title: Why do we use CPUs for ray tracing instead of GPUs?
body: <p>After doing some research on rasterisation and ray tracing. I have discovered that there is not much information on how CPUs work for ray-tracing available on the internet. I came across and article about Pixar and how they pre-rendered Cars 2 on the CPU. This took them 11.5 hours per frame. Would a GPU not have rendered this faster with the same image quality?
  <a href="http://gizmodo.com/5813587/12500-cpu-cores-were-required-to-render-cars-2" rel="noreferrer">http://gizmodo.com/5813587/12500-cpu-cores-were-required-to-render-cars-2</a>
  <a href="https://www.engadget.com/2014/10/18/disney-big-hero-6/" rel="noreferrer">https://www.engadget.com/2014/10/18/disney-big-hero-6/</a>
  <a href="http://www.firstshowing.net/2009/michael-bay-presents-transformers-2-facts-and-figures/" rel="noreferrer">http://www.firstshowing.net/2009/michael-bay-presents-transformers-2-facts-and-figures/</a>
  Cheers, 
  Sam</p>