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.

1 files changed, 1 insertions, 1 deletions

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);
         }
       }