IRay


Iray is an interactive path-tracing for photo realistic rendering. When using an Nvidia Graphics card, it is GPU accelerated. GPU acceleration is not used with cards from other vendors, meaning IRay switches to slower CPU rendering in those cases.

To use Iray on Mac OS X, make sure you install the latest NVidia drivers if your card is NVidia:

http://www.nvidia.com/object/macosx-cuda-7.0.64-driver.html

http://www.nvidia.com/download/driverResults.aspx/87193/en-us


You can switch to IRay by going to the renderer menu in the 3D view.


Environment

Lets you access some environment settings by clicking the Edit... option:

As shown in the following image, Iray mode gets more options compared to OpenGL mode.

All these options are available in Iray mode.

The options highlighted in pink, are the only ones available for OpenGL:

OpenGL/Iray shared parameters

Is Visible

Enable/Disable the Environment map visibility in the 3D viewport.


Exposure


Defines the exposure 


Rotation

Defines the (horizontal) rotation for the environment map (also accessible via ctrl+shift+right click shortcut)


Iray parameters

Dome type

Define the shape of the dome:

Sphere Infinite sphere: The environment map is projected on a sphere. You can define the radius of the sphere, while an infinite sphere is virtually always around the scene.


Ground and Sphere with ground: the bottom of the sphere is flattened to simulate a ground. like the previous modes, ground is virtually always around the scene, while you can set the radius of Sphere with ground.


Box with ground: the environment map is projected on a cube. You set the width and height of the cube.


Dome settings

When possible, let's the user set the size of the dome:

Radius: works with Sphere and Sphere with Ground

Width, height and depth: works with Box with ground


Ground

Activate/deactivate  the ground. In practice, the ground is used to receive the shadow generated by the object, helping giving more credibility to you render:

Position:

Defines the position of the ground. Most of the time, you will only use the second slider to tweak the position on the vertical axis, in order to make sure the ground fits with the base of your object.


Reflectivity/glossiness:

Defines the way the ground is supposed to reflect the light.

The reflectivity not only defines the amount of light that is reflected, but also if the reflected light is tinted by the ground once reflected.

Let's some reflectivity examples (with glossiness at 0.5)



The glossiness defines how the amount of light is reflected: the lower the value, and the more scattered the reflected rays are, and the higher the value, the more the reflection will look like a mirror.

Let's check this with a pure white reflectivity value:

Remember that between the 2 examples above, the amount of reflected light is the same: it's just the way they are reflected which is different. Life is awesome!


Shadow intensity

Defines the intensity of the shadow (1 by default).

Decreasing this value will make the shadow less visible


Texture scale

(Works with Sphere with ground) defines the scale of the environment texture at the ground level.


The Edit button is only available in Iray mode and gives access to the following options:

Min Samples: defines the minimum amount of projected ray samples


Max Samples: defines the maximum amount of samples. Iray will try to reach this number with the defined max time (the next parameter), and will stop the rendering process if it manages to reach it.


Max Time (seconds): defines the maximum time Iray will use for the rendering process. The rendering will be stopped when the time is reached, even if the Max Samples is not reached.

Caustic effects: enable/disable caustics in the rendering process.

Note that caustic effects are caused by refraction of the light through an object: if your asset is fully opaque, you can leave this parameter to False, as it will slow down the processing time for nothing.

Take a look at the rendering time: it has been doubled just by activating caustics: use this feature when needed 


Firefly Filter Enabled

When enabled, removes/diminish the presence of some unwanted dots called "Fireflies in the rendering process:

Setting up IRay for material previews with displacement

When you want to create a nice preview of your material  for portfolio purpose or to upload on Substance Share, IRay provides a quick way to add displacement to your preview mesh.

With IRay activated, go to Scene>Edit.

This will display all the objects in your scene. You can activate Subdivision on a per object basis if you object is not subdivided enough.

Choose Length, the default value of 0.1 should give you plenty of precision.


If you still don't see displacement on your mesh, it's because the Height Scale is set to 0 in your materiel settings.

Go to the Materials settings in the 3D View and choose Edit to see the properties and increase the Height Scale.

Here is the result!