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This is a fairly simplified explanation from Wikipedia.
Optical ray tracing describes a method for producing visual images constructed in 3D computer graphics environments, with more photorealism than either ray casting or scanline rendering techniques. It works by tracing a path from an imaginary eye through each pixel in a virtual screen, and calculating the color of the object visible through it.
Scenes in ray tracing are described mathematically by a programmer or by a visual artist (typically using intermediary tools). Scenes may also incorporate data from images and models captured by means such as digital photography.
Typically, each ray must be tested for intersection with some subset of all the objects in the scene. Once the nearest object has been identified, the algorithm will estimate the incoming light at the point of intersection, examine the material properties of the object, and combine this information to calculate the final color of the pixel. Certain illumination algorithms and reflective or translucent materials may require more rays to be re-cast into the scene.
Scenes in ray tracing are described mathematically by a programmer or by a visual artist (typically using intermediary tools). Scenes may also incorporate data from images and models captured by means such as digital photography.
Typically, each ray must be tested for intersection with some subset of all the objects in the scene. Once the nearest object has been identified, the algorithm will estimate the incoming light at the point of intersection, examine the material properties of the object, and combine this information to calculate the final color of the pixel. Certain illumination algorithms and reflective or translucent materials may require more rays to be re-cast into the scene.
It may at first seem counterintuitive or "backwards" to send rays away from the camera, rather than into it (as actual light does in reality), but doing so is many orders of magnitude more efficient. Since the overwhelming majority of light rays from a given light source do not make it directly into the viewer's eye, a "forward" simulation could potentially waste a tremendous amount of computation on light paths that are never recorded.
Therefore, the shortcut taken in raytracing is to presuppose that a given ray intersects the view frame. After either a maximum number of reflections or a ray traveling a certain distance without intersection, the ray ceases to travel and the pixel's value is updated.
Therefore, the shortcut taken in raytracing is to presuppose that a given ray intersects the view frame. After either a maximum number of reflections or a ray traveling a certain distance without intersection, the ray ceases to travel and the pixel's value is updated.
You can perhaps understand then that this would be a huge hit on any machine. With a few rare exceptions, ray traced scenes are not done in real-time. The processing power just isn't there. As an example, I used to do computer modelling and rendering back in high school (let's just say this was about 15+ years ago now). A simple scene with ray tracing could take hours if not entire days to render just a single frame. An exception to this is Quake Wars: Ray Traced. This was a research project by Intel that added a ray trace renderer to Enemy Territory: Quake Wars. The demo was created back in 2008. It ran at about 15-20fps at 720p on a system with four quad-core (2.93GHz) Xeon Tigerton CPUs. Another test machine used four six-core (2.66GHz) Xeon Dunnington CPUs to achieve 20-35fps.
What this means for you, someone who plays video games, is simple: Games will start to have far more photorealistic lighting, shadows, and materials. This will lead the way towards achieving Hollywood level visual effects all done in real time in a video game.
Microsoft is calling their new API "DirectX Raytracing" (DXR) and companies such as Nvidia and AMD have already voiced their support by way of updated hardware and software solutions. According to Anandtech, the initial support is a bit on the light side (no pun intended).
AMD says that they will have support for the API starting with a driver update. It's not yet sure if they have a hardware solution already in place on their cards or if a hardware solution will be coming in the next release.
Nvidia said that there will be hardware support starting with the Volta line. Specifically, Nvidia announced "Ray Tracing for GameWorks" (RTX), a new feature that will be a hardware solution on Volta cards and all of their cards moving forward. To be clear, RTX will also be a software solution for non-Volta cards but the advanced feature set will be tied to the new hardware.
Nvidia showed off RTX along with a real-time ray tracing demo thanks to some help by Remedy.