Practical usage of Lightmass in Architectural Visualization (Kenichi Makaya, UE4 Lightmass Deep Dive)

Lightmass Deep Dive #2 Practical usage of Lightmass in Architectural Visualization

Architectural Visualizer Kenichi Makaya

Profile • Creating architectural perspectives since 2008 as a freelancer. • Started creating architectural content with UE4 soon after its release.

CASA BARRAGAN

Scene Data Used in this Presentation Casa Barragan Forum Sample Reference Resources House of Mexican Architect, Luis Barragan https://forums.unrealengine.com/showthread.php? 88952-Lets-make-Lightmass-EPIC-(and -understandable)&p=413678&viewfull=1#post413678

Test PC Specs • CPU • Memory • GPU Core i7 4790K 4.0GHZ x 4 core 16GB GTX770

Presentation Theme

Improving Lightmass Details and Addressing Artifacts

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Production Settings with Normal Lighting Layout

Final Settings

Rendering Soft Indirect Lighting

Likely differs from optimizations for games

Procedure 1. Selecting Lights 2. Setting up the Scene 3. Testing Lighting 4. Lighting Sketch (Esquisse) 5. Final Lighting 6. Lightmass Deep Dive

1. Selecting Lights

Four Types of Lights: • Directional Light • Point Light • Spot Light • Sky Light

Light Mobility: Static or Stationary?

Designed mainly using Directional Light and Sky Light But encountered problems....

Insufficient diffraction of Indirect Light

Sky Light can calculate only one bounce of Indirect Light

Drawbacks of Sky Light Lighting from Sky Light only

Drawbacks of Sky Light Insufficient diffraction of Indirect Light

Because no photons are emitted

Emit Photons Emit No Photons • Directional Light • Point Light • Spot Light • Sky Light

Need Soft Indirect Lighting from the window

Spot Light placed in window Static Spot Light Source Radius 200

Both Light and Shadows are hard

Used Koola-style Bounce Card

What is a Koola Bounce Card? Supports multiple bounces of Indirect Light while enabling Soft Lighting.

Koola Bounce Card Size 200 x 200 cm

Static Spot Light Source Radius 200

Main Lights Used in Casa Barragan • Directional Light Stationary • Sky Light • Koola Bounce Card Static Static Spot Light Decided to try the above settings first

2. Setting up the Scene

Lightmass Importance Volume Placement Specifies Area for Volume Lighting Samples

Lightmass Portal Specifies Area of Focus for Final Gathering calculations

Improved Skylight Quality With Portal

Improved Skylight Quality Without Portal

Improved Skylight Quality With Portal

Improved Skylight Quality Without Portal

Reflection Capture Placement Without Reflection Captures, results are poor due to Skylight reflection

Reflection Capture Placement Better to temporarily place Reflection Captures to approximate the final image

PostProcess Off • Auto Exposure • Causes exposure changes • Bloom • Overly bright screen and poor results • Screen Space Ambient Occlusion (AO) Difficult to tell if results are from the light bake or from AO

Compress LightMaps off UMAP size 63MB UMAP size 90MB Not sure whether noise is caused by insufficient number of samples during light bake or by compression noise. Be careful of increase in Light map size!

3. Test Lighting

Adjusting Lighting Balance Preview or Medium Lighting Quality is good enough

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 0 2m54s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 1 3m41s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 2 3m35s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 3 3m46s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 5 3m39s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 10 3m55s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 20 3m42s

Adjusting Num Indirect Lighting Bounces Num Indirect Lighting Bounces 100 3m31s

Adjusting Num Indirect Lighting Bounces • Differences are practically unnoticeable at around 10 • Almost no influence on build time

4. Lighting Sketch (Esquisse)

Need detail in the Lightmaps How?

1. Higher Lightmap Resolution LightmapResolution = 512 LightmapResolution = 64 • Details lower than or equal to minimum texel of light map can not be captured

2. Decrease Static Lighting Level Scale (Decrease RecordRadiusScale of Irradiance caching) StaticLightingLevelScale = 1 StaticLightingLevelScale = 0.1 • Details smaller than RecordRadius can not be captured

This means... 1. Decrease Static Lighting Level Scale until required detail is present 2. Increase lightmap resolution until detail can be captured

1. Setting Static Lighting Level Scale

Details in photograph Details of shadows and bokeh around here need to be reproduced in our scene. Reference source http://motokimokito.blogspot.jp/

Static Lighting Level Scale = 1 (Default)

Static Lighting Level Scale = 0.5

Static Lighting Level Scale = 0.2

Static Lighting Level Scale =0.1 We’ll use this!

At this stage, do not worry about noise. Check the Detail.

Setting for Final Lighting Build

Reference source: http://motokimokito.blogspot.jp/ Is sufficient detail reproduced?

Influence on Dynamic Meshes Static Lighting Level Scale 1.0 Static Lighting Level Scale 0.1 Be careful! Decreasing Static Lighting Level Scale increases Volume Lighting Samples．

2. Setting Lightmap Resolution

Light Map Resolution 32

Light Map Resolution 64

Light Map Resolution 128

Light Map Resolution 256

Light Map Resolution 512

Light Map Resolution 1024

Detail of Direct Shadows Tempted to increase resolution to prevent jaggy shadows

Detail of Direct Shadows Used Cascaded Shadows instead to avoid increasing resolution

Lightmap Resolution was set

Is it enough to simply increase LightMapResolution for each mesh?

Adjusting UVs for Lightmaps is still required

Adjust to appropriate padding Padding between UV islands for Lightmap = 0

Adjust to appropriate padding Padding between UV islands for Lightmap = 4

64 4 Adjust padding to 4 texels

Adjusting Indirect Lighting Smoothness

Static Lighting Level Scale = 0.1 Indirect Lighting Quality = 5 Medium Decided on the above settings

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 2.0 33m28s

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 2.0 33m28s

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 2.0 33m28s

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 2.0 33m28s

Indirect Lighting Smoothness = 0.5 28m56s

Indirect Lighting Smoothness = 0.8 32m55s

Indirect Lighting Smoothness = 1 29m46s (Default Value)

Indirect Lighting Smoothness = 1.2 33m22s

Indirect Lighting Smoothness = 1.5 28m58s

Indirect Lighting Smoothness = 2.0 33m28s

How Indirect Lighting Smoothness works More Detail Improved Smoothness Increased Noise Less Detail Value Decreased 1.0 Value Increased

Basically, Indirect Lighting Smoothness=1.0 is acceptable.

The following values may be also be acceptable: If detail is important: 0.8 If smoothness is important: 1.2

5. Final Lighting

Addressing artifacts

Before that,

What are the Lighting Quality and Lightmass settings doing? In BaseLightmass.ini, we already mentioned: • Static Lighting Level Scale, • Num Indirect Lighting Bounces, and other settings including: Indirect Lighting Quality, Indirect Lighting Smoothness

Configuring BaseLightmass.ini

BaseLightmass.ini is in C:¥Program Files¥Epic Games¥4.12¥Engine¥Config

; These are tweaked defaults for various lightmass solver and export settings ; Artist-oriented lightmass settings are in the editor UI ; Documentation for all of these is in UnrealLightmass/Public/SceneExport.h ; This ini is reloaded every time a lighting build begins, no need to restart [DevOptions.StaticLighting] bAllowMultiThreadedStaticLighting=True ViewSingleBounceNumber=-1 bUseBilinearFilterLightmaps=True bCompressLightmaps=True bUseConservativeTexelRasterization=True bAccountForTexelSize=True bUseMaxWeight=True MaxTriangleLightingSamples=8 MaxTriangleIrradiancePhotonCacheSamples=4 bAllow64bitProcess=True DefaultStaticMeshLightingRes=32 bAllowCropping=False bGarbageCollectAfterExport=True bRebuildDirtyGeometryForLighting=True bUseEmbree=true bVerifyEmbree=false [DevOptions.StaticLightingSceneConstants] StaticLightingLevelScale=1 VisibilityRayOffsetDistance=.1 VisibilityNormalOffsetDistance=3 VisibilityNormalOffsetSampleRadiusScale=.5 VisibilityTangentOffsetSampleRadiusScale=.8 SmallestTexelRadius=.1 ; Tweaked for a good tradeoff between 'Cache Indirect Photon Paths' time and Indirect photon emitting 'Sampling Lights' time LightGridSize=100 AutomaticImportanceVolumeExpandBy=500 MinimumImportanceVolumeExtentWithoutWarning=10000.0 [DevOptions.StaticLightingMaterial] bUseDebugMaterial=False ShowMaterialAttribute=None ; Material export sizes default to very small to keep exports fast EmissiveSampleSize=128 DiffuseSampleSize=128 SpecularSampleSize=128 TransmissionSampleSize=256 NormalSampleSize=256 ; Terrain materials default to much higher resolution since each material typically covers a large area in world space TerrainSampleScalar=4 DebugDiffuse=(R=0.500000,G=0.500000,B=0.500000) EnvironmentColor=(R=0.00000,G=0.00000,B=0.00000) [DevOptions.MeshAreaLights] bVisualizeMeshAreaLightPrimitives=False ; Only emissive texels above .01 will be used to create mesh area lights EmissiveIntensityThreshold=.01 MeshAreaLightGridSize=100 MeshAreaLightSimplifyNormalAngleThreshold=25 MeshAreaLightSimplifyCornerDistanceThreshold=.5 MeshAreaLightSimplifyMeshBoundingRadiusFractionThreshold=.1 MeshAreaLightGeneratedDynamicLightSurfaceOffset=30 [DevOptions.PrecomputedDynamicObjectLighting] bVisualizeVolumeLightSamples=False bVisualizeVolumeLightInterpolation=False NumHemisphereSamplesScale=2 SurfaceLightSampleSpacing=300 FirstSurfaceSampleLayerHeight=50 SurfaceSampleLayerHeightSpacing=250 NumSurfaceSampleLayers=2 DetailVolumeSampleSpacing=300 VolumeLightSampleSpacing=3000 ; Clamp the number of volume samples generated to ~15mb MaxVolumeSamples=250000 bUseMaxSurfaceSampleNum=True ; Approximately clamp the number of surface samples generated to ~30mb (only for Landscape currently) MaxSurfaceLightSamples=500000 [DevOptions.PrecomputedVisibility] bVisualizePrecomputedVisibility=False bCompressVisibilityData=True bPlaceCellsOnOpaqueOnly=True NumCellDistributionBuckets=800 CellRenderingBucketSize=5 NumCellRenderingBuckets=5 PlayAreaHeight=220 MeshBoundsScale=1.2 VisibilitySpreadingIterations=1 MinMeshSamples=14 MaxMeshSamples=40 NumCellSamples=24 NumImportanceSamples=40 [DevOptions.PrecomputedVisibilityModeratelyAggressive] MeshBoundsScale=1 VisibilitySpreadingIterations=1 [DevOptions.PrecomputedVisibilityMostAggressive] MeshBoundsScale=1 VisibilitySpreadingIterations=0 [DevOptions.VolumeDistanceField] VoxelSize=75 VolumeMaxDistance=900 NumVoxelDistanceSamples=800 ; Clamp the size of the volume distance field generated to ~15mb MaxVoxels=3992160 [DevOptions.StaticShadows] ; Using area shadows by default instead of filtering in texture space bUseZeroAreaLightmapSpaceFilteredLights=False NumShadowRays=8 NumPenumbraShadowRays=8 NumBounceShadowRays=1 bFilterShadowFactor=True ShadowFactorGradientTolerance=0.5 bAllowSignedDistanceFieldShadows=True MaxTransitionDistanceWorldSpace=50 ApproximateHighResTexelsPerMaxTransitionDistance=50 MinDistanceFieldUpsampleFactor=3 MinUnoccludedFraction=.005 StaticShadowDepthMapTransitionSampleDistanceX=100 StaticShadowDepthMapTransitionSampleDistanceY=100 StaticShadowDepthMapSuperSampleFactor=2 ; Clamp the number of shadow samples generated to ~8mb for huge levels StaticShadowDepthMapMaxSamples=4194304 [DevOptions.ImportanceTracing] bUseCosinePDF=False bUseStratifiedSampling=True NumHemisphereSamples=16 MaxHemisphereRayAngle=89 bUseAdaptiveSolver=true NumAdaptiveRefinementLevels=2 AdaptiveBrightnessThreshold=1 AdaptiveFirstBouncePhotonConeAngle=4 [DevOptions.PhotonMapping] bUsePhotonMapping=True bUseFinalGathering=True bUsePhotonDirectLightingInFinalGather=False bVisualizeCachedApproximateDirectLighting=False bUseIrradiancePhotons=True bCacheIrradiancePhotonsOnSurfaces=True bVisualizePhotonPaths=False bVisualizePhotonGathers=True bVisualizePhotonImportanceSamples=False bVisualizeIrradiancePhotonCalculation=False bEmitPhotonsOutsideImportanceVolume=False ConeFilterConstant=1 ; 400 gives a smooth enough result without requiring a very large search NumIrradianceCalculationPhotons=400 ; Allocating most final gather samples towards importance samples gives a good result as long as there are enough first bounce photons FinalGatherImportanceSampleFraction=.6 ; 10 degrees is a good tradeoff between capturing high frequency incident lighting at final gather points and covering the whole incident lighting domain with a limited number of importance directions FinalGatherImportanceSampleConeAngle=10 IndirectPhotonEmitDiskRadius=200 IndirectPhotonEmitConeAngle=30 MaxImportancePhotonSearchDistance=2000 MinImportancePhotonSearchDistance=20 ; Preview uses a very small number of importance directions NumImportanceSearchPhotons=10 OutsideImportanceVolumeDensityScale=.0005 DirectPhotonDensity=350 ; Same as DirectPhotonDensity, since currently direct photons are only used to create irradiance photons DirectIrradiancePhotonDensity=350 DirectPhotonSearchDistance=200 IndirectPhotonPathDensity=5 ; Need a very high indirect photon density since first bounce photons are used to guide the final gather IndirectPhotonDensity=600 IndirectIrradiancePhotonDensity=300 IndirectPhotonSearchDistance=200 PhotonSearchAngleThreshold=.5 IrradiancePhotonSearchConeAngle=10 CachedIrradiancePhotonDownsampleFactor=2 [DevOptions.IrradianceCache] bAllowIrradianceCaching=True bUseIrradianceGradients=False bShowGradientsOnly=False bVisualizeIrradianceSamples=True RecordRadiusScale=.8 InterpolationMaxAngle=20 PointBehindRecordMaxAngle=10 ; Increase distance and angle constraints in the shading pass, which filters the interpolated result without losing too much detail. DistanceSmoothFactor=4 AngleSmoothFactor=4 ; Sky occlusion has less noise than normal GI, don't blur away details SkyOcclusionSmoothnessReduction=.5 ; Enforce a minimum sample rate on surfaces with no nearby occluders MaxRecordRadius=1024 CacheTaskSize=64 InterpolateTaskSize=64 [DevOptions.StaticLightingMediumQuality] NumShadowRaysScale=2 NumPenumbraShadowRaysScale=4 ApproximateHighResTexelsPerMaxTransitionDistanceScale=3 MinDistanceFieldUpsampleFactor=3 NumHemisphereSamplesScale=2 NumImportanceSearchPhotonsScale=1 NumDirectPhotonsScale=2 DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=1 NumIndirectPhotonsScale=2 NumIndirectIrradiancePhotonsScale=2 RecordRadiusScaleScale=.75 InterpolationMaxAngleScale=1 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.5 AdaptiveFirstBouncePhotonConeAngleScale=1 [DevOptions.StaticLightingHighQuality] NumShadowRaysScale=4 NumPenumbraShadowRaysScale=8 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=4 NumImportanceSearchPhotonsScale=2 NumDirectPhotonsScale=2 DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 NumIndirectPhotonsScale=4 NumIndirectIrradiancePhotonsScale=2 RecordRadiusScaleScale=.75 InterpolationMaxAngleScale=.75 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2 [DevOptions.StaticLightingProductionQuality] NumShadowRaysScale=8 NumPenumbraShadowRaysScale=32 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=8 NumImportanceSearchPhotonsScale=3 NumDirectPhotonsScale=4 ; Decrease direct photon search distance so that we will have more accurate shadow transitions. This requires a higher density of direct photons. DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 ; Need a lot of indirect photons since we have increased the number of first bounce photons to use for final gathering with NumImportanceSearchPhotonsScale NumIndirectPhotonsScale=8 NumIndirectIrradiancePhotonsScale=2 ; Decreasing the record radius results in more records, which increases quality RecordRadiusScaleScale=.5625 InterpolationMaxAngleScale=.75 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2.5

Whoa! So many settings!

When Lighting Quality is set to Production: [DevOptions.StaticLightingProductionQuality] NumShadowRaysScale=8 NumPenumbraShadowRaysScale=32 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=8 NumImportanceSearchPhotonsScale=3 NumDirectPhotonsScale=4 ; Decrease direct photon search distance so that we will have more accurate shadow transitions. This requires a higher density of direct photons. DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 ; Need a lot of indirect photons since we have increased the number of first bounce photons to use for final gathering with NumImportanceSearchPhotonsScale NumIndirectPhotonsScale=8 NumIndirectIrradiancePhotonsScale=2 ; Decreasing the record radius results in more records, which increases quality RecordRadiusScaleScale=.5625 InterpolationMaxAngleScale=.75 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2.5

What do these each adjust? [DevOptions.StaticLightingProductionQuality] NumShadowRaysScale=8 NumPenumbraShadowRaysScale=32 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 Shadow Quality MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=8 Number of rays in final gathering NumImportanceSearchPhotonsScale=3 NumDirectPhotonsScale=4 DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 Number of photons and quality of photon mapping calculation NumIndirectPhotonsScale=8 NumIndirectIrradiancePhotonsScale=2 RecordRadiusScaleScale=.5625 InterpolationMaxAngleScale=.75 Irradiance Caching Quality IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2.5 Quality of Adaptive Sampling for Final Gathering

Scales important items collectively so that artists can adjust with just one setting

Possible to overwrite settings where necessary in DefaultLightmass.ini located in <ProjectName>¥Config

I will explain this later

Now, back to addressing artifacts

First, adjust Lighting Quality

Used Static Lighting Level Scale=0.1

Preview 2m16s

Medium 7m48s

High 13m58s

Production 30m22s

Quality is still insufficient

Need higher calculation accuracy for light

Adjust with Indirect Lighting Quality (Increase number of rays in final gathering)

Indirect Lighting Quality 1 Medium 7m48s

Indirect Lighting Quality 2 Medium 12m55s

Indirect Lighting Quality 5 Medium 29m46s

Indirect Lighting Quality 10 Medium 1h5m24s

Most artifacts disappear at 10

Static Lighting Level Scale=0.1 Indirect Lighting Quality=10 Production 4h10m24s

With Lighting Quality set to Production Level Static Lighting Level Scale×Indirect Lighting Quality =1.0 0.1 X 10 0.2 X 5 X 0.5 2 Artifacts can be reduced to an acceptable level when the above multiplication results in 1.0

Lightmass Settings Final Settings Static Lighting Level Scale= 0.1 Num Indirect Lighting Bounces=20 Indirect Lighting Quality = 10 Indirect Lighting Smoothness=1.0 Lighting Quality = Production

6. Lightmass Deep Dive

Let’s adjust Lightmass.ini

BaseLightmass.ini is in

C:¥Program Files¥Epic Games¥4.12¥Engine¥Config

; These are tweaked defaults for various lightmass solver and export settings ; Artist-oriented lightmass settings are in the editor UI ; Documentation for all of these is in UnrealLightmass/Public/SceneExport.h ; This ini is reloaded every time a lighting build begins, no need to restart [DevOptions.StaticLighting] bAllowMultiThreadedStaticLighting=True ViewSingleBounceNumber=-1 bUseBilinearFilterLightmaps=True bCompressLightmaps=True bUseConservativeTexelRasterization=True bAccountForTexelSize=True bUseMaxWeight=True MaxTriangleLightingSamples=8 MaxTriangleIrradiancePhotonCacheSamples=4 bAllow64bitProcess=True DefaultStaticMeshLightingRes=32 bAllowCropping=False bGarbageCollectAfterExport=True bRebuildDirtyGeometryForLighting=True bUseEmbree=true bVerifyEmbree=false [DevOptions.StaticLightingSceneConstants] StaticLightingLevelScale=1 VisibilityRayOffsetDistance=.1 VisibilityNormalOffsetDistance=3 VisibilityNormalOffsetSampleRadiusScale=.5 VisibilityTangentOffsetSampleRadiusScale=.8 SmallestTexelRadius=.1 ; Tweaked for a good tradeoff between 'Cache Indirect Photon Paths' time and Indirect photon emitting 'Sampling Lights' time LightGridSize=100 AutomaticImportanceVolumeExpandBy=500 MinimumImportanceVolumeExtentWithoutWarning=10000.0 [DevOptions.StaticLightingMaterial] bUseDebugMaterial=False ShowMaterialAttribute=None ; Material export sizes default to very small to keep exports fast EmissiveSampleSize=128 DiffuseSampleSize=128 SpecularSampleSize=128 TransmissionSampleSize=256 NormalSampleSize=256 ; Terrain materials default to much higher resolution since each material typically covers a large area in world space TerrainSampleScalar=4 DebugDiffuse=(R=0.500000,G=0.500000,B=0.500000) EnvironmentColor=(R=0.00000,G=0.00000,B=0.00000) [DevOptions.MeshAreaLights] bVisualizeMeshAreaLightPrimitives=False ; Only emissive texels above .01 will be used to create mesh area lights EmissiveIntensityThreshold=.01 MeshAreaLightGridSize=100 MeshAreaLightSimplifyNormalAngleThreshold=25 MeshAreaLightSimplifyCornerDistanceThreshold=.5 MeshAreaLightSimplifyMeshBoundingRadiusFractionThreshold=.1 MeshAreaLightGeneratedDynamicLightSurfaceOffset=30 [DevOptions.PrecomputedDynamicObjectLighting] bVisualizeVolumeLightSamples=False bVisualizeVolumeLightInterpolation=False NumHemisphereSamplesScale=2 SurfaceLightSampleSpacing=300 FirstSurfaceSampleLayerHeight=50 SurfaceSampleLayerHeightSpacing=250 NumSurfaceSampleLayers=2 DetailVolumeSampleSpacing=300 VolumeLightSampleSpacing=3000 ; Clamp the number of volume samples generated to ~15mb MaxVolumeSamples=250000 bUseMaxSurfaceSampleNum=True ; Approximately clamp the number of surface samples generated to ~30mb (only for Landscape currently) MaxSurfaceLightSamples=500000 [DevOptions.PrecomputedVisibility] bVisualizePrecomputedVisibility=False bCompressVisibilityData=True bPlaceCellsOnOpaqueOnly=True NumCellDistributionBuckets=800 CellRenderingBucketSize=5 NumCellRenderingBuckets=5 PlayAreaHeight=220 MeshBoundsScale=1.2 VisibilitySpreadingIterations=1 MinMeshSamples=14 MaxMeshSamples=40 NumCellSamples=24 NumImportanceSamples=40 [DevOptions.PrecomputedVisibilityModeratelyAggressive] MeshBoundsScale=1 VisibilitySpreadingIterations=1 [DevOptions.PrecomputedVisibilityMostAggressive] MeshBoundsScale=1 VisibilitySpreadingIterations=0 [DevOptions.VolumeDistanceField] VoxelSize=75 VolumeMaxDistance=900 NumVoxelDistanceSamples=800 ; Clamp the size of the volume distance field generated to ~15mb MaxVoxels=3992160 [DevOptions.StaticShadows] ; Using area shadows by default instead of filtering in texture space bUseZeroAreaLightmapSpaceFilteredLights=False NumShadowRays=8 NumPenumbraShadowRays=8 NumBounceShadowRays=1 bFilterShadowFactor=True ShadowFactorGradientTolerance=0.5 bAllowSignedDistanceFieldShadows=True MaxTransitionDistanceWorldSpace=50 ApproximateHighResTexelsPerMaxTransitionDistance=50 MinDistanceFieldUpsampleFactor=3 MinUnoccludedFraction=.005 StaticShadowDepthMapTransitionSampleDistanceX=100 StaticShadowDepthMapTransitionSampleDistanceY=100 StaticShadowDepthMapSuperSampleFactor=2 ; Clamp the number of shadow samples generated to ~8mb for huge levels StaticShadowDepthMapMaxSamples=4194304 [DevOptions.ImportanceTracing] bUseCosinePDF=False bUseStratifiedSampling=True NumHemisphereSamples=16 MaxHemisphereRayAngle=89 bUseAdaptiveSolver=true NumAdaptiveRefinementLevels=2 AdaptiveBrightnessThreshold=1 AdaptiveFirstBouncePhotonConeAngle=4 [DevOptions.PhotonMapping] bUsePhotonMapping=True bUseFinalGathering=True bUsePhotonDirectLightingInFinalGather=False bVisualizeCachedApproximateDirectLighting=False bUseIrradiancePhotons=True bCacheIrradiancePhotonsOnSurfaces=True bVisualizePhotonPaths=False bVisualizePhotonGathers=True bVisualizePhotonImportanceSamples=False bVisualizeIrradiancePhotonCalculation=False bEmitPhotonsOutsideImportanceVolume=False ConeFilterConstant=1 ; 400 gives a smooth enough result without requiring a very large search NumIrradianceCalculationPhotons=400 ; Allocating most final gather samples towards importance samples gives a good result as long as there are enough first bounce photons FinalGatherImportanceSampleFraction=.6 ; 10 degrees is a good tradeoff between capturing high frequency incident lighting at final gather points and covering the whole incident lighting domain with a limited number of importance directions FinalGatherImportanceSampleConeAngle=10 IndirectPhotonEmitDiskRadius=200 IndirectPhotonEmitConeAngle=30 MaxImportancePhotonSearchDistance=2000 MinImportancePhotonSearchDistance=20 ; Preview uses a very small number of importance directions NumImportanceSearchPhotons=10 OutsideImportanceVolumeDensityScale=.0005 DirectPhotonDensity=350 ; Same as DirectPhotonDensity, since currently direct photons are only used to create irradiance photons DirectIrradiancePhotonDensity=350 DirectPhotonSearchDistance=200 IndirectPhotonPathDensity=5 ; Need a very high indirect photon density since first bounce photons are used to guide the final gather IndirectPhotonDensity=600 IndirectIrradiancePhotonDensity=300 IndirectPhotonSearchDistance=200 PhotonSearchAngleThreshold=.5 IrradiancePhotonSearchConeAngle=10 CachedIrradiancePhotonDownsampleFactor=2 [DevOptions.IrradianceCache] bAllowIrradianceCaching=True bUseIrradianceGradients=False bShowGradientsOnly=False bVisualizeIrradianceSamples=True RecordRadiusScale=.8 InterpolationMaxAngle=20 PointBehindRecordMaxAngle=10 ; Increase distance and angle constraints in the shading pass, which filters the interpolated result without losing too much detail. DistanceSmoothFactor=4 AngleSmoothFactor=4 ; Sky occlusion has less noise than normal GI, don't blur away details SkyOcclusionSmoothnessReduction=.5 ; Enforce a minimum sample rate on surfaces with no nearby occluders MaxRecordRadius=1024 CacheTaskSize=64 InterpolateTaskSize=64 [DevOptions.StaticLightingMediumQuality] NumShadowRaysScale=2 NumPenumbraShadowRaysScale=4 ApproximateHighResTexelsPerMaxTransitionDistanceScale=3 MinDistanceFieldUpsampleFactor=3 NumHemisphereSamplesScale=2 NumImportanceSearchPhotonsScale=1 NumDirectPhotonsScale=2 DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=1 NumIndirectPhotonsScale=2 NumIndirectIrradiancePhotonsScale=2 RecordRadiusScaleScale=.75 InterpolationMaxAngleScale=1 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.5 AdaptiveFirstBouncePhotonConeAngleScale=1 [DevOptions.StaticLightingHighQuality] NumShadowRaysScale=4 NumPenumbraShadowRaysScale=8 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=4 NumImportanceSearchPhotonsScale=2 NumDirectPhotonsScale=2 DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 NumIndirectPhotonsScale=4 NumIndirectIrradiancePhotonsScale=2 RecordRadiusScaleScale=.75 InterpolationMaxAngleScale=.75 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2 [DevOptions.StaticLightingProductionQuality] NumShadowRaysScale=8 NumPenumbraShadowRaysScale=32 ApproximateHighResTexelsPerMaxTransitionDistanceScale=6 MinDistanceFieldUpsampleFactor=5 NumHemisphereSamplesScale=8 NumImportanceSearchPhotonsScale=3 NumDirectPhotonsScale=4 ; Decrease direct photon search distance so that we will have more accurate shadow transitions. This requires a higher density of direct photons. DirectPhotonSearchDistanceScale=.5 NumIndirectPhotonPathsScale=2 ; Need a lot of indirect photons since we have increased the number of first bounce photons to use for final gathering with NumImportanceSearchPhotonsScale NumIndirectPhotonsScale=8 NumIndirectIrradiancePhotonsScale=2 ; Decreasing the record radius results in more records, which increases quality RecordRadiusScaleScale=.5625 InterpolationMaxAngleScale=.75 IrradianceCacheSmoothFactor=.75 NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale=.25 AdaptiveFirstBouncePhotonConeAngleScale=2.5

Don’t worry!

Copy, paste, and edit values only where tuning is required, then put it in <ProjectName>¥Config as “DefaultLightmass.ini”

For example, when area shadow quality needs to be improved,

Increase shadow detail in DefaultLightmass.ini Default Values for Medium Setting

Allows tuning that is not available in Editor NumShadowRaysScale=16 NumPenumbraShadowRaysScale=64

Simply copy and paste from BaseLightmass.ini, and change the values Save as ”DefaultLightmass.ini” in <ProjectName>¥Config

Experimented with the various config file settings

Quality improves as number of rays increases but processing takes longer

Improving Final Gathering Increasing Indirect Lighting Quality ↓ Increases Number of Rays in Final gathering

Sufficient Rays Insufficient Rays Insufficient Rays Sufficient Rays Increasing rays across the entire area may be wasteful...

Improving Final Gathering Increasing Indirect Lighting Quality increases rays even where unnecessary ↓ Use adaptive sampling to increase rays only where necessary ↓ Increase level of adaptive sampling refinement or Decrease threshold of intensity when increasing the level

Increase level of adaptive sample refinement NumAdaptiveRefinementLevel

NumAdaptiveRefinementLevels = 0 Medium 1 m16s

NumAdaptiveRefinementLevels = 1 Medium 2 m15s

NumAdaptiveRefinementLevels = 2 Medium 4 m43s (Default Value when Lighting Quality is Preview)

NumAdaptiveRefinementLevels = 3 Medium 10 m59s (Default Value when Lighting Quality is Medium, High, or Production)

NumAdaptiveRefinementLevels = 4 Medium 34 m45s

Adjust threshold to increase level of adaptive sample refinement AdaptiveBrightnessThresholdScale

Static Lighting Level Scale = 0.2 Indirect Lighting Quality = 5 Medium Decided on the above settings

NumAdaptiveRefinementLevels = 3 AdaptiveBrightnessThresholdScale = 0.5 (Medium Default) 3 m 28 s

NumAdaptiveRefinementLevels=3 AdaptiveBrightnessThresholdScale = 0.25 3 m 33 s

NumAdaptiveRefinementLevels = 3 AdaptiveBrightnessThresholdScale = 0.05 4 m 13 s

NumAdaptiveRefinementLevels = 4 AdaptiveBrightnessThresholdScale = 0.5 12 m 41 s

NumAdaptiveRefinementLevels = 5 AdaptiveBrightnessThresholdScale = 0.25 48 m 03 s

Why is it so time consuming? Let’s compare when set at Static Lighting Level Scale = 0.2 and Indirect Lighting Quality = 10 Production

Static Lighting Level Scale=0.2 Indirect Lighting Quality=10 Production 28m22s

NumAdaptiveRefinementLevels = 5 AdaptiveBrightnessThresholdScale = 0.25 48 m 03 s

Because cost performance is low, increasing the number of rays of Indirect Lighting Quality is better.

Be careful when using a value of 11 or more for Indirect Lighting Quality

When Indirect Lighting Quality>11, NumAdaptiveRefinementLevel +1

Build time increases substantially.

Adjust the number of rays in Lightmass.ini Adjust “NumHemisphereSamplesScale” for each Lighting Quality level Or [DevOptions.ImportanceTracing] NumHemisphereSamples can scale the number of rays as well.

Lightmass.ini includes all settings required to apply custom tuning to your content.

Lets make Lightmass Epic https://forums.unrealengine.com/showthread.php?88952-Letsmake-Lightmass-EPIC-(and-understandable) Talented artists including Koola study Lightmass

Conclusion

Understanding differences in the behaviors of various lights is important. Especially Sky light! Emit Photons Emit No Photon • Directional Light • Point Light • Spot Light • Koola Bounce Card • Sky Light • Use Emissive For Static Lighting

What does each setting influence? Setting Influence on Influence on Build time Shadow Photon Mapping Lighting Quality Irradiance Caching Final Gathering Overall Quality Settings High

What each setting influences on? Setting Influence on Details of Lightmass Static Lighting Level Scale (Irradiance Caching recording radius) Influence on Build time Medium Brightness of Scene Num Indirect Lighting Bounces (Number of photon reflections) Low Decreases artifact noise Indirect Lighting Quality Indirect Lighting Smoothness (Number of rays for final gathering) Blurs indirect light component in Lightmap (Irradiance Caching Interpolation Ratio) High Low

Lightmass Quality (Detail) & Build Time = Lightmap Resolution (Increases Resolution) × Lighting Quality (Improves Overall Quality) × Indirect Lighting Quality (Decreases Artifacts) ÷ Static Lighting Level Scale (Improves Detail)

Any feedback or suggestions for better solutions is always welcome!

Thank you! http://www.frames-cg.com/ @torashami