Ray tracing principles and advantages and disadvantages

Ray tracing is a method of truly displaying objects, which was proposed by Appe in 1968. The ray tracing method tracks in the opposite direction of the light reaching the viewpoint, passes through each pixel on the screen, finds the surface point P0 of the object that intersects with the line of sight, and continues tracking to find all the light sources that affect the intensity of the P0 point, thereby calculating The precise light intensity at P0 is often used to represent the mirror effect in material editing.

Ray tracing or track tracing is one of the core algorithms of computer graphics. In the algorithm, light is ejected from the light source, and when they pass through the surface of the object, they apply a variety of transformations that comply with the laws of physical optics. Eventually, light enters the virtual camera negative and the picture is generated.

advantage

The prevalence of ray tracing comes from the fact that it is more realistic to simulate light than other rendering methods such as scan line rendering or ray casting. Some effects such as reflection and shadow are difficult to achieve for other algorithms, but they are ray tracing algorithms. A natural result. Ray tracing is easy to implement and visually good, so it is usually the first area of ​​graphical programming.

Shortcomings

One of the biggest drawbacks of raytracing is performance. Scanline algorithms and other algorithms use data consistency to share computations between pixels, but ray tracing usually treats each light as a separate light, each time Calculations. However, this independent approach also has some other advantages, such as the ability to use more light to resist aliasing and improve image quality when needed. Although it correctly handles the phenomenon of mutual reflection and optical effects such as refraction, traditional ray tracing is not necessarily a true effect image, and true true-effect images can only be achieved when the rendering equation is very tight or fully implemented. Since the rendering equation describes the physical effect of each beam, implementing the rendering equation can give true real results, but this is usually not possible considering the required computing resources. Thus, all possible rendering models must be approximations of the rendering equation, and ray tracing is not necessarily the most viable method. Some methods, including photon mapping, are based on ray tracing to implement a part of the algorithm, but can get better results.