The Shadow CatcherThe Shadow Catcher can be used to create shadows cast by objects onto the surrounding background imagery. The shadows cast are not limited to simply a ground plane but can be cast onto other surfaces of varying shapes. option creates shadows cast by objects onto the surrounding geometry. The shadows cast are not limited to a ground plane, but can cast onto other surfaces of varying shapes.
In the Octane Render Target Actor window, activate Alpha ChannelA greyscale image used to determine which areas of a texture map are opaque and which areas are transparent. and disable Keep Environment. When the image renders, the shadows appear over the surface's transparent parts. You can use this image in a compositing package to merge the object and the shadows into the composition.
Figure 1 : Shadows appear in the transparent parts of the image where the Shadow Catcher objects were placed
Shadow catching is accomplished by using the Shadow Catcher MaterialThe representation of the surface or volume properties of an object. (Figure 2). You can also enable Shadow Catcher by activating the Shadow Catcher option on the DiffuseAmount of diffusion, or the reflection of light photons at different angles from an uneven or granular surface. Used for dull, non-reflecting materials or mesh emitters. material (Figure 3), then applying the Diffuse materialUsed for dull, non-reflecting materials or mesh emitters. to the objects receiving the shadow.
Figure 2: Using the Shadow Catcher material to catch shadows cast on a scene actor
Figure 3: Activating the Shadow Catcher parameter in a Diffuse material
When using the Shadow Catcher, make sure there is a light source in the scene. This can be a direct light source, or an Emission map connected to a scene object. Place a Diffuse material on the shadow-catching objects in the scene, and enable the Shadow Catcher option at the bottom of the Diffuse material's parameters. In the Kernel settings, activate Alpha Channel and make sure Keep Environment is disabled.