Real time renderers focus on being real time as the most important constraint and therefore make lots of compromises and take a lot of shortcuts. Offline rende

Real time renderers focus on being real time as the most important constraint and therefore make lots of compromises and take a lot of shortcuts. Offline renderers try to simulate light transport as exactly as possible within a time budget. For example, one of the best algorithm to create high quality renders of scenes with very complicated light transport problems (something like this: [1]) uses ray-tracing monte-carlo integration techniques. Up until very recently, this was completely out of reach for a real time render. [1] https://blenderartists.org/uploads/default/original/4X/9/f/c/9fc01ed0e919d34be367328a28d8d9e58ead24a8.jpg https://blenderartists.org/uploads/default/original/4X/9/f/c...