erinimetusega ISQ tuletatud suurus, ruumi osa, mida piirab kooniline pind ja seda lõikav kate, ISQ derived quantity with special name, solid angle is a measure of the amount of the field of view from some particular point that a given object covers, solid angle made up of all the lines from a closed curve meeting at a vertex, is defined by the surface area of a sphere subtended by the lines and by the radius of that sphere, as shown below