Editing Blender (software) (section)

=====Integrator=====
The integrator is the core [[rendering algorithm]] used for [[Rendering equation|lighting computations]]. Cycles currently supports a [[path tracing]] integrator with direct light sampling. It works well for a variety of lighting setups, but it is not as suitable for [[Caustic (optics)|caustics]] and certain other complex lighting situations. [[Ray tracing (graphics)|Rays are traced]] from the camera into the scene, bouncing around until they find a light source (a lamp, an object material emitting light, or the world background), or until they are simply terminated based on the number of maximum bounces determined in the light path settings for the renderer. To find lamps and surfaces emitting light, both indirect light sampling (letting the ray follow the surface [[Bidirectional scattering distribution function|bidirectional scattering distribution function, or BSDF]]) and direct light sampling (picking a light source and tracing a ray towards it) are used.<ref>{{cite web|title=Integrator — Blender Reference Manual|url=http://www.blender.org/manual/render/cycles/settings/integrator.html#integrator|website=www.blender.org|access-date=2015-10-18|archive-url=https://web.archive.org/web/20151009124836/http://www.blender.org/manual/render/cycles/settings/integrator.html#integrator|archive-date=2015-10-09|url-status=dead}}</ref>

The default path tracing integrator is a "pure" path tracer. This integrator works by sending several [[light rays]] that act as [[photon]]s from the camera out into the scene. These rays will eventually hit either: a light source, an object, or the world background. If these rays hit an object, they will bounce based on the angle of impact, and continue bouncing until a light source has been reached or until a maximum number of bounces, as determined by the user, which will cause it to terminate and result in a black, unlit pixel. Multiple rays are calculated and averaged out for each pixel, a process known as "sampling". This sampling number is set by the user and greatly affects the final image. Lower sampling often results in more noise and has the potential to create "fireflies" (which are uncharacteristically bright pixels), while higher sampling greatly reduces noise, but also increases render times.

The alternative is a branched path tracing integrator, which works mostly the same way. Branched path tracing splits the light rays at each intersection with an object according to different surface components,{{Clarify|reason=|date=December 2019}} and takes all lights into account for shading instead of just one. This added complexity makes computing each ray slower but reduces noise in the render, especially in scenes dominated by direct (one-bounce) lighting. This was removed in Blender 3.0 with the advent of Cycles X, as improvements to the pure path tracing integrator made the branched path tracing integrator redundant.<ref>{{cite web |title=Cycles X |url=https://code.blender.org/2021/04/cycles-x/#deprecation |website=Blender Developer Blog |date=23 April 2021 |access-date=2024-07-16 |archive-url=https://web.archive.org/web/20240706015139/https://code.blender.org/2021/04/cycles-x/#deprecation |archive-date=2024-07-06}}</ref>