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:




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.



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 the sky object using the same method as the plane. Click and hold the sky tab and select the sky object.



Next we will create two materials. One for the background which will set the theme of the render and the other will be the shadow catcher. In the Materials Manager, click the Corona tab and then select a "New Material". 



To change it's colour, double click the material thumbnail, click the diffuse tab and using the sliders choose your desired colour and close the window. 



Now we can assign the newly created material to the sky object. To do this, simply drag and drop it onto the sky object either directly in the view port:




...or to the attributes hierarchy.

 


Next we will create the Shadow Catcher Material as we did in the previous step. From the Corona tab in the material manager select the Shadow Catcher Material and assign it to the plane object. 



To set up the Shadow catcher material double click the thumbnail and change the mode from Backplate to Environment. In the environment slot, drag in the sky object and close the material editor. 



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: