Ray tracing techniques have long been used in film, television, and visualization for rendering photo-realistic images for a long time but required powerful computers and time to render each image or frame. For film and television, it can take many hours or even days to render out high-quality image sequences, but the final result can create real-life 3D content that can blend seamlessly with real-life ones. For architectural visualization companies, ray tracing has meant creating beautiful renders for the automotive industry or showing what a densely-filled house or office complex could look like when complete all while achieving realistic-looking results.
With the power of Unreal Engine 4 (UE4) combined with Real-Time Ray Tracing (RTRT), it’s possible to create interactive experiences with subtle lighting effects comparable with many offline renderers. Real-time ray tracing makes things look more natural producing soft shadowing for area lights, accurate ambient occlusion, interactive global illumination, and more.
Ray Tracing in Unreal Engine
Ray tracing in UE4 is composed of two techniques:
A hybrid Ray Tracer that couples ray tracing capabilities with our existing raster effects.
A Path Tracer for generating reference renders.
The Ray Tracer enables raytraced results for shadows, ambient occlusion (AO), reflections, interactive global illumination, and translucency all in real-time. It does this by using a low number of samples couples with a denoising algorithm that is perceptually close to the ground truth results. For example, for shadows, this means they will soften based on distance from a receiving surface or light source size and have physically correct contact hardening.
The Path Tracer is an unbiased, physically based path tracer that is good for rendering reference images of your scene. It works similarly to offline renderers by gathering samples over time and, in its current state, is useful for generating ground truth renders of your scene rather than final pixels.