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Atmospheric light scattering: Difference between revisions
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The altitude-dependent light reduction due to the clouds is the first instance of the '''lightfield''' technique, i.e. that the sunlight is represented as a series of functions r(x,y,z), g(x,y,z), b(x,y,z) in which the individual color channels are functions of vertex position in the scene. | The altitude-dependent light reduction due to the clouds is the first instance of the '''lightfield''' technique, i.e. that the sunlight is represented as a series of functions r(x,y,z), g(x,y,z), b(x,y,z) in which the individual color channels are functions of vertex position in the scene. | ||
=== Diffuse skylight === | |||
While the Sun is the main source of light during the day, Rayleigh scattering actually makes the whole sky a source of diffuse, sky-blue light coming predominantly from above. This diffuse skylight is especially important for the perception of glossy surfaces. Usually we identify these by their sharp specular reflections. However, using only the Sun as directional light source, a surface in shadow or facing away from the Sun has no specular reflection at all. Yet in reality, such surfaces still appear glossy, because they reflect the diffuse illumination coming from the sky. | |||
Implementing this effect in the rendering of models makes a subtle but important difference in how a glossy surface appears when facing away from the sun, as the two following screenshots illustrate: | |||
[[File:Diffuse skylight off.jpg|400px|Glossy surface rendered without skylight]] [[File:Diffuse skylight on.jpg|400px|Glossy surface rendered with skylight]] | |||
== Light scattering at dawn / dusk == | == Light scattering at dawn / dusk == | ||