RTX Interactive (Path Tracing) Settings

RTX Settings Path-Tracing

RTX Interactive specific render settings.

Anti-Aliasing

RTX PT Settings Anti-Aliasing

Setting

Effect

Anti-Aliasing Sample Pattern

Sampling pattern used for the purposes of Anti-Aliasing. Select between Box,
Triangle, Gaussian and Uniform

Anti-Aliasing Radius

Radius, in pixels, of the sampling footprint to use when generating samples with
the selected antialiasing sample pattern

Firefly Filtering

RTX PT Settings Firefly Filtering

Setting

Effect

Firefly Filtering

Enables logic to reduce the occurrence of “firefly” artifacts

Max Ray Intensity Glossy

The maximum light intensity (in radiance units) that can be contributed along any
one ray for glossy events (when the firefly filter is enabled)

Max Ray Intensity Diffuse

The maximum light intensity (in radiance units) that can be contributed along any
one ray for diffuse events (when the firefly filter is enabled)

Path-Tracing

RTX PT Settings Path-Tracing

Setting

Effect

Max Bounces

Maximum number of bounces in a path

Max Specular and Transmission Bounces

Maximum number of bounces for specular and transmission events

Max SSS Volume Scattering Bounces

Maximum number of bounces for subsurface scattering within a volume

Max Fog Scattering Bounces

Maximum number of bounces for volume scattering within a fog volume

Max Heterogeneous Volume Scattering Bounces

Maximum number of bounces for heterogeneous volumes

Samples per Pixel per Frame (1 to 32)

Total number of samples used for each rendered pixel in one frame update

Total Samples per Pixel (0 = inf)

Maximum number of samples to accumulate per pixel. When this sample count is reached
the rendering stops and the same image is displayed until a scene or setting change
is detected, causing the rendering process to restart. Set to 0 to remove this limit.

Enable Fractional Cutout Opacity

If enabled, fractional cutout opacity values are treated as a measure of surface
‘presence’, resulting in a translucency effect similar to alpha-blending.
Path-traced mode uses stochastic sampling based on these values to determine whether
a surface hit is valid or should be skipped.

Reset Accumulation on Time Change

If enabled, the Path-Tracer accumulation is restarted every time the MDL animation
time changes. Settings this to false is useful to prevent accumulation reset at every
frame when the ‘animation time’ is changing every frames using wallclock time
(which can be the case when we an animation is not being played, and
wallclock time is used instead of animation time)

Note

While using a higher number of bounces increases accuracy of the final image, it can quickly reduce performance while achieving diminishing returns in terms of image quality.

Sampling & Caching

RTX PT Settings Sampling & Caching

Setting

Effect

Enable Caching

Enables a technique that caches path tracing results for improved performance
at the cost of some correctness.

Enable Many-Light Sampling

Enables a technique that improves the sampling quality (and therefore rendering convergence)
in scenes with many light primitives

Denoising

RTX PT Settings Denoise

Setting

Effect

Denoising

Enable to apply the OptiX Denoiser to the radiance image generated by the renderer.
The OptiX denoiser results in an order of magnitude reduction in rendering times for
a target image quality.

Optix Denoiser Blend Factor

A blend factor indicating how much to blend the denoised image with the original non-denoised image.
A value of 0 shows only the denoised image, while a value of 1.0 shows the image with no denoising applied.

Path-Traced Fog

RTX PT Settings Path-Traced Fog

Setting

Effect

Path-Traced Fog

Enables Path-Traced fog using volume absorption and scattering simulation with a
Henyey-Greenstein phase function
The number of bounces is controlled by Max Fog Scattering Bounces

Density

The density of the fog medium

Height

The maximum height of the fog volume

Falloff

Exponential fall-off of the fog

Color

The color of the fog medium

Asymmetry (g)

The asymmetry of the Henyey-Greenstein phase function (“g” parameter)

Use +Z Axis for Height

If set the volume height is considered along the positive Z. Otherwise use the
positive Y axis

Heterogeneous Volumes

This feature enables path-traced volume rendering of both VDB files (internally converted to NanoVDB, a faster and more compact GPU-friendly volume representation) and procedural MDL based volumes. VDB files can either contain a SDF (signed distance field/level set) or density volume. Currently, the VDB volume material can only be applied to a cube mesh, while procedural volume materials can be applied to any kind of mesh (cube, sphere, torus, etc). Volumes can also overlap with other volumes. The maximum number of overlaps between the volumes is currently limited to four.

How to create a VDB volume object

  • Create a cube mesh

  • In the cube’s Property tab, check isVolume

  • Assign VDBTestMaterial.mdl to the cube

  • In the Property tab of the VDBTestMaterial, assign a VDB file to the volume_density_texture

How to create a procedural volume object

  • Create a cube mesh

  • In the cube’s Property tab, check isVolume

  • Assign either perlinNoise.mdl or worleyNoise.mdl to the cube

RTX PT Settings Path-Traced Heterogenous_Volumes

Setting

Effect

Heterogeneous Volumes

The number of bounces is controlled by Max Heterogeneous Volume Scattering Bounces (under the Path-Tracing section in Path-Traced Mode Settings).
• When set to 1: perform single scattering. Fast, suitable for lowly scattering volumes like fog.
• When set to a value greater than 1: perform multi-scattering. Slower, suitable for highly scattering volumes like clouds.
Important: Make sure to increase the number of bounces to avoid darkening artifacts.

Transmittance Method

Choose between Biased Ray Marching, Ratio Tracking or Brute-Force Ray Marching. Biased ray marching is the ideal option in all cases.

Max Collision Count

Maximum delta tracking iterations. Increase to more than 32 for highly scattering volumes like clouds.
Important: if set too low, parts of the volume will disappear.

Max Light Collision Count

Maximum ratio tracking iterations. Increase to more than 32 for highly scattering volumes like clouds.
Important: if set too low, parts of the volume will disappear.

Max Density

Upper bound of the density of the volume (called Global Majorant in volume rendering).
Important: if set too low, the volume will appear overly transparent.

Fast VDB

Accelerates volume rendering of VDB files by 3-6x at the same accuracy. This setting does not work with MDL based volumes.

Multi-GPU

RTX PT Settings Multi-GPU

Setting

Effect

Multi-GPU

Enables the use of multiple GPUs in path-traced mode (when these are available and enabled at startup)
Multi-GPU must be enabled at startup by passing adding –/renderer/multiGpu/enabled=true to the command line

GPU 0 Weight

The amount of total Path-Tracing work (between 0 and 1) to be performed by the first
GPU in a Multi-GPU configuration. A value of 1 means the first GPU will perform the
same amount of work assigned to any other GPU.

Compress Radiance

Enables lossy compression of per-pixel output radiance values

Compress Albedo

Enables lossy compression of per-pixel output albedo values (needed by OptiX denoiser)

Compress Normals

Enables lossy compression of per-pixel output normal values (needed by OptiX denoiser)