Path Tracer
Updated: 25 Nov 2024
The highest quality offline renderer.
Path Tracer
Method #
This node is our highest quality Renderer, utilising pathtracing to render images with full global illumination, reflections, and refractions.
Suitable for rendering 3D content at the highest quality in stills or exporting to video.
Parameters
These properties control the general rendering features applied to the scene.
Parameter Details Max Refine Steps The max number of refine steps per frame. Early refinement steps will converge very quickly, but over time the scene will take longer to converge. The right number of refines varies greatly from scene to scene, so it’s wise to start with a lower number and bump it up incrementally until an acceptable balance of noise and render time is found.
Refining Mode Control how the image is refined.
- Full Refining : Every pixel is refined for the full number of refinement steps.
- Adaptive Refining : Every pixel is checked to see how much it has changed over a number of refinement steps, and if the differences are smaller than the threshold, then that pixel stops refining. Useful for optimising the refinement process, as it focuses refinement onto areas of high noise, so more refinement steps can be done without in a shorter period of time. On scenes which are already very noisey, the difference may be miniscule though - the right balance for your scene will vary, so experiment and hone in on the one you feel is most appropriate.
Antialiasing These options allow for different methods of reducing aliasing. For more about aliasing, see here our page on Antialiasing
- Off : No Anti-Aliasing is applied to the scene.
- On : Each ray is slightly diverted at a subpixel level, producing extremely accurate antialiasing which improves with further refinement steps.
AI Denoiser Uses an AI denoiser to denoie the final refined result. Each denoiser uses data from the GBuffer to denoise the scene, so reflective and refractive surfaces can often get denoised more aggressively than expected and often arent suitable or denoising.
- None : No denoiser is used.
- Intel OIDN : Enables the Intel OIDN denoiser.
- NVIDIA Optix : Enables the NVIDIA Optix denoiser.
Denoising Mode Control when a denoiser is applied to the scene, if denoising is enabled.
- Per Refine Step : The denoiser is applied every step of the refinement.
- After Refining : The denoiser is applied only after the entire frame has been fully refined.
Depth Of Field Control the depth of field rendered from the camera. Useful for drawing focus onto a specific area of the scene. The Blur Amount and Focus Distance can be controlled from the Camera node.
- Off : No depth of field will be applied.
- On : Offsets the starting position of every ray based on the cameras blurrines and focus parameters.
Motion Blur Control the motion blur rendered from the camera. Useful for adding smoother and more realistic motion to a scene. The Blur Amount can be controlled from the Camera node.
- Off : Control the motion blur rendered from the camera. Useful for adding smoother and more realistic motion to a scene. The Blur Amount can be controlled from the Camera node.
- On : Each ray is offset in time by a sub-frame amount, and motion vectors are generated for all the moving objects in the scene. The rays are traced and tested against these objects and their motion vectors to generate the motion blur. Gives fast and accurate results, but can generate strange smears if an object moves too erratically.
Brightness Clamp Sets a maximum output brightness value when sampling light in the scene. Useful for reducing ‘firefly’ noise in the scene, as further light samples are likely to average out faster, but can reduce the overall lighting accuracy in the scene.
Firefly Reduction Threshold Sets a max brightness value clamp after sampling, reducing noise in the resulting image and allowing the samples to converge more quickly. If exporting to HDR, this can clamp the brightness values significantly, so you may want to increase the threshold greatly for those cases.
Kill Caustic Paths Kills rays which the pathtracer identifies as caustic, and contribute noise which is difficult to refine. Allows the scene to refine quicker, but can be a little less accurate.
These properties control how lighting is calculated and affects the scene.
Parameter Details Diffuse Depth How many bounces of diffuse lighting are used. More bounces can increase the brightness in dark areas of the scene, but will have deminishing retuns at greater values.
Diffuse Bounce Multiplier Boost the brightness of diffuse bounces in the scene. Useful for artificially brightening unlit areas of a scene without adding extra diffuse bounces, but not accurate and if pushed too far can introduce artefacting and blow up the lighting model as surfaces reflect more light than they absorb.
Glossy Depth How many bounces of Specular lighting are used. More bounces may be necessary in scenes with lots of clean glass or mirrors, but in scenes with lots of rough surfaces lower values can be used to improve performance.
Refraction Depth How many refractive are used. Similar to glossy depth, more bounces may be necessary in scenes with lots of glass, but in scenes with no glass or lots of rough glass lower values can be used to improve performance.
Ambient Occlusion Simulates natural shadowing that occurs in corners and crevices of a scene, by darkening those areas. Useful for exaggerating detail in a scene.
- Off : No Ambient Occlusion is generated.
- Raytraced : The scene is raytraced by a global emissive light sourcec, so darkened areas will naturally receive less light.
AO Blend Mode Simulates natural shadowing that occurs in corners and crevices of a scene, by darkening those areas. Useful for exaggerating detail in a scene.
- Multiply : The Ambient Occlusions is multiplied against the scene after all the lighting passes have been generated.
- Replace : Replaces the current lighting with that of the Ambient Occlusion. Useful for getting a simple clay render of the scene.
- Add : Adds the Ambient Occlusion lighting on top of the lighting of the scene, brightening all areas except the areas the ambient occlusion is applied.
AO Blend Amount How much the of AO is applied to the scene, via the Blend Mode chosen. Doesn’t apply to Replace Blend Mode.
AO Distance Controls how wide the Ambient Occlusion radius is. Lower values tighten the ambient occlusion to smaller areas, larger value can end up darkening the whole object, and in some modes add visible noise.
AO Falloff Curve Controls how the weighting of ambient occlusion falls off over distance. Higher values will darken areas of ambient occlusion further, while lower values will lessen the ambient occlusion except in narrow crevices.
Radiance Cache Uses a radiance cache during refinement to speed up rendering. A sparse grid is generated across the entire scene, where the incoming light for all surfaces is cached. The lighting is then approximated over time, allowing subsequent frames to look up lighting from the cache instead of re-calculating it again. Can optimise scenes with lots of lights or lots of geometry, but generally not necessary for pathtraced scenes.
Scene Scale Controls the density of the radiance caches sparse grid. Higher values can make the improve the accuracy of the cache, but increase render time.
Lighting Far Plane Controls the distance away from the camera at which lighting will no longer be calculated. Lower values can increase performance in some scenes, but you’ll need to build the scene such that objects outside this range do not need lighting.
These properties control how light scattering is processed in the scene.
Parameter Details Scattering Enable raytraced scattering on lights in the scene. Only functions if lights have some scattering amount in use.
Scattering Intensity Multiplier on top of the global scattering density. Useful for adjusting the density globally without going to all the individual lights.
Smoke Density Applies a simple noise pattern over the scattering generated, giving an appearance of smokiness. Useful for generating a mysterious and foggy effect.
Smoke Scale Changes the scale of the smokiness parameters.
Smoke Speed How quickly the generated smoke is animated in the scene.
Inputs
These properties control the general rendering features applied to the scene.
| Parameter | Details |
|---|---|
| Max Refine Steps | The max number of refine steps per frame. Early refinement steps will converge very quickly, but over time the scene will take longer to converge. The right number of refines varies greatly from scene to scene, so it’s wise to start with a lower number and bump it up incrementally until an acceptable balance of noise and render time is found. |
| Refining Mode | Control how the image is refined.
|
| Antialiasing | These options allow for different methods of reducing aliasing. For more about aliasing, see here our page on Antialiasing
|
| AI Denoiser | Uses an AI denoiser to denoie the final refined result. Each denoiser uses data from the GBuffer to denoise the scene, so reflective and refractive surfaces can often get denoised more aggressively than expected and often arent suitable or denoising.
|
| Denoising Mode | Control when a denoiser is applied to the scene, if denoising is enabled.
|
| Depth Of Field | Control the depth of field rendered from the camera. Useful for drawing focus onto a specific area of the scene. The Blur Amount and Focus Distance can be controlled from the Camera node.
|
| Motion Blur | Control the motion blur rendered from the camera. Useful for adding smoother and more realistic motion to a scene. The Blur Amount can be controlled from the Camera node.
|
| Brightness Clamp | Sets a maximum output brightness value when sampling light in the scene. Useful for reducing ‘firefly’ noise in the scene, as further light samples are likely to average out faster, but can reduce the overall lighting accuracy in the scene. |
| Firefly Reduction Threshold | Sets a max brightness value clamp after sampling, reducing noise in the resulting image and allowing the samples to converge more quickly. If exporting to HDR, this can clamp the brightness values significantly, so you may want to increase the threshold greatly for those cases. |
| Kill Caustic Paths | Kills rays which the pathtracer identifies as caustic, and contribute noise which is difficult to refine. Allows the scene to refine quicker, but can be a little less accurate. |
These properties control how lighting is calculated and affects the scene.
| Parameter | Details |
|---|---|
| Diffuse Depth | How many bounces of diffuse lighting are used. More bounces can increase the brightness in dark areas of the scene, but will have deminishing retuns at greater values. |
| Diffuse Bounce Multiplier | Boost the brightness of diffuse bounces in the scene. Useful for artificially brightening unlit areas of a scene without adding extra diffuse bounces, but not accurate and if pushed too far can introduce artefacting and blow up the lighting model as surfaces reflect more light than they absorb. |
| Glossy Depth | How many bounces of Specular lighting are used. More bounces may be necessary in scenes with lots of clean glass or mirrors, but in scenes with lots of rough surfaces lower values can be used to improve performance. |
| Refraction Depth | How many refractive are used. Similar to glossy depth, more bounces may be necessary in scenes with lots of glass, but in scenes with no glass or lots of rough glass lower values can be used to improve performance. |
| Ambient Occlusion | Simulates natural shadowing that occurs in corners and crevices of a scene, by darkening those areas. Useful for exaggerating detail in a scene.
|
| AO Blend Mode | Simulates natural shadowing that occurs in corners and crevices of a scene, by darkening those areas. Useful for exaggerating detail in a scene.
|
| AO Blend Amount | How much the of AO is applied to the scene, via the Blend Mode chosen. Doesn’t apply to Replace Blend Mode. |
| AO Distance | Controls how wide the Ambient Occlusion radius is. Lower values tighten the ambient occlusion to smaller areas, larger value can end up darkening the whole object, and in some modes add visible noise. |
| AO Falloff Curve | Controls how the weighting of ambient occlusion falls off over distance. Higher values will darken areas of ambient occlusion further, while lower values will lessen the ambient occlusion except in narrow crevices. |
| Radiance Cache | Uses a radiance cache during refinement to speed up rendering. A sparse grid is generated across the entire scene, where the incoming light for all surfaces is cached. The lighting is then approximated over time, allowing subsequent frames to look up lighting from the cache instead of re-calculating it again. Can optimise scenes with lots of lights or lots of geometry, but generally not necessary for pathtraced scenes. |
| Scene Scale | Controls the density of the radiance caches sparse grid. Higher values can make the improve the accuracy of the cache, but increase render time. |
| Lighting Far Plane | Controls the distance away from the camera at which lighting will no longer be calculated. Lower values can increase performance in some scenes, but you’ll need to build the scene such that objects outside this range do not need lighting. |
These properties control how light scattering is processed in the scene.
| Parameter | Details |
|---|---|
| Scattering | Enable raytraced scattering on lights in the scene. Only functions if lights have some scattering amount in use. |
| Scattering Intensity | Multiplier on top of the global scattering density. Useful for adjusting the density globally without going to all the individual lights. |
| Smoke Density | Applies a simple noise pattern over the scattering generated, giving an appearance of smokiness. Useful for generating a mysterious and foggy effect. |
| Smoke Scale | Changes the scale of the smokiness parameters. |
| Smoke Speed | How quickly the generated smoke is animated in the scene. |
| Name | Description | Typical Input |
|---|---|---|
| Probe Separation Distance | TBC | TBC |
| Ray Bias | TBC | TBC |
| Scattering Intensity | TBC | TBC |
| Scattering Max Distance | TBC | TBC |
| AO Distance | TBC | TBC |
| AO Blend Amount | TBC | TBC |
| AO Falloff Curve | TBC | TBC |