RenderingEngines

Rendering engines are software systems that convert a description of a 3D scene into a 2D image. They form the core of computer graphics pipelines in applications ranging from video games and virtual reality to film production and architectural visualization. Rendering engines can operate in real time, producing images at interactive frame rates, or offline, generating highly accurate images with extensive sampling.

Scenes are defined by geometry, materials, lights, and cameras. The renderer evaluates visibility, shades surfaces, and outputs pixel values. Rendering methods differ: rasterization processes triangles and shading primarily for speed, while ray tracing follows rays from the camera to determine intersections and lighting; path tracing extends this to approximate global illumination by sampling many light paths per pixel. Modern engines blend techniques, use denoising, and support physically based rendering to simulate real-world light behavior.

Most engines implement a rendering pipeline with stages such as geometry processing, shading, rasterization or ray tracing, and image composition. Real-time engines rely on GPU acceleration, attention to memory bandwidth, and acceleration structures like BVHs or grids. Offline renderers optimize for image fidelity, using advanced sampling, global illumination, and physically based materials. Shaders, materials, and lighting are controlled by domain-specific languages or node-based editors.

Rendering engines emerged from early scanline and rasterization techniques to advanced physically based renderers. Notable examples include RenderMan, Arnold, V-Ray, Octane, Cycles, Eevee, and the real-time renderers integrated in Unreal Engine and Unity.