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Delta is a generic, 'energy conserving' material. 'Energy conserving' means the amount of reflection and the amount of diffuse shading is always equal to the amount of light illuminating the surface. LightWave's old surface could specify 100% diffuse and 100% reflection levels, resulting in overbright reflections. Delta does not have this problem.

Specularity: The amount of reflectivity of the surface. This applies to both reflections and specular highlights.

Roughness: The roughness of the surface affects both the amount of blurriness of blurred reflections, and the width of specular highlights.