Шляхи Освітлення – Light Paths#

Reference – Довідка

Panel – Панель:: Render ‣ Light Paths

Ray Types#

Типи променів можна розділити на чотири категорії:

Камера – Camera: промінь надходить прямо з камери.
Відбиття – Reflection: промінь генерується відбиттям від поверхні.
Пропускання – Transmission: промінь генерується пропусканням крізь поверхню.
Тінь – Shadow: промінь використовується для (прозорих) тіней.

Промені відбиття та пропускання далі можуть мати такі властивості:

Розсіяння – Diffuse: промінь генерується розсіяними відбиттям або пропусканням (півпрозорість).
Глянець – Glossy: промінь генерується глянцевими бліковим відбиттям або пропусканням.
Сингулярно – Singular: промінь генерується ідеально різкими відбиттям або пропусканням.

Вузол Light Path може використовуватися для визначення типу променя, для якого буде обчислюватися відтінювання.

../../../_images/render_cycles_render-settings_light-paths_rays.svg

Дивись також

Устави видимості променя – ray visibility на рівні об’єкта.

Bounce Control#

The maximum number of light bounces can be controlled manually. While ideally this should be infinite, in practice a smaller number of bounces may be sufficient, or some light interactions may be intentionally left out for faster convergence. The number of diffuse reflection, glossy reflection and transmission bounces can also be controlled individually.

Light paths are terminated probabilistically when specifying a minimum number of light bounces lower than the maximum. In that case, paths longer than minimum will be randomly stopped when they are expected to contribute less light to the image. This will still converge to the same image, but renders faster while possibly being noisier.

Transparency – Прозорість#

The transparent BSDF shader is given special treatment. When a ray passes through it, light passes straight on, as if there was no geometry there. The ray type does not change when passing through a transparent BSDF.

Alpha pass output is also different for the transparent BSDF. Other transmission BSDFs are considered opaque, because they change the light direction. As such they cannot be used for alpha-over compositing, while this is possible with the transparent BSDF.

Зауважте, що хоча семантично промінь проходить крізь, ніби без натрапляння на геометрію, однак це впливає на продуктивність рендерингу, оскільки кожен крок прозорості вимагає виконання цього шейдера та простеження променя.

Settings – Устави#

Макс Відскоків – Max Bounces#

Сумарно – Total: Maximum number of light bounces. For best quality, this should be set to the maximum. However, in practice, it may be good to set it to lower values for faster rendering. A value of 0 bounces results in direct lighting only.

Розсіяння – Diffuse: Максимальна кількість відскоків розсіяння.

Глянець – Glossy: Максимальна кількість відскоків глянцю.

Transmission – Пропускання: Максимальна кількість відскоків пропускання.

Volume – Об’єм: Максимальна кількість відскоків розсіювання об’ємом.

Прозоро – Transparent

Максимальна кількість відскоків прозорості.

Note, the maximum number of transparent bounces is controlled separately from other bounces. It is also possible to use probabilistic termination of transparent bounces, which might help rendering many layers of transparency.

Clamping – Затискання#

Direct Light: This option limits the maximum intensity a sample from rays which have not yet bounced can contribute to a pixel. It reduces noise at the cost of accuracy. Setting this option to 0.0 disables clamping altogether. Lower have a greater affect (dimmer samples) on the resulting image than higher values.

Примітка

This option provides a way to limit Fireflies. However, note that as you clamp out such values, other bright lights/reflections will be dimmed as well.

Care must be taken when using this setting to find a balance between mitigating fireflies and losing intentionally bright parts. It is often useful to clamp indirect bounces separately, as they tend to cause more fireflies than direct bounces. See the Clamp Indirect setting.

Indirect Light: The same as Direct Light, but for rays which have bounced multiple times.

Caustics – Каустики#

A common source of noise is Caustics.

Дивись також

Дивіться про устави затиску для скорочення шуму тут – Reducing Noise.

Фільтр Глянцю – Filter Glossy

When using a value higher than 0.0, this will blur glossy reflections after blurry bounces, to reduce noise at the cost of accuracy. 1.0 is a good starting value to tweak.

Some light paths have a low probability of being found while contributing much light to the pixel. As a result these light paths will be found in some pixels and not in others, causing Fireflies. An example of such a difficult path might be a small light that is causing a small specular highlight on a sharp glossy material, which is observed through a rough glossy material. In fact in such a case there practically occurs a caustic.

With path tracing it is difficult to find the specular highlight, but if you increase the roughness on the material, the highlight gets bigger and softer, and so easier to find. Often this blurring will hardly be noticeable, because it is blurred by the material anyway, but there are also cases where this will lead to a loss of detail in lighting.

Caustics – Каустики

Reflective: While in principle path tracing supports rendering of caustics with a sufficient number of samples, in practice it may be inefficient to the point that there is just too much noise. This option can be unchecked, to disable reflective caustics.
Refractive: Подібно як Reflective Caustics, тільки щодо каустик заломлення.

Fast GI Approximation#

Reference – Довідка

Panel – Панель:: Render ‣ Light Paths ‣ Fast GI Approximation

Approximate diffuse indirect light with background tinted ambient occlusion. This provides fast alternative to full global illumination (GI), for interactive viewport rendering or final renders with reduced quality.

Method – Метод

Fast GI approximation method.

Replace – Заміна:: Replace global illumination with ambient occlusion after a specified number of bounces.
Add – Додання:: Add ambient occlusion to diffuse surfaces.

AO Factor: The strength of the ambient occlusion.

AO Distance

Distance from shading point to trace rays. A shorter distance emphasizes nearby features, while longer distances make it also take objects farther away into account.

This option can also be overridden per object in the Object Properties, which is useful when you have both small and large scale objects in the same scene.

Viewport Bounces: Replace global illumination with ambient occlusion after the specified number of bounces when rendering in the 3D Viewport. This can reduce noise in interior scenes with little visual difference.

Render Bounces: Number of bounces when rendering final renders.