How to create an infinite background with the Shadow Catcher Material?



What is the Shadow Catcher Material?


The Shadow Catcher Material allows you to composite 3D geometry onto a background image (or plate) whilst preserving the shadows and reflections (if turned on).

It can be useful for compositing a car onto a road for example:


Link to car model by Fabio Palvelli


Example:


In the following example, we'll show you just how easy it is to set up an infinite background with Corona Renderer using the Shadow Catcher Material


***Link to scene*** Note: The scene below has been rearranged for the purpose of this tutorial.


Setting up the scene


So to start we will add our plane object to act as our floor. To do this, simply click and hold the cube primitive tab and select a plane object.



Now we can add a Corona Sky object to the scene. Click on Corona > Corona Sky.



Change the "Type" from "Physical sky" to "Simple color" and then choose your desired color.



Now let's create a Corona Shadow Catcher Material from the material editor and apply that to our plane object. 



Double-click the Shadow Catcher Material to change its mode from "Backplate" to "Environment" and then drag in the Corona Sky object into the "Environment slot".



With the Shadow Catcher scene almost complete, It's time to add some additional elements. In this example a Corona Area Light was placed above the subject and Reflection was activated in the Shadow Catcher Material. To activate reflections, double click the Shadow Catcher Material and make sure the Reflection check box is ticked. Adjust the reflections to your liking and enjoy your infinite scene!



Final render: