Small TAA Anti-flicker changes

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -746,6 +746,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Ignoring the disable SSR flags for recursive rendering.
 - Removed logic in the UI to disable parameters for contact shadows and fog volume components as it was going against the concept of the volume system.
 - Fixed the sub surface mask not being taken into account when computing ray traced sub surface scattering.
+- Slightly changed the TAA anti-flicker mechanism so that it is more aggressive on almost static images (only on High preset for now).
 
 ## [7.1.1] - 2019-09-05
 

com.unity.render-pipelines.high-definition/Runtime/PostProcessing/Shaders/TemporalAntiAliasing.shader

@@ -50,6 +50,7 @@ Shader "Hidden/HDRP/TemporalAA"
     #define CENTRAL_FILTERING NO_FILTERING
     #define HISTORY_CLIP DIRECT_CLIP
     #define ANTI_FLICKER 1
+    #define ANTI_FLICKER_MV_DEPENDENT 0
     #define VELOCITY_REJECTION (defined(ENABLE_MV_REJECTION) && 0)
     #define PERCEPTUAL_SPACE 1
     #define PERCEPTUAL_SPACE_ONLY_END 0 && (PERCEPTUAL_SPACE == 0)
@@ -63,6 +64,7 @@ Shader "Hidden/HDRP/TemporalAA"
     #define CENTRAL_FILTERING BLACKMAN_HARRIS
     #define HISTORY_CLIP DIRECT_CLIP
     #define ANTI_FLICKER 1
+    #define ANTI_FLICKER_MV_DEPENDENT 1
     #define VELOCITY_REJECTION defined(ENABLE_MV_REJECTION)
     #define PERCEPTUAL_SPACE 1
     #define PERCEPTUAL_SPACE_ONLY_END 0 && (PERCEPTUAL_SPACE == 0)
@@ -163,7 +165,13 @@ Shader "Hidden/HDRP/TemporalAA"
             // --------------- Get neighbourhood information and clamp history --------------- 
             float colorLuma = GetLuma(filteredColor);
             float historyLuma = GetLuma(history);
-            GetNeighbourhoodCorners(samples, historyLuma, colorLuma, float2(_AntiFlickerIntensity, _ContrastForMaxAntiFlicker));
+
+#if ANTI_FLICKER_MV_DEPENDENT || VELOCITY_REJECTION
+            float motionVectorLength = length(motionVector);
+#else
+            float motionVectorLength = 0.0f;
+#endif
+            GetNeighbourhoodCorners(samples, historyLuma, colorLuma, float2(_AntiFlickerIntensity, _ContrastForMaxAntiFlicker), motionVectorLength);
 
             history = GetClippedHistory(filteredColor, history, samples.minNeighbour, samples.maxNeighbour);
             filteredColor = SharpenColor(samples, filteredColor, sharpenStrength);
@@ -189,7 +197,7 @@ Shader "Hidden/HDRP/TemporalAA"
             // --------------- Blend to final value and output ---------------
 
 #if VELOCITY_REJECTION
-            float lengthMV = length(motionVector) * 10;
+            float lengthMV = motionVectorLength * 10;
             blendFactor = ModifyBlendWithMotionVectorRejection(_InputVelocityMagnitudeHistory, lengthMV, prevUV, blendFactor, _SpeedRejectionIntensity);
 #endif
 

com.unity.render-pipelines.high-definition/Runtime/PostProcessing/Shaders/TemporalAntialiasing.hlsl

@@ -526,7 +526,7 @@ void MinMaxNeighbourhood(inout NeighbourhoodSamples samples)
     samples.avgNeighbour *= rcp(NEIGHBOUR_COUNT);
 }
 
-void VarianceNeighbourhood(inout NeighbourhoodSamples samples, float historyLuma, float colorLuma, float2 antiFlickerParams)
+void VarianceNeighbourhood(inout NeighbourhoodSamples samples, float historyLuma, float colorLuma, float2 antiFlickerParams, float motionVectorLen)
 {
     CTYPE moment1 = 0;
     CTYPE moment2 = 0;
@@ -552,20 +552,29 @@ void VarianceNeighbourhood(inout NeighbourhoodSamples samples, float historyLuma
     // and high temporal contrast, we let the history to be closer to be unclipped. To achieve, the min/max bounds
     // are extended artificially more.
 #if ANTI_FLICKER
-    stDevMultiplier = 1.4;
+    stDevMultiplier = 1.5;
     float temporalContrast = saturate(abs(colorLuma - historyLuma) / Max3(0.2, colorLuma, historyLuma));
-    stDevMultiplier += lerp(0.0, antiFlickerParams.x, smoothstep(0.05, antiFlickerParams.y, temporalContrast));
+#if ANTI_FLICKER_MV_DEPENDENT
+    const float screenDiag = length(_ScreenSize.xy);
+    const float maxFactorScale = 2.25f; // when stationary
+    const float minFactorScale = 0.8f; // when moving more than slightly
+    float localizedAntiFlicker = lerp(antiFlickerParams.x * minFactorScale, antiFlickerParams.x * maxFactorScale, saturate(1.0f - 2.0f * (motionVectorLen * screenDiag)));
+#else
+    float localizedAntiFlicker = antiFlickerParams.x;
+#endif
+    stDevMultiplier += lerp(0.0, localizedAntiFlicker, smoothstep(0.05, antiFlickerParams.y, temporalContrast));
+
 #endif
     samples.minNeighbour = moment1 - stdDev * stDevMultiplier;
     samples.maxNeighbour = moment1 + stdDev * stDevMultiplier;
 }
 
-void GetNeighbourhoodCorners(inout NeighbourhoodSamples samples, float historyLuma, float colorLuma, float2 antiFlickerParams)
+void GetNeighbourhoodCorners(inout NeighbourhoodSamples samples, float historyLuma, float colorLuma, float2 antiFlickerParams, float motionVecLen)
 {
 #if NEIGHBOUROOD_CORNER_METHOD == MINMAX
     MinMaxNeighbourhood(samples);
 #else
-    VarianceNeighbourhood(samples, historyLuma, colorLuma, antiFlickerParams);
+    VarianceNeighbourhood(samples, historyLuma, colorLuma, antiFlickerParams, motionVecLen);
 #endif
 }