Rectangular coordinate system in the solid angle calculation. FIG. 4.... | Download Scientific Diagram
![MathType on Twitter: "An object's #SolidAngle is the segment of a unit sphere that it covers when looking at the object from the centre of the sphere. Although the Moon is much MathType on Twitter: "An object's #SolidAngle is the segment of a unit sphere that it covers when looking at the object from the centre of the sphere. Although the Moon is much](https://pbs.twimg.com/media/FM_EgImXMAAFios.jpg)
MathType on Twitter: "An object's #SolidAngle is the segment of a unit sphere that it covers when looking at the object from the centre of the sphere. Although the Moon is much
![optics - Calculate radiance of Lambertian emitters: Is the solid angle $\pi$ or $2 \pi$? - Physics Stack Exchange optics - Calculate radiance of Lambertian emitters: Is the solid angle $\pi$ or $2 \pi$? - Physics Stack Exchange](https://i.stack.imgur.com/rHjAv.jpg)