Real-time ray tracing in Unreal Engine

If you’re in the business of creating architectural visualizations that are physically accurate, 100% believable, and also interactive or immersive, you’ll have heard about real-time ray tracing. 

By tracing the path of light beams from the camera as they bounce around a scene, ray tracing mimics the physical behavior of light in a far more realistic way than the traditional method of rasterization, achieving much greater photorealism as a result. 

At GDC in March 2018, Epic Games unveiled real-time ray tracing in Unreal Engine, opening up a new world of possibilities for architectural visualization.

For archviz specialists used to offline rendering processes that can take hours to render a single frame, the advent of ray tracing in real time is a blessing. Now, it’s possible to create immersive interactive experiences—like VR walkthroughs of a building—that reach a previously unattainable level of realism, while photorealistic renderings can be created in less than a second.

Let’s explore three key areas of lighting an architectural scene in which real-time ray tracing can be the difference between almost believing something is real and actually believing it. 

Shadows

Shadows are the glue that ties the elements of a CG scene together. In addition to adding richness to the shading and tone of a scene, shadows are vital for the viewer to accurately perceive the position of objects in a visualization. 

In a real-time context, the ability to ray trace shadows comes into its own for sun studies, in which accuracy must be spot on to ascertain where shade will fall for a proposed project. Similarly, the photorealism that ray tracing brings to interior designs, with dynamic soft shadows from area lights that capture fine details, can be the key to making a scene wholly convincing. 

Just like in real life, the ray-traced shadow of an object in Unreal Engine looks different depending on the light source’s size and angle. Shadows appear sharper near the contact surface and softer and wider farther away from it. 

As well as being more physically accurate than their depth-map equivalents, ray-traced shadows are easier to use—you just have to flip a switch. Depth-map shadows, on the other hand, need to be optimized to account for the distance of the object from the camera, which involves a painstaking process of tweaking to achieve the best compromise between quality and performance.

Reflections

The ability to create accurate reflections is a critical part of creating hyperrealistic 3D scenes. Ray tracing produces reflections that accurately simulate those you’d see in a real environment—ones that bounce multiple times and create interreflections for reflective surfaces. 

This brings a whole new level of credibility to architectural projects involving surfaces like polished concrete floors, or walls made of metal and glass. 

Similar to shadows, ray-traced reflections have two key advantages over traditionally rendered alternatives: the visual quality is far better, and it’s much easier to achieve them. With virtually no setup required, you can avoid the time-consuming task of reflection probe or plane placement that only provides an accurate depiction from one particular viewpoint and which can be prone to errors. Ray-traced reflections also reflect elements outside the field of view—unlike screen-space reflections.

Sky Lights

As anybody who has seen a particularly spectacular sunset will know, nature provides the best lighting. The ability to accurately mimic sky illumination and light shafts puts a powerful palette of effects at your fingertips that can dramatically enhance the mood and atmosphere of an architectural scene. 

Ray tracing Sky Lights enables you to light your scene using a high dynamic range (HDR) image, producing the subtle, soft effects essential to creating a sense of realism for exterior renderings or interiors with large windows.

Want to harness the power and realism of real-time ray tracing for your own architectural visualizations? Download Unreal Engine for free today. 

 

This article was brought to you by the Team at Epic Games.