RTX - Real-Time mode

Omniverse RTX Renderer provides the RTX - Real-Time ray tracing mode which allows rendering more geometry than traditional rasterization methods as well as physically-based materials at a high fidelity, in real-time.

In RTX - Real-Time mode, the renderer performs a series of separate passes that compute the different lighting contributions (for example: ray-traced ambient occlusion, direct lighting with ray-traced shadows, ray-traced indirect diffuse global illumination, ray-traced reflections, ray-traced translucency and subsurface scattering). Each pass is separately denoised, and the results are composited.

This mode is slightly less accurate than RTX – Interactive (Path Tracing) mode, due to using various shading approximations and optimizations to maintain a high framerate.

Eco Mode

Display Name

Setting Name

Value Type

Default Value

Description

ECO Mode

/rtx/ecoMode/enabled

Bool

True

Pauses frame rendering automatically to reduce GPU usage. This can be particularly useful to reduce power consumption on laptops.

Stop Rendering After This Many Frames Without Changes

/rtx/ecoMode/maxFramesWithoutChange

Int

500

Frame rendering is paused after this many frames without changes, and will resume when a change occurs.

NVIDIA DLSS

Display Name

Setting Name

Value Type

Default Value

Description

Frame Generation

/rtx-transient/dlssg/enabled

Bool

True

DLSS Frame Generation boosts performance by using AI to generate more frames. DLSS analyzes sequential frames and motion data to create additional high quality frames. This feature requires an Ada Lovelace architecture GPU.

Super Resolution

/rtx/post/aa/op

Int

3

Choose between two AI-based algorithms to improve image quality.
- DLSS (3): Boosts performance by using AI to output higher resolution frames from a lower resolution input. DLSS samples multiple lower resolution images and uses motion data and feedback from prior frames to reconstruct native quality images.
- NVIDIA DLAA (4): Provides higher image quality with an AI-based anti-aliasing technique. DLAA uses the same Super Resolution technology developed for DLSS, reconstructing a native resolution image to maximize image quality.
  • Mode

/rtx/post/dlss/execMode

Int

3

Select between Performance, Balanced, Quality, or Auto modes.
- Auto (3): Selects the best DLSS Mode for the current output resolution.
- Quality (2): Offers higher image quality than balanced mode.
- Balanced (1): Offers both optimized performance and image quality.
- Performance (0): Offers a higher performance boost than balanced mode.

Direct Lighting

Display Name

Setting Name

Value Type

Default Value

Description

Direct Lighting

/rtx/directLighting/enabled

Bool

True

Enable direct light contributions from lights.

Samples per Pixel

/rtx/directLighting/sampledLighting/samplesPerPixel

Int

2

Higher values increase the direct lighting quality at the cost of performance.

Max Ray Intensity

/rtx/directLighting/sampledLighting/maxRayIntensity

Float

6400.0

Clamps the brightness of a sample, which helps reduce fireflies, but may result in some loss of energy.

Mesh-Light Sampling

/rtx/directLighting/sampledLighting/ris/meshLights

Bool

False

Enables direct illumination sampling of geometry with emissive materials.

Shadows

/rtx/shadows/enabled

Bool

True

When disabled, lights will not cast shadows.

Indirect Diffuse Lighting

Display Name

Setting Name

Value Type

Default Value

Description

Indirect Diffuse GI

/rtx/indirectDiffuse/enabled

Bool

True

Enables Diffused Global Illumination.

  • Samples per Pixel

/rtx/indirectDiffuse/fetchSampleCount

Int

1

Higher values result in smoother looking GI.

  • Max Bounces

/rtx/indirectDiffuse/maxBounces

Int

2

More bounces allow more potential GI contribution in occluded areas.

  • Intensity

/rtx/indirectDiffuse/scalingFactor

Float

1.0

Controls the intensity of the GI contribution evenly across the occluded area.

Ambient Occlusion

/rtx/ambientOcclusion/enabled

Bool

True

Enables ambient occlusion.

  • Ray Length

/rtx/ambientOcclusion/rayLength

Float

35.0

The radius around the intersection point which the ambient occlusion affects.

  • Minimum Samples per Pixel

/rtx/ambientOcclusion/minSamples

Int

3

Minimum number of samples per frame for ambient occlusion sampling.

  • Maximum Samples per Pixel

/rtx/ambientOcclusion/maxSamples

Int

9

Maximum number of samples per frame for ambient occlusion sampling.

Ambient Light Color

/rtx/sceneDb/ambientLightColor

Float3

0.1,0.1,0.1

Color of the global environment lighting.

Ambient Light Intensity

/rtx/sceneDb/ambientLightIntensity

Float

0.0

Brightness of the global environment lighting.

Reflections

Display Name

Setting Name

Value Type

Default Value

Description

Reflections

/rtx/reflections/enabled

Bool

True

Enables reflections.

Samples per Pixel

/rtx/reflections/sampledLighting/samplesPerPixel

Int

1

Higher values increase the reflections quality at the cost of performance.

Max Ray Intensity

/rtx/reflections/sampledLighting/maxRayIntensity

Float

19200.0

Clamps the brightness of a sample, which helps reduce fireflies, but may result in some loss of energy.

Max Bounces

/rtx/reflections/maxReflectionBounces

Int

1

Number of bounces for reflection rays.

Roughness Cache Threshold

/rtx/reflections/maxRoughness

Float

0.3

Roughness threshold for approximated reflections. Higher values result in better quality, at the cost of performance.

Translucency

Display Name

Setting Name

Value Type

Default Value

Description

Translucency

/rtx/translucency/enabled

Bool

True

Enables translucency for specular transmissive surfaces such as glass.

Max Refraction Bounces

/rtx/translucency/maxRefractionBounces

Int

6

Number of bounces for refraction rays.

Reflection Seen Through Refraction

/rtx/translucency/reflectAtAllBounce

Bool

True

When enabled, reflection seen through refraction is rendered. When disabled, reflection is limited to first bounce only. More accurate, but worse performance.

Fractional Cutout Opacity

/rtx/raytracing/fractionalCutoutOpacity

Bool

False

Enables fractional cutout opacity values resulting in a translucency-like effect similar to alpha-blending.

Depth Correction for DOF

/rtx/translucency/virtualDepth

Bool

False

Improves DoF for translucent refractive objects, but can result in worse performance.

Motion Vector Correction (experimental)

/rtx/translucency/virtualMotion

Bool

True

Enables motion vectors for translucent refractive objects, which can improve temporal rendering such as denoising, but can result in worse performance.

World Epsilon Threshold

/rtx/translucency/worldEps

Float

1.0

Treshold below which image-based reprojection is used to compute refractions. Lower values result in higher quality at the cost performance.

Roughness Sampling (experimental)

/rtx/translucency/sampleRoughness

Bool

False

Enables sampling roughness, such as for simulating frosted glass, but can result in worse performance.

Max Ray Intensity

/rtx/translucency/maxRayIntensity

Float

19200.0

Clamps the brightness of a sample, which helps reduce fireflies, but may result in some loss of energy.

Subsurface Scattering

Display Name

Setting Name

Value Type

Default Value

Description

Subsurface Scattering

/rtx/raytracing/subsurface/enabled

Bool

False

Enables subsurface scattering.

Max Sample Per Frame

/rtx/raytracing/subsurface/maxSamplePerFrame

Int

32

Max samples per frame.

Firefly Filtering

/rtx/raytracing/subsurface/fireflyFiltering/enabled

Bool

True

Enables firefly filtering for the subsurface scattering.

Denoise Irradiance Output

/rtx/directLighting/SampledLighting/irradiance/denoiser/enabled

Bool

False

Denoise the irradiance output from sampled lighting pass before it’s used. Helps in complex lighting conditions or if there are large area lights which makes irradiance estimation difficult with low sampled lighting sample count.

Transmission

/rtx/raytracing/subsurface/transmission/enabled

Bool

True

Enables transmission of light through the medium, but requires additional samples and denoising.

  • BSDF Sample Count

/rtx/raytracing/subsurface/transmission/bsdfSampleCount

Int

1

Transmission sample count per frame.

  • Samples Per BSDF Sample

/rtx/raytracing/subsurface/transmission/perBsdfScatteringSampleCount

Int

1

Transmission samples count per BSDF Sample. Samples per pixel per frame = BSDF Sample Count * Samples Per BSDF Sample.

  • Screen-Space Fallback Threshold

/rtx/raytracing/subsurface/transmission/screenSpaceFallbackThresholdScale

Float

0.1

Transmission threshold for screen-space fallback.

  • Half-Resolution Rendering

/rtx/raytracing/subsurface/transmission/halfResolutionBackfaceLighting

Bool

True

Enables rendering transmission in half-resolution to improve performance at the expense of quality.

  • Sample Guiding

/rtx/raytracing/subsurface/transmission/ReSTIR/enabled

Bool

False

Enables transmission sample guiding, which may help with complex lighting scenarios.

Caustics

Display Name

Setting Name

Value Type

Default Value

Description

Caustics

/rtx/caustics/enabled

Bool

False

Enables simulation of caustics generated for area lights whic have the ‘Enable Caustics’ enabled.

Photon Count Multiplier

/rtx/raytracing/caustics/photonCountMultiplier

Int

20

Factor multiplied by 1024 to compute the total number of photons to generate from each light.

Photon Max Bounces

/rtx/raytracing/caustics/photonMaxBounces

Int

4

Maximum number of bounces to compute for each light/photon path.

Filter Iterations

/rtx/raytracing/caustics/eawFilteringSteps

Int

5

Number of iterations for the denoiser applied to the results of the caustics tracing pass.

Global Volumetric Effects

Display Name

Setting Name

Value Type

Default Value

Description

Accumulation Frames

/rtx/raytracing/inscattering/maxAccumulationFrames

Int

128

Number of frames samples accumulate over temporally. High values reduce noise, but increase lighting update times.

Depth Slices Count

/rtx/raytracing/inscattering/depthSlices

Int

96

Number of layers in the voxel grid to be allocated. High values result in higher precision at the cost of memory and performance.

Pixel Density

/rtx/raytracing/inscattering/pixelRatio

Int

8

Higher values result in higher fidelity volumetrics at the cost of performance and memory (depending on the # of depth slices).

Slice Distribution Exponent

/rtx/raytracing/inscattering/sliceDistributionExponent

Float

3.0

Controls the number (and relative thickness) of the depth slices.

Inscatter Blur Sigma

/rtx/raytracing/inscattering/inscatterUpsample

Int

1

Sigma parameter for the Gaussian filter used to spatially blur the voxel grid. 1 = no blur, higher values blur further.

Inscatter Dithering Scale

/rtx/raytracing/inscattering/ditheringScale

Float

10.0

The scale of the noise dithering. Used to reduce banding from quantization on smooth gradients.

Spatial Sample Jittering Scale

/rtx/raytracing/inscattering/spatialJitterScale

Float

1.0

Scales how far light samples within a voxel are spatially jittered: 0 = only from the center, 1 = the entire voxel’s volume.

Temporal Reprojection Jittering Scale

/rtx/raytracing/inscattering/temporalJitterScale

Float

0.5

Scales how far to offset temporally-reprojected samples within a voxel: 0 = only from the center, 1 = the entire voxel’s volume. Acts like a temporal blur and helps reduce noise under motion.

Use 32-bit Precision

/rtx/raytracing/inscattering/use32bitPrecision

Bool

False

Allocate the voxel grid with 32-bit per channel color instead of 16-bit. This doubles memory usage and reduces performance, generally avoided.

Flow Sampling

/rtx/raytracing/inscattering/enableFlowSampling

Bool

False

Samples density from Flow grid.

  • Min Layer

/rtx/raytracing/inscattering/minFlowLayer

Int

0

Min Flow layer to sample, inclusive.

  • Max Layer

/rtx/raytracing/inscattering/maxFlowLayer

Int

100

Max Flow layer to sample, inclusive.

  • Density Scale

/rtx/raytracing/inscattering/flowDensityScale

Float

250.0

Scale to apply to sampled Flow density.

  • Density Offset

/rtx/raytracing/inscattering/flowDensityOffset

Float

1.0

Offset applied after scale. 1.0 allows existing fog to continue working normally.

Multi-GPU

Multi-GPU rendering in RTX - Real-Time mode splits the image to render as tiles which are dispatched to the GPUs and then composited into a single image.

The primary GPU performs various tasks, such as: rendering pixels, sample aggregation, denoising, post processing, UI rendering. The default GPU 0 Weight value is usually ideal.

Display Name

Setting Name

Value Type

Default Value

Description

Multi-GPU

/rtx/realtime/mgpu/enabled

Bool

True

Enables using multiple GPUs. This splits the rendering of the image into a large tile per GPU with a small overlap region between them.

Automatic Tiling

/rtx/realtime/mgpu/autoTiling/enabled

Bool

True

Automatically determines the image-space grid used to distribute rendering to available GPUs. The image rendering is split into a large tile per GPU with a small overlap region between them. Note that by default not necessarily all GPUs are used. The approximate number of tiles is viewport resolution divided by the Minimum Megapixels Per Tile setting, since at low resolution small tiles distributed across too many devices decreases performance due to multi-GPU overheads. Disable automatic tiling to manually specify the number of tiles to be distributed across devices.

  • Minimum Megapixels Per Tile

/rtx/realtime/mgpu/autoTiling/minMegaPixelsPerTile

Float

0.4

The minimum number of Megapixels each tile should have after screen-space subdivision.

Tile Count

/rtx/realtime/mgpu/tileCount

Int

Auto

Number of tiles to split the image into. Usually this should match the number of GPUs, but can be less.

Tile Overlap (Pixels)

/rtx/realtime/mgpu/tileOverlap

Int

128

Width, in pixels, of the overlap region between any two neighboring tiles.

GPU 0 Weight

/rtx/realtime/mgpu/masterDeviceLoadBalancingWeight

Float

Auto

This normalized weight can be used to decrease the rendering workload on the primary device for each viewport in relation to the other secondary devices, which can be helpful for load balancing in situations where the primary device also needs to perform additional expensive operations such as denoising and post-processing.

Multi-Threading

/rtx/multiThreading/enabled

Bool

True

Execute per-device render command recording in separate threads.

Limitations

For efficiency’s sake, in some contexts rendering will switch to single-GPU automatically until conditions warrant multi-GPU rendering, for example when rendering at low resolution.

Multi-GPU rendering is enabled by default if the system has multiple NVIDIA RTX-enabled GPUs of the same model.

Per-GPU memory usage is limited to 48GB.

Multi-GPU is disabled for mixed-GPU configurations. This can be overridden with a setting. Note that the GPU with the lowest memory capacity will limit the amount of memory the other GPUs can leverage.

GPUs which don’t support ray tracing are skipped automatically.

Note

A GPU information table is logged to the omniverse .log file under [gpu.foundation] listing which GPUs are set as Active. Each GPU has a device index assigned and this index can be used with the multi-GPU settings below.

Setting Name

Value Type

Default Value

Description

/renderer/multiGpu/enabled

Bool

True

Specifies if multi-GPU is enabled, but multi-GPU is disabled if the NVIDIA RTX-enabled GPUs are not of the same model; setting this to true will enable multi-GPU anyway.

/renderer/multiGpu/activeGpus

String

Auto

Enables only a subset of GPUs, specified by a comma-separated list of device indices.

/renderer/multiGpu/maxGpuCount

Int

Auto

Specifies the maximum number of NVIDIA RTX-enabled GPUs. GPUs which don’t support ray tracing are skipped automatically.