Normal smoothing issue at high polycounts

High-poly models with smooth normals have some abnormalities compared to viewing in Blender. I’m viewing this using a material that shades based on normal direction threshold. Lower-poly models look exactly the same, but going up to a
128-segment 64-ring sphere (16k tris) shows some jagged bits.

The jagged lines aren’t along edges, they are in the middle of the faces and the angle change occurs when they hit the edges. This makes me think it’s a strange situation with the smoothing/interpolation of the normals.

I’ve turned high-precision normals on, but it didn’t seem to affect anything. I don’t think it’s an export issue because lower-poly models look exactly the same, it’s only when I get into abnormally high polycounts that it shows up.

I’ve got some more details and pictures in these forum threads:

“Use High Precision Tangent Basis”
Enable this per mesh basis form static mesh editor.

High Precision Static Mesh Vertex
Normal and Tangent Encoding

  • The single most important factor in achieving high quality reflections is
    how accurately the vertex normal and
    tangent can be represented. We added
    the option to encode normals and
    tangents as 16 bits per channel
    vectors. This allows developers make
    the trade off between higher quality
    and how much additional memory is used
    encoding vertex buffers. This option,
    Use High Precision Tangent Basis, can
    be found in the Build Settings section
    of the Static Mesh editor.

Thanks, this works perfectly. The “High Precision Normals” setting of “GBuffer Format” that I originally tried seems to be unnecessary for this.