Reflectance Distribution: This interactive tool demonstrates the differences between diffuse and specular reflections. Use your mouse or finger to click and drag the blue circle to adjust the angle of incidence of light on the surface. Then use the two sliders to adjust the reflectance and specularity properties of the surface to see the resulting reflection distribution.

This tool was developed to form part of the Performative Design Specularity definition page.

When people think of reflection, they usually think only of mirror-like or specular reflections from shiny surfaces. However, completely matte surfaces also reflect light and radiation, but do so diffusely where the light or radiation is distributed over a wide range of directions rather than just a single direction.

This interactive illustration represents a cross-section through the interface between air at the top and an opaque material at the bottom. When a light beam coming from the selected direction strikes the material, some portion of it will be reflected. The amount of the light energy reflected depends upon the Reflectance property of the material’s surface. The amounts of energy reflected in a specular or diffuse direction depends on it’s Specularity surface property.

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