Documentation covers significant improvements to GPU Lightmass for global illumination baking, alongside enhanced ray tracing capabilities. These features made 4.26 particularly attractive for architectural visualization and film production.
: A new component that interacts with Sky Atmosphere and Sky Light to create realistic or stylized skies with real-time lighting and shadows. unreal engine 426 documentation exclusive
Perhaps the most visually striking feature introduced in 4.26 was the production-ready Hair and Fur system. The documentation provides extensive coverage of the Asset Groom Editor for setting up properties, LOD generation, and compatibility with features like Depth of Field and Fog. Perhaps the most visually striking feature introduced in 4
UE 4.27 introduced several QOL changes, but it also introduced new physics quirks and build issues for consoles. 4.26 was the final version of UE4 that received a full, uninterrupted year of hotfixes without the "beta" stench of early UE5 migration tools. and Hidden Architecture
Navigating the Unreal Engine 4.26 Documentation: Exclusive Features, Production Pipelines, and Hidden Architecture