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Ray tracing is a computer graphics term that describes the algorithm used for producing an image by tracing pixels and mimicking the path of light in an image plane. The technique is known for creating extremely realistic lighting effects. Although ray tracing is a commonly used process in Hollywood filmmaking, it is a new technique in video games and other virtual worlds. Previously, ray tracing has been used in animated film effects and now it is being translated to the visual effects in video games.
How it Works
Animators will begin with a very simple scene; it usually consists of a three-dimensional object and blank space. Then, a location in the image is picked and an imaginary camera is installed, which is known as the virtual camera. This camera is needed to create the desired image, so after it has been installed it must face a specific direction. Once the directional preference is achieved, an image plane made up of grids is placed and essentially illustrates what the camera sees in a plane perpendicular to the viewing direction.
As a collective unit, the camera, direction and plane allow the image to be rendered from different angles of the three-dimensional object. The renderer then sorts the colors of the presented pixels. To determine a color, a ray tracer must form a mathematical ray that originates at the camera, goes to the center of the pixel and then releases into the visual scene.
Accompanying this process is the ray tracer navigating the closest point of intersection for the other computer-generated objects and the ray itself. Once it meets at the intersection and the color determination is completed, the ray paints the picture in the chosen color. This process occurs for every single pixel of the three-dimensional simple image.
Ray tracing does not always have to produce big images or objects, sometimes it is even used for creating soft effects such as shadows and dim lighting.
Ray Tracing in Video Games
Ray tracing has entered the graphics of video games as a subtle but exceptional feature for gaming visuals. As the algorithm is known to mirror the human eye’s perception of light, as well as its effects and manipulations of space, it is developing a gaming landscape that is becoming increasingly realistic for players.
Ray tracing renders light and shadows in a way that is usually exclusive to TV and film. These scenes are technically generated once, but video games tend to follow a real-time and interactive nature. There is a systematic problem in which ray tracing has a high demand of server farms to pre-produce visuals. Therefore, television and film can reach this demand and sustain the power needed for server farms in a way that real-time visuals cannot.
In 2018, despite past incompatibility of video games and ray tracing a few technology companies such as Microsoft, Nvidia and Advanced Micro Devices declared that strategies to make ray tracing possible were in place for real-time video games. Microsoft is currently taking the biggest initiative as they have released the feature DirectX Raytracing, DXR, which enables real-time ray tracing for computer graphics.
Conclusion
Ray tracing was an idea first conceived in the late 1960s. Following its technological progression in the film industry, it is now beginning to reach more graphic mediums. The algorithm is credited for creating realistic lighting and shadows, as well as generating subtle effects to achieve the desired mood and ambience of particular scenes.
With the introduction of ray tracing to real-time graphics, photo-realism is progressing and reaching unimaginable technological heights. Ray tracing’s algorithm can expand visual realism further than simpler row-by-row, three-dimensional image developments such as scanline rendering.
Ray tracing’s slower speed and computational complexity makes it seem unapproachable and limited, but with multiple companies at the forefront of this popular technique, its optical effects of light scatter and reflection are becoming increasingly accessible in the field of computer graphics.
References
https://www.cs.utexas.edu/users/fussell/courses/cs384g-fall2011/lectures/lecture09-Ray_tracing.pdf
http://physics.bu.edu/~duffy/py106/Reflection.html
http://www.sci.utah.edu/~wald/PhD/wald_phd.pdf
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