How to Convey Moods in Nature Using Unreal Engine

Atmosphere and mood play an important role in any 3D composition. Here are a few useful tips on how to use Unreal Engine to achieve this.

How do we convey moods by using colors, lighting, as well as other essential tools and features in Unreal Engine?

In the first part of the series, we detailed the most important steps for creating stunning compositions in my natural environment project. Let’s consider the same project as base here, and I’ll talk about some tips to study the mood before adding your lighting to the scene.


Color Scheme and Theory for 3D Renders

Lighting is vital in any composition but, first, we have to consider the colors. What do I mean by colors in this context? Well, whether you’re planning a natural environment or a sci-fi one, you should be aware of your color scheme.

A color scheme represents the set of colors appearing in a scene as a whole. This creates a first impression and should convey the right mood for the scene itself. When you decide to add color to a single object or light, you’re trying to create a link to the rest of the environment.

My advice is to think about the mood before setting up your lighting. In my case, I wanted:

  • A relaxing place to showcase.
  • A precise time of the day.
  • A natural lighting with a color temperature around 5500 Kelvin.
  • The choice of green and blue as color schemes that are considered soothing and relaxing at the same time.
Relaxing Color Scheme
The sense of quietness created with neutral lighting and cool colors (green and blue).

At first glance, the environment creates a sense of quietness and peace. The presence of cool colors and hues—such as the green of the vegetation and the blue of the sky—create the overall color scheme.

Also, the lighting is neutral, which is perfect to capture a precise time of day. In this case, it could be around noon, where the sun is high and the color temperature is around 5500 Kelvin. There’s no presence of dominant colors and everything looks clean and pleasing to the observer.

As you know, color temperature changes during the day. The following image gives you an indication of the different color temperatures we can use.

Color Temperature
Color Temperatures from sunrise to sunset. We’re positioned around 5500 Kelvin. Image via Lumistrips.

Here’s another example with some differences:

Realistic Hut
A brighter, more saturated render conveys energy and positivity.

As an artist, I always spend time studying the compositions that I make. First, I’ll decide which subjects to frame and what color scheme I want to preserve. In the “hut shot,” the intention is to convey peacefulness, and the tones are variations of green and blue, as shown in the first render.

However, this time, I introduced some brown colors and hues to break up the scene and communicate the presence of other natural biomes. I was inspired by the video game Red Dead Redemption 2 to develop the environment and the lighting system.

The scene is also more saturated, vivid, and brighter than before, which conveys energy and positivity by making the observer interested in the exploration of the environment. The hut color follows the hue of the terrain in foreground and is an example of connection to the rest of the environment.

Let’s compare the previous example with a new one:

A sunny day compared to a different atmosphere (purple haze).

This time, we have a different mood in the scene. I decided to tone down the vivid and brighter colors we had before by adding a cooler hue (a pinky and purplish atmosphere in this case). You can notice the presence of purple haze in the background where we have the mountains.

Apart from a different time of day, the whole composition determines a different mood. The cool tones convey a calming, relaxing effect, and sometimes a sense of melancholy, especially as we observe the mountains.


The Role of Fog and Sky

If you look at the previous renders, you’ll notice how the presence of fog and sky is quite important in our compositions.

A bit of science for you. Photons don’t decay in nature, as they’re able to travel light-years. But, when they generally interact with small particles, atmospheric fog, etc., they’re scattered or lose a bit of their intensity. You’ll notice this behavior especially in the mountains.

My advice on using fog:

  • Represent the aerosol content (dust, moisture, fog) of the air and weather.
  • Create a sense of depth in the composition.
  • Hide farther details.
  • Add drama or mystery to your composition.

On the other side, the sky is extremely important in conveying mood as well. Here’s what I mean.

Sky-Dome
The sky-dome quickly changes the mood in the scene.

I chose a sky-dome and rotated it in order to have the overcast part visible in the composition. The sky itself darkens the scene, making it more dramatic, and indicates that a thunderstorm (or rain) is about to appear.

The sky alone is powerful in determining the right mood of the scene. If we had made the sky clear (no clouds), the mood would have quickly changed, even with a few tweaks in the lighting system.


Thinking Like a Painter

Sometimes, we want to act like real painters and consider art history as a precious resource. Impressionism can give us cues in creating our scenes—details, sensations, and visual perceptions conveyed by the environment during the day, and with lighting studies of nature, atmosphere, and sky.

In the next render, I wanted to capture the essence of the environment as a real painter or photographer would.

Painting-Inspired
This scene is reminiscent of a painting enriched by details and vegetation.

The presence of flowers are position closed to the camera and sun, in the upper-left corner, bringing vibrance and energy to the scene. The sun enhances the sub surface scattering effects on the grass when lit from behind.

The sky makes the sun appear and creates a subtle bloom effect (a sort of glow of the bright light bleeding beyond its borders). We want to add more brightness to the left, rather than the right-side of the shot.

Overall, the contrast of the left and right parts, the importance of vegetation (like the flowers), as well as the point of view, bring a more natural look to the shot—they capture details but the elements create a sense of harmony.


A More In-depth Look at Unreal Engine

At the beginning of this article, I described what allows artists to convey the right mood. Nevertheless, we haven’t talked about Unreal Engine yet. And, in particular, which tools you can utilize.

In Unreal Engine, the lighting system is nice, and our lighting setup—apart from the types of lights used—takes advantage of other features that improve the results.

In this next section, we’ll talk about two practical tips:

  • Two environment lighting examples for the current project with the tool (actors) used in Unreal Engine.
  • The use of Dynamic Sky.

There are many ways to create a robust lighting setup. For outdoor scenes with a visible sun, as in our case, you have to think about how light works in real life.

Sunlight travels through the atmosphere before hitting the ground. There, it encounters particles of different sizes and light is scattered—phenomena like Rayleigh and Mie scattering occur.

Rayleigh is responsible for the blue sky where small particles block and scatter the blue wavelength, letting the red through. At a lower altitude, the presence of bigger particles like aerosol (dust, droplets, soot, etc.) tend to scatter all the wavelengths, which is why we have white/gray clouds (Mie scattering).



Earth's Atmosphere
Photo showing the atmosphere around the globe. Image via Science News for Students.
Rayleigh and Mie
Rayleigh scatters the blue wavelength, while the Mie scatters at a lower altitude and isn’t very wavelength dependent. Image via mkrgeo blog.

The light hits the ground and bounces, reflecting in different ways. Some of the light is even reflected back into the atmosphere.

At lower altitudes, there might be the presence of fog, depending on the weather conditions and other factors. In our project, I wanted to include a subtle layer of fog, visible at a distance, caused by a tiny amount of haze and turbidity in the air.


Daytime

Let’s see the actors involved in Unreal Engine.

  • Atmospheric Fog: The component creating a sort of scattering effect through the atmosphere (as explained above). This adds a bit of turbidity in the air (to avoid having the air completely rarefied). This is the first element that improves the realism of the scene. The sky shows some haze, which is also present at the horizon. Near the sun, you’ll notice a white glare effect due to the Mie and the presence of particles.
Scroll to see with and without atmospheric fog.
  • BP_Sky: A blueprint Sky is an actor used to add a sky-dome with a proper HDR image. The default parameter—“Use Skylight?”—allows you to utilize the sky contribution to illuminate the scene.

Here’s an example of what I mean. The skylight illuminates the scene, as it would in real life.

Scroll to see how the skylight contributes to lighting throughout the scene.
  • Exponential Height Fog: Sometimes, you want to add a bit of fog at a lower altitude because water vapor, in some conditions, condenses near the ground, creating small water droplets in the air. In Unreal, there are two important parameters—the Fog Inscattering Color that essentially sets the color of the fog in the environment and the Directional Inscattering Color, which controls the scattering color for the directional light only (in this case, the sun).

They can be used together to obtain interesting effects:

Scroll to see the amount of fog in each scene.
  • Directional Light: As the name suggests, this light is used to represent the sun.

Apart from the generic parameters—intensity, light radius, color temperature, etc.—you should be aware of other important settings:

  • The Mobility that needs to be set as Movable, meaning that lights can change over time and shadows are dynamic. Realtime shadows are meant to be used more and more as they don’t require any baking process, but adequate hardware resources.
  • On the other hand, the Cascaded Shadow Maps section will improve the quality of the dynamic shadows near the camera. Plus, it also considers the presence of shadows at long distance but with less resolution for performance purposes.
Scroll to see either just the skylight or the skylight with the sun.

Nighttime

There are other lighting setups you can build in Unreal with almost the same elements.

For a night scene or a more artistic render, you can use the following actors:

  • BP_Sky_Sphere: Creates a sky-dome which allows you to automatically change the time from day to night by controlling the Sun Height. It’s really interesting because it has some pre-built settings with stars, clouds, etc., which can be extremely powerful if you don’t have an HDR image.
  • Sky_Light: Responsible for taking into account the light coming from the BP Sky Sphere to be projected on the scene (similar to the previous option “Use Skylight?” in BP_Sky). In order to see the effect of this actor, you have to use the option Recapture. Furthermore, to control the intensity of the ambient light (skylight) on the ground, you can use the parameter called Intensity Scale.
  • Exponential Height Fog: The same as before but, in this case, used to create a more artistic look with a bluish tint.
  • Point lights: To fake ambient light in dark areas or to emphasize a part of the scene (in the window of the hut, for instance).

Dynamic Sky

The previous setups are good in many situations, but you might want a dynamic sky for a more immersive experience, or to create an animation timelapse.

Unreal Engine relies on a powerful plugin called Hemisphere Skies. The plugin comes with two sky examples, but you can separately purchase other skies if needed. The idea behind the Hemisphere Skies plugin is quite simple. Just take a look at the documentation and you’ll be ready to work with dynamic skies.

Here’s how simple it is to set a new HemisphereSky actor in your scene:

  • Install the plugin.
  • Enable extended exposure in your project settings.
  • Remove all Skylight, Directional Light, Sky Sphere, Atmospheric Fog, Sky Atmosphere, and Exponential Height Fog actors in your scene.
  • Click on the Hemisphere (blue icon) in the toolbar and voilà! Your actor is ready to work!
Hemisphere Skies Plugin
The Hemisphere blue icon and the HemisphereSky actor with its components.

You’ll be surprised by the components automatically added to your HemisphereSky actor. They have many similarities to the actors we described before. In this case, we don’t need to add them separately as they’re packed together. We have SkyLight, ExponentialHeightFog, Directional Light (SunLight), and so on.

The PostProcessVolume is nice for adding custom Post Processing Effects like color grading, exposure, blooming, etc.

The single components are already set up for you. You can change some parameters if you like, but most of features are managed in the details of the HemisphereSky actor.

Here’s what you can change from the interface:

Hemisphere Skies Settings
The settings for the HemisphereSky actor.

The Sun, Sky, Fog, and Post Process rollouts are self explanatory, thus I won’t be spending time on that. However, I’ll spend a few words on the Timelapse section, which is the star of this plugin!

The Timelapse rollout has the following parameters:

  • Selected Timelapse used in your scene: Here you can choose the sky you want for your scene.
  • Time: A simple slider from 0 to 1, telling how your sky changes over time. A specific time is a frame (photo) of your current sky.
  • Auto Play: If enabled, it animates the Time slider, producing the movement of the sky.
  • Playback Type: Can be forward or backward.
  • Loop: When you finish your animation, you can choose whether to stop the animation (don’t loop), to enable a loop, or to play a loop with a ping pong effect.
  • Play in Editor: Simply enables or disables the sky animation in the viewport.

Finally, here’s an example of dynamic sky with timelapse that I created:

An example of a dynamic sky with timelapse.

Part Two Conclusion

In the first part, I gave you some ideas about how to convey the right mood in a scene. In particular, we explored concepts like color schemes and color temperature. We talked about the role of fog and sky in a composition. We concluded that art history is a valid subject to take inspiration from.

In the last part, we described more technical aspects in Unreal Engine by focusing on particular actors involved in the creation of a natural scene (both daytime and nighttime).

Finally, I showed how dynamic skies allows for more possibilities while showcasing your work.

In the next and final article, we’ll explore the role of the cut scenes and how they can tell a story. Stay tuned!


A few more design ideas to keep that inspiration rolling:

The post How to Convey Moods in Nature Using Unreal Engine appeared first on The Shutterstock Blog.

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