I've been looking at improving my understanding of solid angles, and the Wikipedia page left me confused. They describe solid angles as being the projected area of an object as perceived by an observer at some distance, which kind of makes sense. However, when I look at solid angles in the context of computer graphics radiometry, they are being treated as differential oriented angles. as an azimuth/elevation pair with respect to the surface normal! Is it really the same thing?

I've been looking at improving my understanding of solid angles, and the Wikipedia page left me confused. They describe solid angles as being the projected area of an object as perceived by an observer at some distance, which kind of makes sense. However, when I look at solid angles in the context of computer graphics radiometry, they are being treated as differential oriented angles. with an azimuth/elevation pair with respect to the surface normal! Is it really the same thing?