Solid angle of its faces is one-sixth of that, or sr. Solid angles can also be measured in square degrees (1 sr = () square degrees), in square minutes and square seconds, or in fractions of the sphere (1 sr = fractional area), also known as spat (1 sp = 4 sr). In spherical coordinates there is a formula for the differential, where is the colatitude (angle from the North pole) and is the longitude. The solid angle for an arbitrary oriented surface S subtended at a point P is equal to the solid angle of the projection of the surface S
Solid surface smaller, regional manufacturers produce for local markets. Although solid surface faces competition from natural stone and engineered stone/quartz surfacing, the material is popular in Asia, particularly in residential new construction. An emerging market for solid surface is in commercial and industrial settings, where its non-porous characteristics, combined with durability, renewability and formability make it the material of choice for many designers and architects. Also appealing, is the wide range of colors and textures, as well as the ability to custom-color the material for large projects. Hospitals, in particular, employ large amounts of solid surface for sinks, showers, nursing stations and