(Image rendered with Unreal Engine Path Tracer, model courtesy of Archvyz)



The Path Tracer is a progressive rendering mode in Unreal Engine that can be enabled without requiring any additional setup, the only requirement being a DXR-capable GPU. 



It closes the feature gap of the real-time ray tracing core, including physically correct and compromise-free global illumination, physically correct refractions, feature-complete materials within reflections and refractions, and super-sampled anti-aliasing.



For 4.27, the Path Tracer should be a viable candidate for use in common rendering scenarios, with a focus on AEC, automotive, and product design.



Improvements in 4.27 include:

• Support for all material types except Hair, Eye, and SingleLayerWater.

• Support for refraction and all major blend modes.

• Transmission of light through glass surfaces, including approximate (but not full) caustics.

• Support for most light parameters such as area size, penumbra, attenuation, barndoors, rect light textures, IES profiles, etc.

• Support for nearly unlimited numbers of lights.

• Improved sampling techniques, resulting in less noise in the same amount of rendering time. This is still an ongoing area of research and will continue to improve in future versions of Unreal.

• Support for orthographic cameras.