As we collect more and more samples, we will ultimately converge on a likely answer. The more samples we collect or iterations we run, the more time it takes, but the better our guess will be. Therefore, our Iray renderer must guess what the value of a point is by sampling light from a set of different but finite angles. However, it is simply not possible to calculate the value of a point with real-world accuracy, because we would need to sample light coming in from an infinite number of directions.

For each point on the screen, it shoots out a ray from the camera to that point, then tries to determine its color/value.

Physically based renderers, such as Iray, tries to approximate the physics of reality. It may receive light from outside, there may be shadows cast from nearby objects, and there may be indirect lighting from nearby surfaces. Any single point can receive light from an infinite number of directions. We do not normally think about it, but real-world lighting is very complex.

Daz3d gpu render