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Glossary:Ray tracing (RT)

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Revision as of 23:45, 27 October 2023 by Aemony (talk | contribs) (additional work on the text)
Comparison of Metro Exodus (no ray tracing) and its Enhanced Edition (ray tracing).[1]
Comparison of Metro Exodus (no ray tracing) and its Enhanced Edition (ray tracing).[1]

Graphics and video

Resolutions

Video settings

Hardware

For a list of games, see games with ray tracing support.

Ray tracing (RT) is the generic name, umbrella terminology, and description used to describe various rendering methods or techniques and types in which light is realistically simulated to interact with the environment, as opposed to traditional light rendering methods where light data is hand-crafted based on the expected or current scene/environment. In relation to video games it refers to the simulation of light travelling from designated light sources in the environment (sun/sky, flashlight, lamps, fire, etc) to offer more realistic lighting enabling enhanced visuals and greater player immersion. However if not enough rays or bounces are used to fully establish the path of light, the consequences may be negative with visuals suffering from noise and flickering.

In 2018 the Nvidia GeForce RTX 20 (Turing) series of graphics cards were the first to integrate hardware accelerated real-time ray tracing in consumer level hardware, enabling its use in Battlefield V and a few other titles.[2] AMD followed this up in 2021 with their release of the Radeon RX 6000 series, their first generation of graphics cards with support for the feature.

As a consequence of calculating complex and advance light trajectories in real time at a playable framerate, the feature is quite demanding compared to traditional light rendering methods, necessitating the use of supportive features such as advanced ray tracing denoisers and high-fidelity upscaling technologies to improve visuals without increasing render resolution or ray or bounce count, reducing the overall system requirements of ray tracing. Despite these measures the requirements and performance impact remained high, causing slow adoption of the feature among consumers and developers; especially as early hardware generations with ray tracing support was unable to combine the feature with other often sought-after features at the time, such using a 4K resolution or achieving a high frame rate.

General information

Ray tracing (graphics)
Path tracing
Ray Tracing vs Path Tracing

Rendering methods

As of 2023 the predominant rendering methods used to implement ray tracing features are ray tracing (also known as the "normal" or "regular" ray tracing) as well as path tracing (also known as "full" or "real" ray tracing).

  • Ray tracing describes when the path of light is traced from a light source to any adjacent environment or object and back to said source.
  • Path tracing continues the traversal of the light around the adjacent area until the light reaches within the camera's view or a set number of bounces is reached.

Ray tracing is often separated and exposed as three different types depending on what they cover, with separate toggles in the game settings:

  • Ray Traced Shadows makes use of ray tracing to enable more realistic shadows of objects and characters based on surrounding light and character or object movement.
  • Ray Traced Reflections uses ray tracing to allow glass, water and other reflective surfaces to more accurately reflect the world around them from the perspective the player is viewing them in, even allowing objects or environments that might have otherwise been culled from being rendered to be visible to the player.
  • Ray Traced Global Illumination uses ray tracing for general environment light sources (such as a lamp in a room) to generate more natural and realistic looking lighting.

Games often only make use of one or two of the aformentioned types as the computational cost required makes it a risky feature for developers to use.

Path tracing is far less common due to the increased computational cost in comparison to regular ray tracing and covers all lighting scenarios described above leading to increased visual fidelity and immersion. As of October 2023 there have only been a few games released to date which uses path tracing, including Portal With RTX, Cyberpunk 2077, and Alan Wake 2.


References