Solid angle

The quantity solid angle (denoted by the Greek letter Ω) is a measure of the field of view that a given object covers. The coresponding unit is steradian (sr). The solid angle (in sr) subtended by the area A (in m²) on the surface of the sphere with radius r (in m) is (see Figure):

Ω = A × r^-2

The solid angle subtended by the whole sphere measered from its interior is 4π sr.

Related units

• angle