Iray

Patchwork 3D Design includes Iray, a physically realistic raytracing engine designed to work with Nvidia graphics cards. Iray provides an interactive rendering with progressive refinement, which approximates the physically realistic behavior of light and its interaction with materials. Among other advantages, this allows for the use of effects such as global illumination.

In Patchwork 3D Design, modifications to Iray-specific settings are saved in the database. If an Iray database is later opened by an equivalent version of Patchwork 3D Design that does not include the Iray module, the Iray settings will be ignored, but will be preserved.

Conversion of a Patchwork 3D scene for Iray

The various elements in a Patchwork 3D Design are converted for rendering with Iray, with certain limitations. The following elements are not converted, or are only partially converted:

• Environment type materials
• Labels in Add and Multiply modes
• Video textures: supported in video snapshots only
• Overlays
• Post-processing produced by Patchwork 3D Design

Rendering with Iray

To start a render using Iray, enable Iray rendering with the button. Rendering will begin in the active viewport.

To increase interactivity, you may choose to keep the Patchwork 3D Design rendering in the active viewport and to send the Iray rendering to a remote window. To do so:

1. Open the Iray settings editor
2. Enable the rendering in a remote window with the button
3. If the remote window is hidden, show it by clicking on the button

During refinement, the number of passes and the current rendering time are displayed at the top of the Iray settings editor and at the top of the remote Iray rendering window, if the remote window is enabled.

A message is also displayed in the Patchwork 3D Design status bar when refinement has finished.

Activation and viewing controls

In the Matter interface:

Icon	Function
	Enable Iray rendering
	Pause refinement
	Show the Iray settings editor

In the Iray settings editor:

Icon	Function
	Enable Iray rendering in a remote window
	Show / hide the remote rendering window
	Synchronize the aspect ratio of the remote rendering window with that of the active viewport
	Show the remote rendering window in full screen. To quit the full screen mode, press the Esc key
	Show the rendering log
	Access connections to remote rendering servers

Scene

Iray Rendering Modes

You can choose from among the standard Iray rendering modes.

Iray Photoreal: This is the photo- and physically realistic mode in Iray, which uses complex global illumination effects. This mode offers a maximum quality but takes longer to calculate the refinement of the image.

Iray Interactive: This raytracing mode uses progressive rendering that allows you to take advantage of the effects of a raytracer without giving up interaction and editing capabilities. This mode does not provide physically realistic rendering.

Blend: Render convergence begins in Interactive mode and then switches to Photoreal mode after a certain level of refinement is achieved. In high-interactivity situations, this mode allows for more fluid interaction while still aiming for increased realism once the interaction has ended. Because both rendering modes are used, this mode consumes more memory resources during the conversion of the scene.

Refinement stop criteria

Multiple criteria are available to define the end of the refinement phase. The rendering will stop as soon as the first limit is reached.

Max samples per pixel: the higher the limit, the better the quality and the longer the rendering time

Max quality: expressed as the rate of convergence per pixel, from 0 to 1, where 1 represents an infinite convergence

Max time: maximum duration of the calculation in hours, minutes and seconds before stopping the refinement

Max path length: in number of bounces

Render Settings

The optimization settings favor certain phenomenons or characteristics that are physically present in the scene in order to make the final convergence for these elements visible earlier during the rendering.

Caustic sampler: uses a sampling strategy to favor the calculation of caustics

Architecture sampler: allows earlier appearance of the light in interior spaces

Ground

The ground, when enabled, simulates an infinite plane, covered in the equivalent of a matte material. In background mode, it includes the reflections of and influence of the product's environment.

Altitude: height of the ground along the Y axis

Shadow intensity

Scale: adjusts the scale of the environment

Glossiness: glossiness of the ground

Reflectivity: reflection color for the ground

Filtering Settings

Filters reduce certain artifacts associated with the non-convergence of pixels. Filters can impose an additional calculation load, which can taken up, in part, by the CPU.

Fireflies: filters bright points

Degrain filtering: produces a smoothing of the rendering. Five modes are available:

• Pixel clipping
• Smart median
• Smart average
• Limited blur
• Limited auto blur

In ascending order, the Pixel clipping produces a soft smoothing while the Limited auto blur produces a strong smoothing.

Denoise filtering

The Patchwork 3D rendering engine supports NVIDIA Iray's new intelligent noise reduction algorithms.
During the progressive refinement it is now possible to obtain a rendering without noise from a threshold defined in advance.

From the user-defined threshold of the Minimum iterations, intelligent noise reduction algorithms perform a process to make the image look sharper.

• The higher the threshold, the more intelligent noise reduction occurs late in rendering.
• The lower the threshold, the more intelligent noise reduction occurs early in rendering.

Tone Mapping

Tone mapping is disabled by default in order to insure a continuity in the colorimetric and the rendering between the real-time OpenGL engine in Patchwork 3D Design and the Iray raytracer.

Exposure: compensation for the exposure of light in the scene

Burn highlights

Crush shadows

Saturation

White balance: can be set via a choice of standard values, a personalized Kelvin value, or with the color chooser

Photographic tone mapping: replaces the exposure value with photographic exposure settings. These settings include the Cm² factor, the sensor sensitivity ISO, the F-number of the aperture, and the shutter speed.

The reset button restores the default tone mapping settings.

Camera effects

These camera effects are specific to Iray and are fully independent with respect to their equivalents in Patchwork 3D Design.

Bloom: when enabled, the radius, threshold, and brightness scale can be set

Vignetting: provide a value and press Enter. Increasing the value increases the effect.

Materials

Surfaces as light sources

It is possible to use a surface as a light source by selecting a material to be used as a source and assigning that material to the surface.

All of the standard and multi-layer materials in the Matter material library can be selected as light sources. This selection is made from the Iray settings editor.

Materials are selected simultaneously in the Iray settings editor and in the Matter library; you can therefore select the material in whichever interface is more convenient.

Override Patchwork 3D material

Certain material settings can be overridden by Iray-specific settings. The available settings vary with the type of material.

To enable the override settings in Iray, click the Materials tab from the Iray settings editor and select among the following parameters:

• Any Patchwork 3D Design material can be used by Iray as a matte material.
• Iray accepts an AXF file (with refractive or non-refractive clear coats) or a MDL file imported from the hard drive of your computer.
• You can also override the selected material with other materials from the Material Library of the database.

Lighting

All active lights in Shaper have an effect on the Iray rendering. You can override certain settings of these lights.

In the Iray settings editor, select a light to enable the setting override. When a light source uses Iray's settings instead of Patchwork 3D Design's, a check mark appears in the Iray settings editor next to the name of the light.

You can override:

• The intensity
• The use of intensity as radiant existence

For spot type lights, it is also possible to modify the exponent.

For area lights in the form of rectangles and cylinders, the option use as portal light is available. A portal designates a zone, defined in this case by the surface, that allows exterior light to reach and enclosed area. This option produces an effect only when the caustic sampler optimization is enabled.

Snapshot layers

The Iray engine is available for image, video, VR object and VR panorama snapshots. In the corresponding Snapshot editor, select Iray as the render engine.

When the snapshot will be saved in a format that supports layers (PSD), Iray can split the image into different layers.

Render direct and indirect contribution separately: renders separate layers for the direct illumination (light sources) and indirect illumination (global illumination).

Available layers:

• Diffuse layer
• Specular layer
• Glossy layer
• Emission layer
• Alpha layer
• Depth layer
• Normal layer

The calculation of layers does not include transmission.

Sun and Sky

Iray offers a simulation of the light of the sun and the sky.

When the Sun and sky option is enabled, a sun type illumination is added, an infinite plane is used as the ground, and an environment representing the sky is displayed.

The Multiplication value adjusts the environment's luminosity.

The sun settings include:

• The solar disk intensity
• The solar disk scale
• The glow intensity
• The sun's position, which can be set in the Position of the Real-time sun editor

The sky settings include:

• The night color
• The haze level
• The red- or blueshift. Positive values will produce a redshift, while negative values produce a blueshift.

The ground settings include:

• The ground color
• The horizon height
• The horizon blur

Choice of graphics card

Iray can use multiple graphics cards at a time.

All cards available on the machine being used are listed.

Iray can also use CPU threads. This option is disabled by default to prevent Iray from monopolizing the computer's processing power. This is an option provided by Iray that was designed to be used only on a machine used as a rendering server.

Hardware

You can use a machine on your network or an Nvidia VCA to process rendering remotely.

Set up a remote rendering server by clicking on the button in the Iray settings editor.

A check mark indicates an active connection.

Remember to disconnect at the end of a session: in certain cases, including the use of VCAs, other users cannot access the remote service while you are connected.

If a connection is underway when Patchwork 3D Design is closed, the connection will be automatically disconnected.

Iray server

The Iray server is any machine on your network on which the software Nvidia Iray Server is installed. You will need the IP address and the connection port for the server. You will also be asked to provide the ID and password.

A button is added to the snapshot editors: Add to queue. This sends a deferred render request to the Iray server. You will then need to manually run the rendering of the queue on the server. This can be done after the Patchwork 3D Design session has been closed and does not require either Patchwork 3D Design or access to the original computer that requested the render.

It is not possible to encode a video from the Iray server render queue. When a render request for a video is made, each frame will be rendered separately and the output will be made available as an archive file containing all frames.

VCA

A VCA is a calculation device for network use for graphic purposes, notably for use with Iray. VCAs offer a multiplication of the strength of Nvidia GPUs. You must have access to a VCA. An ID and password will be requested.