The ZDepth Render Element is a grayscale image that renders each pixel based on its distance from the camera in the view.
UI Path: ||Toolbar|| > V-Ray Menu icon > Render > VRayRenderElement > Type: ZDepth
Use depth from the camera – Specifies whether to use to camera clip boundaries as the minimum and maximum ZDepth distance. Enabling this option disables the Depth Black and Depth White parameters.
Depth Black – Objects further than this distance from the camera will render as black. This option is available only when Use depth from the camera is disabled.
Depth White – Objects up to this distance from the camera will render as white. This option is available only when Use depth from the camera is disabled.
Depth Clamp – Clamps the ZDepth colors to a linear 0-1 range.
Filtering – Applies the image filter to this channel. Image filter settings are in the Image Sampler tab in the VRayRenderer properties.
The Z-Depth Render Element parameters for minimum and maximum depth, Depth Black and Depth White, can be set to various values to provide different ranges of depth in the render element. In these examples, Depth Clamp is enabled.
The Z-Depth Render Element is useful for adding depth of field to the final image in post production within a compositing application without the need for re-rendering. It can also be used to create basic fog by overlaying it on the composite in Add mode or Screen mode, with color correction as needed.
Note: In the example below the depth of field effect has been exagerated for the purposes of clarity.