Anisotropic reflection is reflection whose intensity and shape vary with the direction of a surface's microscopic structure, rather than looking the same when the surface is rotated in place. It produces stretched, directional highlights. Brushed metal, satin fabric, vinyl records, and human hair all show anisotropic reflection.
Most material models assume reflection is isotropic, meaning it looks the same when you rotate the surface in place. Anisotropic materials break this because their microscopic structure has a direction. Brushed metal has fine parallel grooves, fabric has woven threads, and hair has aligned strands.
Light reflecting off these aligned features spreads along the grooves rather than into a round highlight, which produces the stretched, streaked reflections seen on a brushed-steel watch back or a satin ribbon. Physically based material models capture this with a direction-aware bidirectional reflectance distribution function (BRDF) and a tangent direction that tells the renderer how the surface is oriented.
Anisotropy is what makes brushed metal read as brushed rather than flat gray, and satin read as satin rather than matte. It is also strongly view-dependent, which makes it difficult to capture and reconstruct accurately. Methods that assume a single fixed color per point, or that use low-frequency view-dependent encodings, tend to wash anisotropic highlights into a dull average.
For categories where finish is the selling point, such as watches, automotive trim, appliances, and apparel, losing anisotropy means losing the material's identity in the 3D version.
Anisotropic appearance is encoded by the asset and the representation chosen to capture it, not by the delivery layer. Miris conditions an asset once upstream and streams it adaptively to any device. It does not generate or refine anisotropic highlights. It delivers whatever the source representation contains. As capture and representation methods improve at preserving directional materials, those improvements reach viewers through the same Miris pipeline. The representation is the asset owner's choice. Miris owns the method of delivery.
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