You want a shadow, but you don't want the object casting the shadow to be visible. This is used for compositing your scene later or incorporating elements into existing footage.
This is actually very easy to do with CINEMA 4D.
Step 1: For the purposes of this tutorial you'll use a Sphere Object and a Floor Object. First, create a Sphere (Objects=>Primitive=>Sphere).
Step 2: Next, create a Floor Object (Objects=>Scene=>Floor). You'll have to position the Sphere on top of the Floor. Select the Sphere Object and move it up. In the Coordinates Manager, enter 100m for the Y Position.
Step 3: Now create a Light (Objects=>Scene=>Light). Double click the Light icon in the Object Manager to change the settings. Be sure Soft Shadows are activated under the General tab and click OK.
Step 4: Move the Light above and to one side of the Sphere. Your scene should now look similar to the image shown.
Step 5: Finally, you will create a Render Tag to prevent the Sphere Object from being seen by the camera, however, it will still cast shadows.
With the Sphere Object selected, create a Render Tag. In the Object Manager go to File=>New Tag=>Render Tag. When the dialog box opens, uncheck the box for Seen by Camera. Be sure the box for Cast Shadows is still checked and click OK.
Step 6: Your object will now cast shadows but it will not be visible.
