Apple Motion 3 - Manual (Page 749)

Chapter 8 Working with Particles 749
2 If your project does not contain a camera, click the New Camera button in the Toolbar.
If your project is a 2D project, a dialog appears asking if you want to switch your 2D
groups to 3D.
3 Click Switch to 3D.
A camera is added to the project, and your layers are turned into 3D layers.
4 In the 3D View tools (in the upper-right corner of the Canvas), drag the Orbit tool (the
center tool).
As the camera rotates, you can see that the particles are emitted in Z space.
Pan tool
Orbit tool
Dolly tool