Final gather is similar to global illumination, just following different rules and principles. It calculate light reflection and can create realism in some renders.
Final Gather works very similarly to the logic of Ambient Occlusion and Samples, the higher the values (In this instance the values being Accuracy, Point Density and Point Interpolation) the better the result. When trying to do things like test renders, either the test resolution may be decreased, or the values of the current render are altered. Instead of the image becoming very grainy, the image can take on an almost muddy appearance, or even sharp squares if the point density is low enough.
If your render ends up going very slow, sometimes it can be beneficial to use this menu to see if you can't reduce the render time, or see where problems occur one a map is created.
|Small Point Size|
|Large Point Size|
|Final Render with Final Gather|
I could definitely see how this render option would be useful, the smooth shading is something that can be achieved in other rendering options, however this renderer seems to be very smooth, almost looking like something you would see in Disney animations.
So Final Gather can also be linked to Mia Material x, in this instance, I was able to use a material created in the hypershade to give this model a glowing effect. Could be useful if I'm trying to create something Sci-Fi inspired.