Deep image rendering stores the Z-depth location of an object with samples of a rendered image. It works best in scenarios where traditional compositing techniques fail. Such as compositions where masking out overlapping objects is too difficult, or scenes that render images images using depth-of-field or motion blur, or compositing footage in rendered volumes.
Most major compositing applications now support deep image compositing. The disadvantage of deep image rendering is the large amounts of memory required to render and store deep images.
The standard output format is OpenEXR.
Enabling Deep Image Rendering
Deep image rendering is enabled via the Kernel tab in the Render Settings window. Deep Image Rendering is only supported with the Path Tracing and Direct Lighting kernels. Deep image can be enabled by checking the Deep Image check box as shown in figure 1.
Figure 1: The Deep image check box in the OctaneRender Settings tab of the Render Settings window.
For a typical scene, thousands of samples per pixel will be rendered by the GPU, however, there is only a limited amount of VRAM. It is therefore necessary to be able to manage the number of samples stored. Two parameters are provided for this purpose:
- Max. depth samples specifies an upper limit for the number of deep samples we can store per pixel.
- Depth tolerance specifies a merge tolerance, i.e. when 2 samples have a (relative) depth difference within the depth tolerance they are merged together.