Säteenjäljitystä

Säteenjäljitystä, known in English as ray tracing, is a computer graphics rendering technique used to produce highly realistic images. It works by simulating the physical behavior of light. Instead of approximating how light interacts with surfaces, ray tracing traces the path of individual light rays from the camera's viewpoint back into the scene.

When a ray intersects an object, the algorithm determines the color of that point on the surface. This involves calculating how the light reflects, refracts, or is absorbed. For reflections, a new ray is spawned from the intersection point in the direction of the reflection. Similarly, for refraction through transparent objects like glass or water, a ray is bent according to Snell's Law. Shadows are created by casting rays from the intersection point towards light sources; if a ray is blocked by another object, the point is in shadow.

The complexity of ray tracing lies in the sheer number of rays that need to be traced to create a coherent image. Each pixel on the screen typically requires tracing multiple rays to account for various light interactions and to reduce noise. This computational intensity makes real-time ray tracing challenging, though advancements in hardware, particularly graphics processing units (GPUs), have made it increasingly feasible for interactive applications like video games. Despite its computational demands, ray tracing is highly effective at rendering realistic effects such as soft shadows, accurate reflections, and subtle ambient occlusion, which are difficult to achieve with simpler rendering methods like rasterization.