[Bf-blender-cvs] [902209eda52] blender-v2.82-release: Partial Fix T73043: Denoising Albedo not working well for Sheen

Lukas Stockner noreply at git.blender.org
Mon Jan 20 23:10:31 CET 2020


Commit: 902209eda52756f510c7ac21c9075e5ea465ad9e
Author: Lukas Stockner
Date:   Mon Jan 20 22:54:58 2020 +0100
Branches: blender-v2.82-release
https://developer.blender.org/rB902209eda52756f510c7ac21c9075e5ea465ad9e

Partial Fix T73043: Denoising Albedo not working well for Sheen

Similar to the Microfacet Closures, the Principled BSDF Sheen closure is
added at a high weight but typically results in fairly low values.
Therefore, the default weight is a bad indicator of importance.

The fix here is the same as it was back then for Microfacets:
Compute an average weight using the normal as the half-vector
and use it to scale down the sample weight and the albedo channel.

In addition to drastically improving denoising of materials with
sheen when using the new Denoising node, this also can reduce noise
on such materials considerably.

===================================================================

M	intern/cycles/kernel/closure/bsdf_principled_sheen.h
M	intern/cycles/kernel/kernel_passes.h
M	intern/cycles/kernel/osl/osl_closures.cpp
M	intern/cycles/kernel/svm/svm_closure.h

===================================================================

diff --git a/intern/cycles/kernel/closure/bsdf_principled_sheen.h b/intern/cycles/kernel/closure/bsdf_principled_sheen.h
index 1326d23668a..3707de29d73 100644
--- a/intern/cycles/kernel/closure/bsdf_principled_sheen.h
+++ b/intern/cycles/kernel/closure/bsdf_principled_sheen.h
@@ -26,13 +26,26 @@ CCL_NAMESPACE_BEGIN
 
 typedef ccl_addr_space struct PrincipledSheenBsdf {
   SHADER_CLOSURE_BASE;
+  float avg_value;
 } PrincipledSheenBsdf;
 
 static_assert(sizeof(ShaderClosure) >= sizeof(PrincipledSheenBsdf),
               "PrincipledSheenBsdf is too large!");
 
-ccl_device float3 calculate_principled_sheen_brdf(
-    const PrincipledSheenBsdf *bsdf, float3 N, float3 V, float3 L, float3 H, float *pdf)
+ccl_device_inline float calculate_avg_principled_sheen_brdf(float3 N, float3 I)
+{
+  /* To compute the average, we set the half-vector to the normal, resulting in
+   * NdotI = NdotL = NdotV = LdotH */
+  float NdotI = dot(N, I);
+  if (NdotI < 0.0f) {
+    return 0.0f;
+  }
+
+  return schlick_fresnel(NdotI) * NdotI;
+}
+
+ccl_device float3
+calculate_principled_sheen_brdf(float3 N, float3 V, float3 L, float3 H, float *pdf)
 {
   float NdotL = dot(N, L);
   float NdotV = dot(N, V);
@@ -49,9 +62,11 @@ ccl_device float3 calculate_principled_sheen_brdf(
   return make_float3(value, value, value);
 }
 
-ccl_device int bsdf_principled_sheen_setup(PrincipledSheenBsdf *bsdf)
+ccl_device int bsdf_principled_sheen_setup(const ShaderData *sd, PrincipledSheenBsdf *bsdf)
 {
   bsdf->type = CLOSURE_BSDF_PRINCIPLED_SHEEN_ID;
+  bsdf->avg_value = calculate_avg_principled_sheen_brdf(bsdf->N, sd->I);
+  bsdf->sample_weight *= bsdf->avg_value;
   return SD_BSDF | SD_BSDF_HAS_EVAL;
 }
 
@@ -69,7 +84,7 @@ ccl_device float3 bsdf_principled_sheen_eval_reflect(const ShaderClosure *sc,
 
   if (dot(N, omega_in) > 0.0f) {
     *pdf = fmaxf(dot(N, omega_in), 0.0f) * M_1_PI_F;
-    return calculate_principled_sheen_brdf(bsdf, N, V, L, H, pdf);
+    return calculate_principled_sheen_brdf(N, V, L, H, pdf);
   }
   else {
     *pdf = 0.0f;
@@ -107,7 +122,7 @@ ccl_device int bsdf_principled_sheen_sample(const ShaderClosure *sc,
   if (dot(Ng, *omega_in) > 0) {
     float3 H = normalize(I + *omega_in);
 
-    *eval = calculate_principled_sheen_brdf(bsdf, N, I, *omega_in, H, pdf);
+    *eval = calculate_principled_sheen_brdf(N, I, *omega_in, H, pdf);
 
 #ifdef __RAY_DIFFERENTIALS__
     // TODO: find a better approximation for the diffuse bounce
diff --git a/intern/cycles/kernel/kernel_passes.h b/intern/cycles/kernel/kernel_passes.h
index d372a4f3e61..7345e9ee5bb 100644
--- a/intern/cycles/kernel/kernel_passes.h
+++ b/intern/cycles/kernel/kernel_passes.h
@@ -80,6 +80,10 @@ ccl_device_inline void kernel_update_denoising_features(KernelGlobals *kg,
         MicrofacetBsdf *bsdf = (MicrofacetBsdf *)sc;
         closure_albedo *= bsdf->extra->fresnel_color;
       }
+      else if (sc->type == CLOSURE_BSDF_PRINCIPLED_SHEEN_ID) {
+        PrincipledSheenBsdf *bsdf = (PrincipledSheenBsdf *)sc;
+        closure_albedo *= bsdf->avg_value;
+      }
 
       albedo += closure_albedo;
       sum_nonspecular_weight += sc->sample_weight;
diff --git a/intern/cycles/kernel/osl/osl_closures.cpp b/intern/cycles/kernel/osl/osl_closures.cpp
index 27205df3732..463a65f21a0 100644
--- a/intern/cycles/kernel/osl/osl_closures.cpp
+++ b/intern/cycles/kernel/osl/osl_closures.cpp
@@ -197,15 +197,32 @@ CLOSURE_FLOAT3_PARAM(DiffuseClosure, params.N),
     CLOSURE_FLOAT_PARAM(PrincipledDiffuseClosure, params.roughness),
     BSDF_CLOSURE_CLASS_END(PrincipledDiffuse, principled_diffuse)
 
-        BSDF_CLOSURE_CLASS_BEGIN(PrincipledSheen,
-                                 principled_sheen,
-                                 PrincipledSheenBsdf,
-                                 LABEL_DIFFUSE)
-            CLOSURE_FLOAT3_PARAM(PrincipledSheenClosure, params.N),
-    BSDF_CLOSURE_CLASS_END(PrincipledSheen, principled_sheen)
+        class PrincipledSheenClosure : public CBSDFClosure {
+ public:
+  PrincipledSheenBsdf params;
+
+  void setup(ShaderData *sd, int path_flag, float3 weight)
+  {
+    if (!skip(sd, path_flag, LABEL_DIFFUSE)) {
+      PrincipledSheenBsdf *bsdf = (PrincipledSheenBsdf *)bsdf_alloc_osl(
+          sd, sizeof(PrincipledSheenBsdf), weight, &params);
+      sd->flag |= (bsdf) ? bsdf_principled_sheen_setup(sd, bsdf) : 0;
+    }
+  }
+};
 
-    /* PRINCIPLED HAIR BSDF */
-    class PrincipledHairClosure : public CBSDFClosure {
+static ClosureParam *bsdf_principled_sheen_params()
+{
+  static ClosureParam params[] = {CLOSURE_FLOAT3_PARAM(PrincipledSheenClosure, params.N),
+                                  CLOSURE_STRING_KEYPARAM(PrincipledSheenClosure, label, "label"),
+                                  CLOSURE_FINISH_PARAM(PrincipledSheenClosure)};
+  return params;
+}
+
+CCLOSURE_PREPARE_STATIC(closure_bsdf_principled_sheen_prepare, PrincipledSheenClosure)
+
+/* PRINCIPLED HAIR BSDF */
+class PrincipledHairClosure : public CBSDFClosure {
  public:
   PrincipledHairBSDF params;
 
@@ -425,8 +442,11 @@ void OSLShader::register_closures(OSLShadingSystem *ss_)
                    id++,
                    bsdf_principled_diffuse_params(),
                    bsdf_principled_diffuse_prepare);
-  register_closure(
-      ss, "principled_sheen", id++, bsdf_principled_sheen_params(), bsdf_principled_sheen_prepare);
+  register_closure(ss,
+                   "principled_sheen",
+                   id++,
+                   bsdf_principled_sheen_params(),
+                   closure_bsdf_principled_sheen_prepare);
   register_closure(ss,
                    "principled_clearcoat",
                    id++,
diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index 1511fc65835..bf2d3f4fbff 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -290,7 +290,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg,
           bsdf->N = N;
 
           /* setup bsdf */
-          sd->flag |= bsdf_principled_sheen_setup(bsdf);
+          sd->flag |= bsdf_principled_sheen_setup(sd, bsdf);
         }
       }



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