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Specularity is the visual appearance ofspecular reflections.
Incomputer graphics, it means the quantity used in three-dimensional (3D)rendering which represents the amount ofreflectivity a surface has. It is a key component in determining thebrightness ofspecular highlights, along withshininess to determine the size of thehighlights.
It is frequently used inreal-time computer graphics andray tracing, where the mirror-like specular reflection oflight from other surfaces is often ignored (due to the more intensive computations required to calculate it), and the specular reflection of light directly from point light sources is modeled as specular highlights.
Amaterials system may allow specularity to vary across a surface, controlled by additional layers oftexture maps.
Early shaders included a parameter called "Specularity". CG Artists, confused by this term discovered by experimentation that the manipulation of this parameter would cause a reflected highlight from a light source to appear and disappear and therefore misinterpreted "specularity" to mean "light highlights". In fact "Specular" is defined in optics asOptics. (of reflected light) directed, as from a smooth, polished surface (opposed todiffuse ). A specular surface is a highly smooth surface. When the surface is very smooth, the reflected highlight is easy to see. As the surface becomes rougher, the reflected highlights gets broader and dimmer. This is a more "diffused" reflection.[1][2]
In the context ofseismic migration, specularity is defined as the cosine of the angle made by thesurface normal vector and theangle bisector of the angle defined by the directions of the incident and diffracted rays.[3] For a purely specular seismic event the value of specularity should be equal to unity, as the angle between the surface normal vector and the angle bisector should be zero, according to Snell's Law. For a diffractive seismic event, the specularity can be sub-unitary. During the seismic migration, one can filter each seismic event according to the value of specularity, in order to enhance the contribution ofdiffractions in the seismic image. Alternatively, the events can be separated in different sub-images according to the value of specularity to produce aspecularity gather.[4]
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