Heightfield GI:
There is info on Heightfield GI in the full release notes of 4.8 under “Lighting” roughly 2/3 down the scrollbar.
LPV update:
The master branch has the latest LPV features which have been checked in around mid May:
Updated LightPropagationVolume (from Lionhead )
- reduced order of SH (faster but a bit more blurry)
- DirectionalOcclusion (disabled by default, can be enabled in PostProcessSettings, affects SkyLight and ReflectionEnvironments but not AmbientCube)
- Material BlockGI feature
- Spotlight support
- Uses AsyncCompute on XboxOne as optimization (order is not optimized yet)