directx

Software:
Unreal Engine 4.25

Steps for activating DXR Ray-tracing in a UE4 project:

1. Project Settings:
   Platforms > Windows > Targeted RHIs:
   Set Default RHI to DirectX 12
   * RHI = Rendering Hardware Interface
2. Project Settings:
   Engine > Rendering > Ray Tracing:
   Check Ray Tracing
   * Requires restarting the editor, and may take a while to load the project afterwards..
   * I’m actually not sure if the reason for delay in re-launching the project is a full re-build of the lighting or compiling shaders..
3. Post Process Volume > Rendering Features > Reflections:
   Set Type to: Ray Tracing
4. Post Process Volume > Rendering Features > Ray Tracing Reflections:
   Set Max Bounces to more than 1 if needed

No DXR Reflections:

DXR Reflections on a GTX 1070 GPU:

 

Related posts:

1. UE4 Light calculation tips
2. UE4 HDRI lighting
3. UE4 – Technical model quality tips