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Unreal Lighting 4.27 - PBR Exposure Workflow - Day Time

Unreal Engine, developed by Epic Games, has continuously pushed the boundaries of real-time rendering, offering cutting-edge tools and features for creating immersive and visually stunning environments. Among its impressive capabilities is the lighting system, which plays a pivotal role in achieving realistic and captivating visuals. Unreal Engine 4.27 introduces significant improvements in its Physically Based Rendering (PBR) exposure workflow, particularly for day-time scenes. In this article, we will explore Unreal Lighting 4.27's PBR exposure workflow and how it elevates the rendering process for day-time environments.

Understanding PBR and Exposure Workflow

Before delving into the specifics of Unreal Lighting 4.27, it's essential to grasp the concepts of PBR and exposure workflow. PBR is a rendering technique that mimics real-world materials' behavior, ensuring that light interacts with surfaces as it would in reality. It considers various material properties like albedo, roughness, metalness, and normal maps to produce lifelike visuals. Exposure, on the other hand, relates to the control of light and dark areas in an image, akin to a camera's exposure settings.

The PBR exposure workflow allows developers and artists to maintain consistency across different lighting conditions and times of day. It enables them to create scenes that respond dynamically to changes in lighting conditions while adhering to realistic physical principles.

Enhancements in Unreal Lighting 4.27

Unreal Engine 4.27 introduces several noteworthy enhancements to its PBR exposure workflow, focusing on day-time scenes. These advancements enable creators to achieve unparalleled visual fidelity and realism in their projects. Let's explore some of the key improvements:

Improved Sun Positioning System

The new Sun Positioning System in Unreal Engine 4.27 offers enhanced accuracy for real-world sun positioning based on geographical location and date. Creators can input latitude, longitude, and time of day to precisely position the sun in the sky. This feature facilitates the creation of accurate day-time lighting scenarios, making it easier to match the virtual environment with the real world.

Sky Atmosphere Update

Unreal Engine 4.27 includes a revamped Sky Atmosphere system that generates stunningly realistic skies. The new system simulates the scattering of sunlight, resulting in dynamic changes in color and intensity throughout the day. Artists can easily adjust the atmospheric qualities to achieve the desired mood and ambiance in their day-time scenes.

Realistic Cloud Rendering

Cloud rendering has also received significant attention in Unreal Engine 4.27. The new volumetric cloud system allows for the creation of dynamic and realistic cloudscapes that interact with sunlight and cast convincing shadows on the ground. This feature adds another layer of realism to day-time environments.

Ray Traced Global Illumination (GI)

Unreal Engine 4.27 introduces Ray Traced Global Illumination, which dramatically enhances the accuracy and realism of indirect lighting. With ray tracing, light bounces more accurately off surfaces, resulting in more natural and convincing day-time lighting scenarios. This addition greatly reduces the need for manual lightmap tweaking, making the workflow more efficient and artist-friendly.

Virtual Production Tools

Unreal Engine 4.27 brings improvements to virtual production workflows, empowering creators to blend virtual and physical elements seamlessly. The ability to interactively light virtual sets with real-time feedback allows for rapid iteration and experimentation, resulting in more refined and believable day-time environments.

Best Practices for Day-Time Lighting

Creating compelling day-time lighting in Unreal Engine 4.27 requires a combination of technical knowledge and artistic sensibility. Here are some best practices to keep in mind:

Study Real-World References

Observing and studying real-world day-time lighting scenarios is crucial for achieving authenticity in your virtual environments. Pay attention to how sunlight interacts with different materials, the quality of shadows, and the overall color palette during different times of the day.

Optimize Ray Tracing Settings

While Ray Traced Global Illumination significantly improves lighting realism, it can be computationally intensive. Artists must optimize ray tracing settings to strike a balance between visual fidelity and performance, especially for complex day-time scenes.

Use Lightmass Importance Volume

To ensure accurate and efficient indirect lighting computation, consider using Lightmass Importance Volume. This volume specifies the areas that require detailed indirect lighting information, preventing unnecessary computation in other parts of the scene.

Experiment with Atmospheric Effects

The updated Sky Atmosphere system and volumetric clouds offer a wide array of possibilities for atmospheric effects. Experiment with different settings to create the desired mood and lighting conditions for your day-time scenes.


Unreal Engine 4.27's PBR exposure workflow has taken day-time lighting to new heights, providing creators with powerful tools to achieve stunningly realistic and visually captivating environments. The improvements in sun positioning, sky atmosphere, cloud rendering, and ray-traced global illumination have enhanced the efficiency and quality of day-time lighting creation. By following best practices and combining technical knowledge with artistic flair, developers and artists can leverage these features to create truly breathtaking day-time scenes in their projects. As Unreal Engine continues to evolve, we can look forward to even more groundbreaking innovations that will further push the boundaries of real-time rendering and interactive storytelling.

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