From b01d16c2852ca4d858eeeea9a4c5bdcc25a0bb43 Mon Sep 17 00:00:00 2001
From: Alexander Gauggel <agauggel@uni-koblenz.de>
Date: Fri, 20 Aug 2021 14:18:24 +0200
Subject: [PATCH] [#106] Add motion blur mirrored background reconstruction
from Jimenez paper
---
.../resources/shaders/motionBlur.comp | 47 +++++++++++++++----
1 file changed, 38 insertions(+), 9 deletions(-)
diff --git a/projects/indirect_dispatch/resources/shaders/motionBlur.comp b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
index 459416b8..804c0ceb 100644
--- a/projects/indirect_dispatch/resources/shaders/motionBlur.comp
+++ b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
@@ -175,21 +175,50 @@ void main(){
// the sampleUV code expects an offset in range [-0.5, 0.5], so the dither is rescaled to a binary -0.25/0.25
float random = dither(coord) * 0.5 - 0.25;
- const int sampleCount = 15;
+ const int sampleCountHalf = 8;
- for(int i = 0; i < sampleCount; i++){
- vec2 sampleUV = mix(uvStart, uvEnd, (i + random + 1) / float(sampleCount + 1));
+ // two samples are processed at a time to allow for mirrored background reconstruction
+ for(int i = 0; i < sampleCountHalf; i++){
- SampleData samplePixel = loadSampleData(sampleUV);
- float weightSample = computeSampleWeigth(mainPixel, samplePixel);
+ vec2 sampleUV1 = mix(uv, uvEnd, (i + random + 1) / float(sampleCountHalf + 1));
+ vec2 sampleUV2 = mix(uv, uvStart, (i + random + 1) / float(sampleCountHalf + 1));
- weightSum += weightSample;
- color += samplePixel.color * weightSample;
+ SampleData sample1 = loadSampleData(sampleUV1);
+ SampleData sample2 = loadSampleData(sampleUV2);
+
+ float weight1 = computeSampleWeigth(mainPixel, sample1);
+ float weight2 = computeSampleWeigth(mainPixel, sample2);
+
+ bool mirroredBackgroundReconstruction = true;
+ if(mirroredBackgroundReconstruction){
+ // see Jimenez paper for details and comparison
+ // problem is that in the foreground the background is reconstructed, which is blurry
+ // in the background the background is obviously known, so it is sharper
+ // at the border between fore- and background this causes a discontinuity
+ // to fix this the weights are mirrored on this border, effectively reconstructing the background, even though it is known
+
+ // these bools check if sample1 is an affected background pixel (further away and slower moving than sample2)
+ bool inBackground = sample1.depthLinear > sample2.depthLinear;
+ bool blurredOver = sample1.velocityPixels < sample2.velocityPixels;
+
+ // this mirrors the weights depending on the results:
+ // if both conditions are true, then weight2 is mirrored to weight1
+ // if both conditions are false, then weight1 is mirrored to weight2, as sample2 is an affected background pixel
+ // if only one condition is true, then the weights are kept as is
+ weight1 = inBackground && blurredOver ? weight2 : weight1;
+ weight2 = inBackground || blurredOver ? weight2 : weight1;
+ }
+
+ weightSum += weight1;
+ weightSum += weight2;
+
+ color += sample1.color * weight1;
+ color += sample2.color * weight2;
}
// normalize color and weight
- weightSum /= sampleCount;
- color /= sampleCount;
+ weightSum /= sampleCountHalf * 2;
+ color /= sampleCountHalf * 2;
// the main color is considered the background
// the weight sum can be interpreted as the alpha of the combined samples, see Jimenez paper
--
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