I am observing strange blurring in refracted regions when per-vertex shading normals are present in PBRT-v4. When rendering the same scene with geometric normals only, refracted features appear sharp and stable. However, once per-vertex normals are included, PBRT-v4 produces noticeably blurred or washed-out regions along refractive paths.
This behavior is visible in both the Path and BDPT integrators with bilinear and triangle meshes. Interestingly, shading normals improve sharpness in some parts of the refracted image, but other areas—particularly near the center of the knot—become heavily blurred and lose detail entirely.
In contrast, PBRT-v3 produces uniformly sharper results when shading normals are provided, and does not exhibit the blurring seen in v4.
PBRT-v4
With vertex normals:
Without normals:
PBRT-v3
With vertex normals:
Without normals:
I am observing strange blurring in refracted regions when per-vertex shading normals are present in PBRT-v4. When rendering the same scene with geometric normals only, refracted features appear sharp and stable. However, once per-vertex normals are included, PBRT-v4 produces noticeably blurred or washed-out regions along refractive paths.
This behavior is visible in both the
PathandBDPTintegrators with bilinear and triangle meshes. Interestingly, shading normals improve sharpness in some parts of the refracted image, but other areas—particularly near the center of the knot—become heavily blurred and lose detail entirely.In contrast, PBRT-v3 produces uniformly sharper results when shading normals are provided, and does not exhibit the blurring seen in v4.
PBRT-v4
With vertex normals:
Without normals:
PBRT-v3
With vertex normals:
Without normals: