Sphere mapping

<p>In <a href="/facts/Computer_graphics/lapBE8wv">computer graphics</a>, sphere mapping (or spherical environment mapping) is a type of <a href="/facts/Reflection_mapping/oPL8X8Br">reflection mapping</a> that approximates reflective surfaces by considering the environment to be an infinitely far-away spherical wall.  This environment is stored as a texture depicting what a mirrored sphere would look like if it were placed into the environment, using an <a href="/facts/Orthographic_projection/L3Cv9kYD">orthographic projection</a> (as opposed to one with <a href="/facts/Perspective_(graphical)/zkNx7Wpf">perspective</a>).  This texture contains reflective data for the entire environment, except for the spot directly behind the sphere.  (For one example of such an object, see Escher's drawing <a href="/facts/Hand_with_Reflecting_Sphere/gj4IT8h6">Hand with Reflecting Sphere</a>.)
</p><p>To use this data, the <a href="/facts/Surface_normal/jhtLIhcu">surface normal</a> of the object, view direction from the object to the camera, and/or reflected direction from the object to the environment is used to calculate a texture coordinate to look up in the aforementioned texture map.  The result appears like the environment is reflected in the surface of the object that is being rendered.
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Sphere mapping open-in-new

Sphere mapping