Why does the metropolis light transport method provide such a clear image without much noise compared to path tracing in this image and a few slides back? Are there other methods that also achieve this more clear and realistic result?
Is path tracing generally inferior to the imaging results of the metropolis light transport method or are there types of images that the former would still be better/more efficient at? (e.g. smoke, heavy dust, etc.)
Is there a mathematical explanation of the decreased variance?