I created new empty UE4.23 preview 6 scene and checked all of variables default values in not modified scene. Here what I got.

r.RayTracing = 0

r.RayTracing.AmbientOcclusion = 1

r.RayTracing.AmbientOcclusion.EnableMaterials = 0

r.RayTracing.AmbientOcclusion.EnableTwoSidedGeometry = 0

r.RayTracing.AmbientOcclusion.SamplesPerPixel = -1

r.RayTracing.CacheShaderRecords = 1

r.RayTracing.DebugDisableTriangleCull = 0

r.RayTracing.DebugForceBuildMode = 0

r.RayTracing.DebugForceOpaque = 0

r.RayTracing.EnableMaterials = 1

r.RayTracing.ExcludeDecals = 0

r.RayTracing.ForceAllRayTracingEffects = -1

r.RayTracing.GlobalIllumination = -1

r.RayTracing.GlobalIllumination.Denoiser = 1

r.RayTracing.GlobalIllumination.DiffuseThreshold = 0.05

r.RayTracing.GlobalIllumination.EnableTwoSidedGeometry = 1

r.RayTracing.GlobalIllumination.EvalSkyLight = 0

r.RayTracing.GlobalIllumination.MaxBounces = -1

r.RayTracing.GlobalIllumination.MaxRayDistance = 999999988484154753734934528.0

r.RayTracing.GlobalIllumination.NextEventEstimationSamples = 2

r.RayTracing.GlobalIllumination.SamplesPerPixel = -1

r.RayTracing.GlobalIllumination.ScreenPercentage = 100.0

r.RayTracing.GlobalIllumination.UseRussianRoulette = 0

r.RayTracing.InstancedStaticMeshes = 1

r.RayTracing.InstancedStaticMeshes.CullClusterMaxRadiusMultiplier = 20

r.RayTracing.InstancedStaticMeshes.CullClusterRadius = 10000

r.RayTracing.InstancedStaticMeshes.Culling = 0

r.RayTracing.InstancedStaticMeshes.LowScaleCullRadius = 1000

r.RayTracing.InstancedStaticMeshes.LowScaleRadiusThreshold = 50

r.RayTracing.Landscape.DetectTextureStreaming = 1

r.RayTracing.Landscape.LODsUpdateEveryFrame = 0

r.RayTracing.NormalBias = 0.1

r.RayTracing.PSOCacheSize = 50

r.RayTracing.Reflections = -1

r.RayTracing.Reflections.DirectLighting = 1

r.RayTracing.Reflections.EmissiveAndIndirectLighting = 1

r.RayTracing.Reflections.HeightFog = 1

r.RayTracing.Reflections.MaxBounces = -1

r.RayTracing.Reflections.MaxRayDistance = -1.0

r.RayTracing.Reflections.MaxRoughness = -1.0

r.RayTracing.Reflections.MaxUnderCoatBounces = 0

r.RayTracing.Reflections.MinClearCoatLevel = 0.01

r.RayTracing.Reflections.MinRayDistance = -1.0

r.RayTracing.Reflections.ReflectionCaptures = 0

r.RayTracing.Reflections.SamplesPerPixel = -1

r.RayTracing.Reflections.ScreenPercentage = 100

r.RayTracing.Reflections.Shadows = -1

r.RayTracing.Reflections.SortMaterials = 0

r.RayTracing.Reflections.SortSize = 5

r.RayTracing.Reflections.SortTileSize = 64

r.RayTracing.Reflections.TestPathRoughness = 1

r.RayTracing.Shadows = 1

r.RayTracing.Shadow.MaxBatchSize = 8

r.RayTracing.Shadow.SamplesPerPixel = 1

r.RayTracing.Shadows.EnableMaterials = 1

r.RayTracing.Shadows.EnableTwoSidedGeometry = 1

r.RayTracing.SkyLight = -1

r.RayTracing.SkyLight.DecoupleSampleGeneration = 1

r.RayTracing.SkyLight.Denoiser = 1

r.RayTracing.SkyLight.EnableTwoSidedGeometry = 1

r.RayTracing.SkyLight.MaxRayDistance = 10000000.0

r.RayTracing.SkyLight.SamplesPerPixel = -1

r.RayTracing.SkyLight.Sampling.StopLevel = 0

r.RayTracing.StochasticRectLight = 0

r.RayTracing.StochasticRectLight.IsTextureImportanceSampling = 1

r.RayTracing.StochasticRectLight.SamplesPerPixel = -1

r.RayTracing.Translucency = 0

r.RayTracing.Translucency.DirectLighting = 1

r.RayTracing.Translucency.EmissiveAndIndirectLighting = 1

r.RayTracing.Translucency.HeightFog = 1

r.RayTracing.Translucency.MaxRayDistance = -1.0

r.RayTracing.Translucency.MaxRefractionRays = -1

r.RayTracing.Translucency.MaxRoughness = -1.0

r.RayTracing.Translucency.MinRayDistance = -1.0

r.RayTracing.Translucency.PrimaryRayBias = 0.00001

r.RayTracing.Translucency.Refraction = -1

r.RayTracing.Translucency.SamplesPerPixel = 1

r.RayTracing.Translucency.Shadows = -1

r.RayTracing.UseTextureLod = 0

ShowFlag.RayTracedDistanceFieldShadows = 2

ShowFlag.RayTracingDebug = 2

Now I have number of questions - general, about default values, what exactly do some of variables. Since I can't find answers just by google it I need some technical specialist answers. Or if this "Rendering" thread is not the right place for such questions maybe someone can redirect me to right place.

So lets go on with questions.

General questions.

1. For variables like r.RayTracing.Translucency, r.RayTracing.SkyLight value is boolean 1 - 0? Some of variables have value 1 (enabled) some 0 (disabled) some -1. What mean this -1 if variable type is boolean so what mean "-"? Is it -1 because feature still not enabled somewhere in PostProcess?

2. For Distance type variables -1.0 mean that value is unlimited ( "-" ) and variable type if float ( ".0" )

3. For Max/MinBounces type variables = -1 mean that bounces number is unlimited or it because as I asked before for features which is not enabled bounces values =-1?

Values and description questions.

01. r.RayTracing.CacheShaderRecords = 1 What exactly do this cache record? Is it boolean 0 - 1 or some range of integer values variable ? What does different values?

02 r.RayTracing.ForceAllRayTracingEffects = -1 What exactly do this variable? Is it boolean 0 - 1 or some range of integer values variable ? What does different values?

03. r.RayTracing.GlobalIllumination.DiffuseThreshold = 0.05 What exactly do this variable? Is it float between 0 - 1?

04. r.RayTracing.GlobalIllumination.EvalSkyLight = 0 What exactly do this variable? Is it boolean 0 - 1 or some range of integer values variable ? What does different values?

05. r.RayTracing.GlobalIllumination.MaxRayDistance = 999999988484154753734934528.0 Is such default value is OK?

06. r.RayTracing.GlobalIllumination.NextEventEstimationSamples = 2 What exactly do this variable - cant see noticeable visual difference?

07. r.RayTracing.InstancedStaticMeshes.CullClusterMaxRadiusMultiplier = 20, r.RayTracing.InstancedStaticMeshes.CullClusterRadius = 10000 , r.RayTracing.InstancedStaticMeshes.LowScaleCullRadius = 1000, r.RayTracing.InstancedStaticMeshes.LowScaleRadiusThreshold = 50 What exactly do this variables? Which values is better for performance?

08. r.RayTracing.NormalBias = 0.1 What exactly do this variable? Is it float between 0 - 1? Is it affect performance?

09. r.RayTracing.PSOCacheSize = 50 What exactly do this variable? Which values is better?

10. r.RayTracing.Reflections.ReflectionCaptures = 0 What exactly do this variable? Reflection captures in ray traced scene.

11. r.RayTracing.Reflections.SortMaterials = 0, r.RayTracing.Reflections.SortSize = 5, r.RayTracing.Reflections.SortTileSize = 64 What exactly do this variables? Which values is better?

12. r.RayTracing.Reflections.TestPathRoughness = 1 What exactly do this variable? is it boolean 0 - 1?

13. r.RayTracing.Shadow.MaxBatchSize = 8 What exactly do this variable? Which values is better?

14. r.RayTracing.SkyLight.DecoupleSampleGeneration = 1 What exactly do this variable? is it boolean 0 - 1?

15. r.RayTracing.SkyLight.Sampling.StopLevel = 0 What exactly do this variable? is it boolean 0 - 1 or some range of integer/float?

16. r.RayTracing.StochasticRectLight.IsTextureImportanceSampling = 1 What exactly do this variable? is it boolean 0 - 1?

17. r.RayTracing.Translucency.PrimaryRayBias = 0.00001 What exactly do this variable?

18. r.RayTracing.UseTextureLod = 0 What exactly do this variable? is it boolean 0 - 1? Why by default its disabled?

19. ShowFlag.RayTracingDebug = 2 Is it boolean 0 - 1 ( if yes why value =2) or some range of integer? How to use this debug? I tried to change values and nothing happened.

20. r.RayTracing.DebugDisableTriangleCull = 0, r.RayTracing.DebugForceBuildMode = 0, r.RayTracing.DebugForceOpaque = 0 How to use this debugs and do I need to use it?

Thanks for reading and any informative answers.

## Comment