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title: "Corona Shadow Catcher Material"
canonical: "https://documentation.chaos.com/space/CRMAX/124625817/Corona%20Shadow%20Catcher%20Material"
format: markdown
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This page provides information on the Corona Shadow Catcher Material, its settings and usage. Overview The Shadow Catcher Material allows you to composite 3D geometry onto a background image (a.k.a. plate) whilst preserving the shadows and reflections (if turned on). Also, you can create an infinite background for your product visualization images.   Settings Matte/Shadow Enviro/Backplate  – The backplate for compositing - a real-world photo. Projection mode  – How to handle projection for secondary (reflected) rays that hit the material. This generally needs to be set to correspond with the backplate projection (simple backplate or 360° enviro map) to get correct reflections of the shadow catcher on the scene object. Alpha mode  – How the shadow catcher is displayed in the alpha channel. Using the  For compositing  option also makes the shadow catcher black for direct rays, which is required for a correct workflow. When Alpha Mode is set to  For compositing , directly visible color of Shadow catcher material is overridden to black. To compose the render correctly, make sure to override directly visible environment color to black as well. Shadow amount  – How much light is bounced off the shadow catcher onto other objects (a relative value). Increasing the value forces less light bouncing, therefore making shadows darker. Reflection Properties Level  – Defines how strong the reflection is. Color  – Allows choosing the color of the reflection. Use matte projection mode  – When enabled, all maps use the camera projection specified by  Projection mode  above. When disabled, only the Enviro/Backplate slot uses it and others are not projected. Fresnel IOR  – Index of refraction (IOR) for Fresnel reflections - controls the amount of material reflection in a physically plausible way. Higher values create stronger reflection. Set this to 999 to disable the fresnel effect (i.e. to create a mirror-like material). Glossiness   – C ontrols how sharp or blurred the reflection is. A value of 1 gives completely sharp reflections, while a value of 0 gives completely blurred reflections. Bump  – Defines the bump level. Project Backplate Option Use enviro for off-screen rays  – Use scene environment for off-view rays when using simple backplate. Off-screen color  – Use this map for off-view rays when using simple backplate.