This page gives some basic details about the Reflect IOR Render Element and how it is used.
||Render Settings window|| > Render Elements tab > Reflect IOR
The parameters for this render element appear in the Attribute Editor under Extra V-Ray Attributes.
Enabled – Enables the render element inside the V-Ray Frame Buffer.
Deep Output – Specifies whether to include this render element in deep images.
Filename suffix – The text added to the end of the rendered file, when saved as a separate file (e.g. myrender.reflIOR.vrimg).
Invert value – Instead of representing pixel values as the IOR value, enabling this option represents values as 1/<IOR>. For example, an IOR value of 1.6 would be represented in the render element as 1/1.6 or 0.625. This option can be used when saving the information in an 8-bit per channel texture, which can be inverted back to the original values later on if desired. This option can be useful when the render element will be imported into an application that doesn't support HDR or EXR files. See the Invert Value example below for more information.
This example shows how the Invert value option can be used to push all colors in the Reflect IOR render element into the 0.0-1.0 range, and also how to determine the IOR values right within the V-Ray Frame Buffer. In each image, the values are sampled using the Show Pixel Information option in the VFB.
Invert value = disabled. All white values are above 1.0.