I would just like to point out, Ray tracing is not some holy grail of perfection, far from it. Indeed buck for buck, rasterisation provides the same or higher image quality for a much lower cost.
Now obviously there are instances where raytracing helps, reflections and refractions can be generated on a per-pixel bases rather than rendering the reflection/refraction as a separate image and stretching/squishing said images in order to produce a similar effect. But saying this, if you render these separate images at a high enough quality you will get the same detail as a raytraced image, and still at a much lower cost than raytracing.
Ray tracing also does not help with shadows; For example, soft shadows. To raytrace a soft shadow you have to send out at least 16 rays per shadow calculation, for each light and even then your gonna suffer from nasty artefacts. Compared to the raster solution which involves rendering the zbuffer of any given light source and merely doing some blurring. same quality, much reduced cost.
I just wish that instead of investing so much time and effort into raytracing solutions people would instead apply the hardware that's generating these raytracing engines to a raster solution, if you took a conservative estimate of raster being 10x than raytracing for any given operation, then we are talking a huge leap forward in quality, a much larger leap than ray-traced reflections/refractions would give us.