Path tracing

Path tracing is a rendering algorithm in <a href="/facts/Computer_graphics/lapBE8wv">computer graphics</a> that <a href="/facts/Simulation/Q4QJV1oI">simulates</a> how light interacts with <a href="/facts/Physical_object/WhqjK6xo">objects</a>, <a href="/facts/Voxel/xo077lPE">voxels</a>, and <a href="/facts/Volumetric_path_tracing/bh3v93Cj">participating media</a> to generate realistic (physically plausible) <a href="/facts/Raster_graphics/HkXNc8oI">images</a>.
This <a href="/facts/Ray_tracing_(graphics)/n6qpap2q">ray tracing</a> technique uses the <a href="/facts/Monte_Carlo_method/AkHjY7jc">Monte Carlo method</a> to accurately model <a href="/facts/Global_illumination/CbQX6CWM">global illumination</a>, simulate different surface characteristics, and capture a wide range of effects observable in a <a href="/facts/Camera/j4uqsfJQ">camera</a> system, such as optical properties of <a href="/facts/Lens/ejlH6n5c">lenses</a> (e.g., <a href="/facts/Depth_of_field/xWo3J8b0">depth of field</a> and <a href="/facts/Bokeh/BahN1Q2R">bokeh</a>) or the impact of <a href="/facts/Shutter_(photography)/83Y5rsB0">shutter</a> speed (e.g., <a href="/facts/Motion_blur/y7jR2shk">motion blur</a> and <a href="/facts/Exposure_value/A5QDoNGF">exposure</a>). By incorporating <a href="/facts/Physically_based_rendering/bRK5alKl">physically accurate materials</a> and <a href="/facts/Light_transport_theory/8sGhxVVp">light transport models</a>, it can produce <a href="/facts/Photorealism/HLAHwEvb">photorealistic</a> results but requires significant computational power. Performance is often constrained by <a href="/facts/Video_random-access_memory/WNdr2E26">VRAM</a>/<a href="/facts/Random-access_memory/DuD4bxh6">RAM</a> capacity and memory bandwidth, especially in complex scenes, necessitating <a href="/facts/Image_noise/zwhrU8lc">denoising</a> techniques for practical use. Additionally, the <a href="/facts/Garbage_in,_garbage_out/DsWyVwJN">Garbage In, Garbage Out (GIGO)</a> principle applies - inaccurate scene data, poor <a href="/facts/Geometric_modeling/SGyQGku9">geometry</a>, low-quality <a href="/facts/Physically_based_rendering/bRK5alKl">materials</a>, or incorrect rendering settings can negatively impact the final output, regardless of <a href="/facts/Rendering_(computer_graphics)/YYxfnmAq">rendering</a> precision.
Due to its accuracy, <a href="/facts/Unbiased_rendering/t6uL3u9T">unbiased</a> nature, and algorithmic simplicity, path tracing is commonly used to generate reference images when testing the quality of other rendering <a href="/facts/Algorithm/fnl5NmRt">algorithms</a>. Fundamentally, the algorithm works by <a href="/facts/Monte_Carlo_integration/YefNEuUg">integrating</a> the light arriving at a point on an object’s surface, where this <a href="/facts/Illuminance/6Dj4pKmu">illuminance</a> is then modified by a surface reflectance function (<a href="/facts/Bidirectional_reflectance_distribution_function/9LtejD2e">BRDF</a>) to determine how much light contributes to the final image, as seen by the camera. This integration procedure is repeated for every <a href="/facts/Pixel/UzwBvXBV">pixel</a> in the output image, ensuring detailed evaluation of each one. The number of samples per pixel (spp) determines the level of detail and quality of the final render, with more samples generally improving image clarity. Rendering performance is often measured in mega samples per second (Ms/sec), which reflects how many millions of samples can be processed per second, directly impacting rendering speed. Several variants of path tracing, such as bidirectional path tracing and <a href="/facts/Metropolis_light_transport/wRoPqI2f">Metropolis light transport</a>, have been developed to improve efficiency in various types of scenes, reducing noise and speeding up convergence.

Path tracing open-in-new

Path tracing