the light bounces, as they are already physically correct. However, when you use Lumen, you...

Setting up a light studio

One of the most common and effective lighting setups for a studio environment is the three-point lighting configuration. This consists of a key light, a fill light, and a backlight, which are placed around the subject to create a balanced and natural-looking illumination. The key light is the main source of light that defines the shape and direction of the shadows. The fill light is a softer and less intense light that fills in the dark areas and reduces the contrast. The backlight is a rim light that separates the subject from the background and adds depth and dimension.

Figure 6.25: A three-point lighting scheme

To create a three-point lighting setup, you need to add three lights (of course!) to your scene and position them accordingly. You can use any combination of light types, but a typical setup would use a Rect Light as the key light, a point light or a spotlight as the fill light, and another point light or rect light...

Project – lighting an interior

Let’s light up our project of choice together. In the previous chapters, we learned how to import geometries using Datasmith. Now, we have our 3D scene almost ready for lighting. Before starting, I usually turn off all the glass in the scene to let the light pass through. We can do this by either giving them a glass material (which we will learn later), temporarily deleting them (we can reimport them later by right-clicking on the Datasmith actor, choosing reimport, and checking the Re-Spawn Deleted Actors option), or moving them to a temporary level. We can also simply hide them by pressing H, but remember that they will be visible again when we reopen the scene. Another thing to do is to apply a 50% gray material to everything. We can do this by either switching to lighting only visual mode with Alt + 6 or assigning this clay material to every object, but we will cover materials in the next chapter. After that, we can start placing lights...

Summary

We have learned about the importance of lighting and the essential general principles. We have also seen how to light up an outdoor environment using the SkyAtmosphere, SkySphere, and HDRI actors, and how to achieve overcast and night lighting in different ways. Then, we moved on to explore indoor lighting and a light studio setup and how to handle them, using some useful resources from the marketplace. Finally, we applied these guidelines to our personal project. I hope you did the same with your project as well, following the instructions and achieving some decent lighting for yourself.

Now, it’s time to move on and learn about creating and applying materials, which can be seen, by any means, like the solid state of lights: materials serve as the medium through which light becomes tangible and visible.