• - position in space
• - outgoing direction of light (towards the eye)
• - incoming direction of light (towards the light)
• - surface normal vector at
• - hemisphere of unit directions oriented around
• - light leaving in direction
• - light emitted at in direction
• - proportion of light reflected from to (BRDF)
• - light incoming at from direction
• - Cosine term (N dot L)

• - Outgoing light from the given point
• - Emitted light from the given point
• - The hemisphere of directions oriented around the normal
• - Ratio of incoming and outgoing light (BRDF)
• - Light incoming to the given point
• - Cosine term (N dot L) - more on this later

Can we calculate the rendering equation analytically? No, because the incoming light from a given direction depends on the scene we are rendering! There exists no general solution to the rendering equation, so what can we do - we use Monte carlo methods!

#light-transport #global-illumination