User Guide Cancel

Iray | Substance 3D Designer

  1. Substance 3D home
  2. User guide
  3. Glossary
  4. Getting started
    1. Getting started
    2. Activation and licenses
    3. System requirements
    4. Overview
      1. Overview
      2. What is a Substance 3D file?
    5. Workflow overview
    6. Shortcuts
    7. Tutorials & learning
  5. Interface
    1. Interface
    2. Customizing your workspace
    3. Home screen
    4. Main toolbar
    5. Preferences
      1. Preferences
      2. Project settings
      3. Version control
    6. Explorer
      1. Explorer
      2. Send to... / Interoperability
    7. Graph view
      1. Graph view
      2. Link creation modes
      3. Graph items
        1. Graph items
        2. Dot node (also Portal)
        3. Frame
        4. Comment
        5. Pin
    8. Library
      1. Library
      2. Managing custom content and filters
    9. Properties
    10. 2D view
    11. 3D view
      1. 3D view
      2. Material properties
      3. GLSLFX shaders
      4. Switching your shaders to OpenGL Core Profile
      5. Iray
    12. Dependency manager
  6. Resources
    1. Resources
    2. Importing, linking and new resources
    3. Bitmap resource
      1. Bitmap resource
      2. Bitmap painting tools
    4. Vector graphics (SVG) resource
      1. Vector graphics (SVG) resource
      2. Vector editing tools
    5. 3D scene resource
    6. AxF (Appearance eXchange Format)
    7. Font resource
    8. Warnings from dependencies
  7. Substance graphs
    1. Substance graphs
    2. Substance graph key concepts
    3. Creating a Substance graph
      1. Creating a Substance graph
      2. Graph instances / Sub-graphs
    4. Exposing a parameter
      1. Exposing a parameter
      2. Parameter presets
      3. Visible if: control visibility of inputs, outputs and parameters
    5. Graph parameters
    6. Inheritance in Substance graphs
    7. Output size
    8. Values in Substance graphs
    9. Publishing Substance 3D asset files (SBSAR)
    10. Exporting bitmaps
    11. Exporting PSD files
    12. Sample Substance graphs
    13. Warnings in Substance graphs
    14. Nodes reference for Substance graphs
      1. Nodes reference for Substance graphs
      2. Atomic nodes
        1. Atomic nodes
        2. Bitmap
        3. Blend
          1. Blend
          2. Blending modes description
        4. Blur
        5. Channel shuffle
        6. Curve
        7. Directional blur
        8. Directional warp
        9. Distance
        10. Emboss
        11. FX-map
        12. Gradient (Dynamic)
        13. Gradient map
        14. Grayscale conversion
        15. HSL
        16. Levels
        17. Normal
        18. Pixel processor
        19. SVG
        20. Sharpen
        21. Text
        22. Transformation 2D
        23. Uniform color
        24. Value processor
        25. Warp
        26. Output
        27. Input
      3. Node library
        1. Node library
        2. Texture generators
          1. Texture generators
          2. Noises
            1. Noises
            2. 3D Perlin noise
            3. 3D Perlin noise fractal
            4. 3D Ridged noise fractal
            5. 3D Simplex noise
            6. 3D Voronoi
            7. 3D Voronoi fractal
            8. 3D Worley noise
            9. Anisotropic noise
            10. Blue noise fast
            11. BnW spots 1
            12. BnW spots 2
            13. BnW spots 3
            14. Cells 1
            15. Cells 2
            16. Cells 3
            17. Cells 4
            18. Clouds 1
            19. Clouds 2
            20. Clouds 3
            21. Creased
            22. Crystal 1
            23. Crystal 2
            24. Directional noise 1
            25. Directional noise 2
            26. Directional noise 3
            27. Directional noise 4
            28. Directional scratches
            29. Dirt 1
            30. Dirt 2
            31. Dirt 3
            32. Dirt 4
            33. Dirt 5
            34. Dirt gradient
            35. Fluid
            36. Fractal sum 1
            37. Fractal sum 2
            38. Fractal sum 3
            39. Fractal sum 4
            40. Fractal sum base
            41. Fur 1
            42. Fur 2
            43. Fur 3
            44. Gaussian noise
            45. Gaussian spots 1
            46. Gaussian spots 2
            47. Grunge concrete
            48. Grunge Damas
            49. Grunge galvanic large
            50. Grunge galvanic small
            51. Grunge leaks
            52. Grunge leaky paint
            53. Grunge map 001
            54. Grunge map 002
            55. Grunge map 003
            56. Grunge map 004
            57. Grunge map 005
            58. Grunge map 006
            59. Grunge map 007
            60. Grunge map 008
            61. Grunge map 009
            62. Grunge map 010
            63. Grunge map 011
            64. Grunge map 012
            65. Grunge map 013
            66. Grunge map 014
            67. Grunge map 015
            68. Grunge rough dirty
            69. Grunge rust fine
            70. Grunge scratches dirty
            71. Grunge scratches fine
            72. Grunge scratches rough
            73. Grunge shavings
            74. Grunge splashes dusty
            75. Grunge spots
            76. Grunge spots dirty
            77. Liquid
            78. Messy fibers 1
            79. Messy fibers 2
            80. Messy fibers 3
            81. Microscope view
            82. Moisture noise
            83. Perlin noise
            84. Plasma
            85. Caustics
            86. Voronoi
            87. Voronoi fractal
            88. Waveform 1
            89. White noise
            90. White noise fast
          3. Patterns
            1. Patterns
            2. 3D linear gradient
            3. 3D volume mask
            4. Alveolus
            5. Arc pavement
            6. Brick 1
            7. Brick 2
            8. Brick generator
            9. Checker 1
            10. Cube 3D
            11. Cube 3D GBuffers
            12. Fibers 1
            13. Fibers 2
            14. Gaussian 1
            15. Gaussian 2
            16. Gradient axial
            17. Gradient axial reflected
            18. Gradient circular
            19. Gradient linear 1
            20. Gradient linear 2
            21. Gradient linear 3
            22. Gradient radial
            23. Height extrude
            24. Mesh 1
            25. Mesh 2
            26. Panorama shape
            27. Polygon 1
            28. Polygon 2
            29. Scratches generator
            30. Shape
            31. Shape extrude
            32. Shape mapper
            33. Shape splatter
            34. Shape splatter blend
            35. Shape splatter data extract
            36. Shape splatter to mask
            37. Splatter
            38. Splatter circular
            39. Star
            40. Starburst
            41. Stripes
            42. Tile generator
            43. Tile random
            44. Tile random 2
            45. Tile sampler
            46. Triangle grid
            47. Weave 1
            48. Weave 2
            49. Weave generator
        3. Filters
          1. Filters
          2. Adjustments
            1. Adjustments
            2. Auto levels
            3. Channel mixer
            4. Chrominance extract
            5. Clamp
            6. Color match
            7. Color to mask
            8. Contrast/Luminosity
            9. Convert to linear
            10. Convert to sRGB
            11. Grayscale conversion advanced
            12. Hald CLUT
            13. HDR range viewer
            14. Height map frequencies mapper
            15. Highpass
            16. Histogram range
            17. Histogram scan
            18. Histogram scan non-uniform
            19. Histogram select
            20. Histogram shift
            21. Invert
            22. Lighting cancel high frequencies
            23. Lighting cancel low frequencies
            24. Luminance highpass
            25. Min max
            26. Pow
            27. Quantize
            28. Replace color
            29. Replace color range
            30. Threshold
          3. Blending
            1. Blending
            2. Color (Blend node)
            3. Color burn
            4. Color dodge
            5. Difference
            6. Dissolve
            7. Linear burn
            8. Luminosity (Blend node)
            9. Multi switch
            10. Switch
          4. Blurs
            1. Blurs
            2. Anisotropic blur
            3. Blur HQ
            4. Non uniform blur
            5. Radial blur
            6. Slope blur
          5. Channels
            1. Channels
            2. RGBA merge
            3. RGBA split
            4. Alpha merge
            5. Alpha split
            6. Pre-multiplied to straight
            7. Straight to pre-multiplied
          6. Effects
            1. Effects
            2. 3D texture position
            3. 3D texture SDF
            4. 3D texture surface render
            5. 3D texture volume render
            6. Ambient occlusion (HBAO)
            7. Ambient occlusion (RTAO)
            8. Bevel
            9. Cross section
            10. Curvature
            11. Curvature smooth
            12. Curvature sobel
            13. Diffusion color
            14. Diffusion grayscale
            15. Diffusion UV
            16. Edge detect
            17. Emboss with gloss
            18. Extend shape
            19. Flood fill
            20. Flood fill mapper
            21. Flood fill to Bbox size
            22. Flood Fill to gradient
            23. Flood Fill to grayscale/color
            24. Flood Fill to index
            25. Flood Fill to position
            26. Flood Fill to random color
            27. Flood Fill to random grayscale
            28. FXAA
            29. Glow
            30. Mosaic
            31. Multi directional warp
            32. Non uniform directional warp
            33. Reaction diffusion fast
            34. RT irradiance
            35. RT shadow
            36. Shadows
            37. Shape drop shadow
            38. Shape glow
            39. Shape stroke
            40. Summed area table
            41. Swirl
            42. Uber emboss
            43. Vector morph
            44. Vector warp
          7. Normal map
            1. Normal Map
            2. Bent Normal
            3. Facing Normal
            4. Height Normal Blender
            5. Height to Normal World Units
            6. Normal Blend
            7. Normal Combine
            8. Normal Invert
            9. Normal Normalize
            10. Normal Sobel
            11. Normal to Height
            12. Normal To Height HQ
            13. Normal Transform
            14. Normal Vector Rotation
          8. Tiling
            1. Tiling
            2. Make It Tile Patch
            3. Make It Tile Photo
          9. Transforms
            1. Transforms
            2. 3D Texture Offset
            3. Auto Crop
            4. Cartesian To Polar
            5. Clone (Filter Node)
            6. Mirror (Filter Node)
            7. Noise Upscale 1
            8. Noise Upscale 2
            9. Noise Upscale 3
            10. Non-Square Transform
            11. Non-Uniform Rotation
            12. Polar to Cartesian
            13. Quad Transform
            14. Safe Transform
            15. Skew
            16. Symmetry
            17. Symmetry Slice
            18. Trapezoid Transform
        4. Material filters
          1. Material filters
          2. 1-click
            1. 1-Click
            2. Bitmap to Material Light
          3. Effects (Material)
            1. Effects (Material)
            2. Height Blend
            3. Material Height Blend
            4. Season Filter
            5. Snow Cover
            6. Water Level
          4. Transforms (Material)
            1. Transforms (Material)
            2. Material Transform
          5. Blending (Material)
            1. Blending (Material)
            2. Material Adjustment Blend
            3. Material Blend
            4. Material Color Blend
            5. Material Switch
            6. Multi-Material Blend
          6. PBR utilities
            1. PBR Utilities
            2. BaseColor / Metallic / Roughness converter
            3. Base Material
            4. PBR Albedo Safe Color
            5. PBR BaseColor / Metallic Validate
            6. PBR Dielectric F0
            7. PBR Metal Reflectance
            8. PBR Render
            9. PBR Render Mapping
          7. Scan processing
            1. Scan Processing
            2. AO Cancellation
            3. Atlas Scatter
            4. Atlas Splitter
            5. Clone Patch
            6. Color Equalizer
            7. Crop
            8. Material Clone Patch
            9. Material Crop
            10. Multi-Angle to Albedo
            11. Multi-Angle to Normal
            12. Multi Clone Patch
            13. Multi Color Equalizer
            14. Multi Crop
            15. Smart Auto Tile
        5. Mesh-based generators
          1. Mesh-based generators
          2. Mask generators
            1. Mask Generators
            2. Bottom To Top
            3. Cloth Wear
            4. Dirt
            5. Dripping Rust
            6. Dust
            7. Edge Blur
            8. Edge Damages
            9. Edge Dirt
            10. Edge Notch
            11. Edge Select
            12. Edge Speckle
            13. Edge Wear
            14. Fiber Glass Edge Wear
            15. Grease
            16. Ground Dirt
            17. Leaks
            18. Leather Wear
            19. Light
            20. Mask Builder
            21. Metal Edge Wear
            22. Paint Wear
            23. Selective Dirt
            24. Sun Bleach
            25. Surface Brush
          3. Weathering
            1. Weathering
            2. Cracks Weathering
            3. Fabric Weathering
            4. Leather Weathering
            5. Metal Weathering
            6. Moss Weathering
            7. Rock Weathering
            8. Rust Weathering
          4. Utilities (Mesh-based generators)
            1. Utilities (Mesh Based Generators)
            2. 3D Planar Projection
            3. Material Mesh Data Blender
            4. Material Selector
            5. Mesh Data Combiner
            6. Tri Planar
        6. Spline & Path tools
          1. Spline & Path tools
          2. Working with Path & Spline tools
          3. Path tools
            1. Path Tools
            2. Paths Format Specifications
            3. Paths 2D Transform
            4. Mask to Paths
            5. Paths to Spline
            6. Paths Polygon
            7. Preview Paths
            8. Paths Warp
            9. Quad Transform on Path
            10. Paths Select
            11. Paths Vertex Processor
            12. Paths Vertex Processor Simple
          4. Spline tools
            1. Spline Tools
            2. Paths to Spline
            3. Point List
            4. Scatter on Spline Color
            5. Scatter on Spline Grayscale
            6. Spline 2D Transform
            7. Spline (Cubic)
            8. Spline (Poly Quadratic)
            9. Spline Append
            10. Spline Bridge (2 Splines)
            11. Spline Bridge (List)
            12. Spline Bridge Mapper Color
            13. Spline Bridge Mapper Grayscale
            14. Spline Circle
            15. Spline Fill
            16. Spline Flow Mapper
            17. Spline Mapper Color
            18. Spline Mapper Grayscale
            19. Spline Merge List
            20. Spline Render
            21. Spline Sample Height
            22. Spline Sample Thickness
            23. Spline Select
            24. Spline Warp
            25. UV Mapper Color
            26. UV Mapper Grayscale
        7. 3D view (Library)
          1. 3D view (Library)
          2. HDRI tools
            1. HDRI Tools
            2. Blackbody
            3. Color Temperature Adjustment
            4. Exposure
            5. Exposure Preview
            6. HDR Merge
            7. Nadir Extract
            8. Nadir Patch
            9. Panorama 3D Position
            10. Panorama Rotation
            11. Gradient 2 Points
            12. Gradient Linear (HDRI)
            13. Line Light
            14. Physical Sun/Sky
            15. Plane Light
            16. Shape Light
            17. Sphere Light
            18. Straighten Horizon
  8. Substance function graphs
    1. Substance function graphs
    2. What is a Substance function graph?
    3. Create and edit a Substance function graph
    4. The Substance function graph
    5. Variables
      1. Variables
      2. Built-in variables
      3. Get a variable value
      4. Create a variable
    6. FX-maps
      1. FX-Maps
      2. How it works
      3. The Iterate node
      4. The Quadrant node
      5. Using Substance function graphs in FX-Maps
        1. Using Substance function graphs
          in FX-Maps
        2. Iterate and $number variable
        3. Using the Sampler nodes
        4. Using the Set/Sequence nodes
    7. Warnings in Substance function graphs
    8. Sample Substance function graphs
    9. Nodes reference for Substance function graphs
      1. Nodes reference for Substance function graphs
      2. Function nodes overview
      3. Constant nodes
      4. Vector and Swizzle nodes
      5. Get nodes
      6. Sampler nodes
      7. Cast nodes
      8. Operator nodes
      9. Logical nodes
      10. Comparison nodes
      11. Function nodes
      12. Control nodes
  9. MDL graphs
    1. MDL graphs
    2. Main MDL graph concepts
    3. Creating an MDL graph
    4. MDL library
    5. Exposing parameters in MDL graphs
    6. Substance graphs and MDL materials
    7. Exporting MDL content
    8. Warnings in MDL graphs
    9. MDL learning resources
  10. Bakers
    1. Bakers
    2. Bakers legacy interface
  11. Best practices
    1. Best practices
    2. Filesize reduction guidelines
    3. Graph creation etiquette
    4. Performance optimization guidelines
  12. Pipeline and project configuration
    1. Pipeline and project configuration
    2. Project configuration files - SBSPRJ
    3. Configuration list - SBSCFG
    4. User preferences - Automating setup
    5. Retrieving the installation path
    6. Environment variables
  13. Color management
    1. Color management
    2. Spot colors (Pantone)
  14. Package metadata
  15. Scripting
    1. Scripting
    2. Plugin basics
    3. Plugin search paths
    4. Plugins packages
    5. Plugin manager
    6. Python editor
    7. Accessing graphs and selections
    8. Nodes and properties
    9. Undo and redo
    10. Application callbacks
    11. Creating user interface elements
    12. Adding actions to the Explorer toolbar
    13. Using color management
    14. Using spot colors
    15. Logging
    16. Using threads
    17. Debugging plugins using Visual Studio Code
    18. Porting previous plugins
    19. Packaging plugins
    20. Scripting API reference
  16. Technical issues
    1. Technical issues
    2. Warnings and errors
    3. Cannot create/load a project
    4. Application does not start
    5. Crash when rendering graphs
    6. Parameters not working as expected
    7. Incorrect image output
    8. 3D View issues
    9. User interface issues
    10. Python issues
    11. Substance model graph feature is missing
  17. Release notes
    1. Release notes
    2. All changes
    3. Version 13.1
    4. Version 13.0
    5. Version 12.4
    6. Version 12.3
    7. Version 12.2
    8. Version 12.1
    9. Version 11.3
    10. Version 11.2
    11. Version 2021.1 (11.1)
    12. Old versions
      1. Old versions
      2. Version 2020.2 (10.2)
      3. Version 2020.1 (10.1)
      4. Version 2019.3 (9.3)
      5. Version 2019.2 (9.2)
      6. Version 2019.1 (9.1)


This pages presents the Iray renderer available in the 3D view panel of Substance 3D Designer, which offers interactive path tracing for photorealistic rendering with CPU and/or GPU acceleration (Nvidia GPUs only).

In this page


Iray is a highly interactive and intuitive physically based rendering technology that generates photorealistic imagery by simulating the physical behaviour of light and materials. Learn more on the Nvidia Iray webpage.

NVIDIA Iray logo

As the 3D View uses Iray's progressive renderer, an image is produced as soon as at least one sample has been performed on each pixel. The image is automatically updated as sampling iterations are performed, resulting in an initial rough image becoming cleaner on each iteration.

The renderer is available in the 3D view panel: open the Renderer menu and select the Iray option to switch the renderer used in that 3D view panel to Iray.
Switching to the Iray renderer changes the available options in some of the 3D view menus. These changes are explained in the 3D view section below.

By default, progressive rendering starts as soon as the Iray renderer is selected. The rendering process will run until one of these conditions is met:

  • The maximum number of samples are performed
  • The rendering time limit is met

See the Renderer section of this page to learn more about tweaking these conditions.

Medieval castle wall material rendered in Iray

Material: Medieval castle wall by Mark Foreman available in our Substance 3D assets library


Only one Iray rendering instance can be run at any time.
This means when a 3D view panel uses this renderer, the Renderer menu is disabled in other 3D view panels and these default to the OpenGL renderer.

3D view options

The following options are available for adjusting the rendered scene:


Select the Edit option in the Scene menu to find scene properties specific to Iray in the Properties panel.

  • Is enabled: When set to False, the object is hidden and no longer contributes to the scene

Display component

  • Is visible: When set to False, the object is hidden yet still contributes to the scene – i.e. reflecting light, absorbing light and projecting shadows

Mesh display component

  • Subdivision
    • Method: The method used to procedurally subdivide the mesh into finer geometry
      • None: No subdivision is applied
      • Parametric: Subdivides the mesh into 4^x triangles where x is the value specified by this parameter
      • Length: Subdivides the mesh until all edges have a length (in object space) below the value specified by the Minimum length parameter
    • Minimum length: Subdivides the mesh until all edges have a length below this specified value in object space (only applies to the Length method)
    • Number: The number of subdivision iterations which should be applied to the mesh (only applies to the Parametric method)

Subdividing the mesh increases its processing time exponentially before and during the render. We suggest being conservative with the values input.
Be careful about using high Number values for the Parametric method, and low Minimum length values for the Length method.

Scene options


Since Iray relies on the MDL shading model developed by NVIDIA, available materials for scene materials are replaced with the MDL library loaded by Designer. This library is built using the following sources:

For a deeper look into the MDL shading model, check out the MDL Handbook, written and maintainted by NVIDIA.

The cumulative list of loaded MDL materials is availabe in the Materials menu, under any of the listed materials' submenu as shown in the image on the right.

Additionally, if an MDL graph is loaded in Designer, it can be applied to any material in the Scene. At that point, it is added to the list of available MDL materials.

Other notable options in this menu are:

  • Select the Edit option to access the MDL's exposed inputs in the Properties panel and tweak the material as required
  • The Load... option lets you manually load any MDL file to be added to the cumulative list and applied in the scene
  • The Export Preset... option opens the Export MDL Material Preset dialog, which lets you export a preset MDL file using the current settings applied in the 3D View
Materials menu


When loading an MDL graph, the 3D view renderer is automatically switched to Iray to load and apply it.


The main difference between OpenGL and Iray regarding camera settings is how depth of field is managed. Indeed, Iray being a physically-accurate renderer, depth of field occurs "naturally" depending on the camera's aperture.

The following couple of parameters are available in the camera properties when the Iray renderer is selected:

  • Focus distance: the distance from the camera of the focal point – i.e. where the image is at its sharpest
  • Aperture diameter: the value driving the camera's aperture. The lower the value, the sharper the image elements are before and after the focal point – in simpler terms, this value controls the strength of the depth of field effect
Camera settings


Open the Environment menu and select the Edit option to display the environment properties in the Properties panel.

The following properties are available:


  • Dome type: sets the objects enclosing the scene, which the environment texture is projected on
    • Infinite sphere: infinite spherical environment
    • Ground: infinite spherical environment, but with a textured ground plane
    • Sphere: finite size sphere-shaped dome of custom radius
    • Sphere with ground: finite size sphere-shaped dome with custom radius where the lower part of the environment is projected onto the plane dividing upper and lower parts of the sphere
    • Box with ground: finite size box-shaped dome of custom width, height and length where the lower part of the environment is projected onto the plane dividing upper and lower parts of the box
  • Rotation angle: controls the angle of rotation of the dome around the Y axis
  • Radius: the radius of the sphere (only applies to the Sphere and Sphere with ground dome types)
  • Width: the width of the box (only applies to the Box with ground dome type)
  • Height: the height of the box (only applies to the Box with ground dome type)
  • Length: the length of the box (only applies to the Box with ground dome type)
  • Visualize: enables a false-color overlay of the finite size environment geometry. This can be used to align the geometry with the projection of the captured environment map (only applies to the Sphere, Sphere with ground and Box with ground dome types)

For finite size domes, all scene geometry should be enclosed within the dome.

Dome ground
The following parameters apply to the Ground, Sphere with ground and Box with ground dome types:

  • Ground: enables the ground plane
  • Position: the position of the origin of the finite dome (also applies to the Sphere dome type)
  • Reflectivity: the opacity and tint of the ground reflection, where black means the reflection is not visible
  • Glossiness: the glossiness of the ground reflection
  • Shadow intensity: the opacity of the shadow cast on the ground
  • Texture scale: controls the size of the environment texture projection on the ground (also applies to the Sphere dome type)

The impact of some of these settings is demonstrated below:

Iray - Environment hidden
Iray - Environment visible
Iray - Infinite sphere only
Iray - Infinite sphere with ground plane
Rotate environment

Ground reflection

Environment scale (sphere)

Environment scale (cube)


These options display a text overlay on top of the rendered image with useful information regarding the render.

  • Elapsed time: The duration of the render in seconds. This timer and the rendering process will both stop when one of the ending conditions are met
  • Iterations: The number of sampling iterations performed. This counter and the rendering process will both stop when one of the ending conditions are met
  • Rendering method: The rendering pathway used. For most purposes on a local machine, Photoreal is used
  • Resolution: The effective rendering resolution. If the Use window resolution option in the camera properties is set to False, the ratio of the image is automatically adjusted to match the resolution ratio
  • Scene stats: A list of statistics related to the rendered scene, which includes triangles count, and materials count among other data
Display options


Open the Renderer menu and select the Edit option to display the renderer properties in the Properties panel.

Progressive rendering

  • Min samples: The minimum number of samples per pixel to compute before considering criteria to stop progressive rendering
  • Max samples: If this number of samples per pixel has been rendered, then stop progressive rendering automatically
  • Max time (seconds): Time in seconds after which progressive rendering should terminate automatically
  • Caustic sampler enabled: Augment the default sampler with a dedicated caustic sampler. Caustics are a result of light passing through a non-opaque object, thus is required only if an MDL material supporting translucency is applied on any object in the scene

  • Firefly filter enabled: enable the firefly filter, which uses a predefined algorithm to remove fireflies in the computed image as rendering progresses. Fireflies are visual artifacts where isolated pixels in an image which are noticeably brighter than their neighbours, and are a result of unsufficient ray samples to accurately determine the distribution of light
  • Post denoiser
    The Iray renderer uses the NVIDIA Optix AI-Accelerated denoiser algorithm for iterative high-quality denoising of the image as it is being rendered.

    • Enabled: enables a predefined denoising algorithm to be triggered at a set rendering iteration, and be active until the end of the render
    • Start iteration: If the denoiser is enabled, this option sets the iteration at which the denoising process starts. This can prevent the denoiser's performance overhead from impacting interactivity, for example, when moving the camera. Additionally, the first few iterations are often not suitable as input for the denoiser due to insufficient convergence, leading to unsatisfactory results.

The impact of some of these settings is demonstrated in the image comparisons below:

Iray - Base render
Iray - Caustic sampler enabled
Iray - Firefly filter disabled
Iray - Firefly filter enabled
Iray - Post-denoiser disabled
Iray - Post-denoiser enabled

Material: Thick glass MDL available in the MDL Core definitions by NVIDIA

Hardware acceleration

The Iray renderer offers hardware acceleration on NVIDIA GPUs exclusively, which offers the following benefits:

You may select the hardware which should be used by Iray for rendering in the 3D View section of the Preferences window, as shown in the image on the right.

When a supported GPU is detected, it is listed in this section, is automatically selected by default and the CPU is unselected. Any manual change overrides this automatic behaviour so your custom changes are saved for future sessions.


If a supported GPU is detected and listed, we strongly recommend leaving the CPU unselected as using the CPU for Iray rendering has a significant impact on the overall performance and responsiveness of the application.


GPU hardware acceleration uses the NVIDIA CUDA technology. Make sure your graphics driver is up-to-date for the best compatibility and reliability. Find the most recent driver for your NVIDIA GPU here.
For multi-GPUs configurations, it is recommended to disable SLI and select only one GPU for the best reliability.

Iray preferences


Get help faster and easier

New user?