ORIGINAL GALVANIZED-STEEL PBR FINISH

One seamless 1 m tile, supplied as three 1024x1024 PNGs:
  BaseColor: sRGB colour; no baked lighting.
  ORM: linear data, R=constant 1, G=roughness about 0.38, B=metallic 1.
  Normal_OpenGL: linear tangent-space normal, OpenGL +Y, strength 1.
The red ORM channel is unoccluded constant data, not a geometry AO bake.
The GLB has no occlusionTexture; the stock importer uses G/B for roughness
and metallic. No height/displacement image is required or supplied.

Use repeat/wrap addressing and linear filtering. Each UV unit corresponds
to one metre of the source face projection. UV0 has intentional overlaps
and face-projection seams; it is not a unique atlas. There is no UV1 or
lightmap layout, or texel-density guarantee on every tiny bevel.

The original tile was generated from periodic 4D torus noise. Its subtle
normal uses periodic height differences at a 0.25 mm signal scale. It is
an original candidate finish, not an exact match to the private pilot's
unbaked 3D shader. No downloaded or competitor texture was used. The 8-bit
normal's red/green vary about 122-133 with blue 255; this is micrograin,
not deep damage, embossing or displacement.

Dark zinc fasteners use constant linear base colour (0.075,0.085,0.09),
metallic 1 and roughness 0.32. They need no image texture. The GLBs embed
the steel maps and constant fastener material; glTF materials are opaque
and two-sided. Keep the imported PBR connections when using the GLBs.

The tested Unreal Engine 5.8.2 stock Interchange import automatically used
sRGB BaseColor, non-sRGB metallic-roughness, and non-sRGB Normalmap
compression with Flip Green Channel enabled. NormalTexture remained active
at NormalScale=1 on UV0 with unit tiling. Do not also invert the PNG green
channel: that would apply the conversion twice. When creating a material
manually in another application, use its own tangent-normal convention.

Fully metallic faces reflect their lighting environment. Direct lights
alone can leave faces outside highlights dark. Provide your intended sky
or local reflection environment. A skylight's default black lower hemisphere
can darken faces reflecting below the horizon; for a uniform studio
environment, allow the selected cubemap across both hemispheres or choose
an intended lower-hemisphere colour. The accepted native reference used a
movable specified grey environment at intensity 1 with the black lower-
hemisphere clamp disabled, plus studio rect lights. This is reference
lighting, not baked asset lighting, an included engine environment, or
an exact Blender/Unreal image-parity promise. No engine files are shipped.
