Solid angle to the unit sphere with center P, which can be calculated as the surface integral: where formula_5 is the unit vector corresponding to formula_6, the position vector of an infinitesimal area of surface with respect to point P, and where formula_7 represents the unit normal vector to . Even if the projection on the unit sphere to the surface S is not isomorphic, the multiple folds are correctly considered according to the surface orientation described by the sign of the scalar product formula_8. Thus one can approximate the solid angle subtended by a small facet having flat surface area ,
Solid surface Solid surface Solid surface is a man-made material usually composed of a combination of alumina trihydrate (ATH), acrylic, epoxy or polyester resins and pigments. It is most frequently used for seamless countertop installations. Solid surface was first introduced by DuPont in 1967 under the name of Corian. Since the expiration of their patent, other manufacturers have also introduced their brands as well. Solid surface is a non-porous low-maintenance material used for surfaces such as countertops. It can mimic the appearance of granite, marble, stone, and other naturally occurring materials, and can be joined nearly invisibly by a trained craftsman. Typically