One more object we haven't discussed yet that is essential for any Unity application is the Camera. Unity developers may often add a Main Camera to their project scene and not give it much more thought. But in AR, the camera is especially important.
Cameras are devices that capture and display the virtual world for the player. For rendering computer graphics, the camera's Pose (position and rotation transform), its rectangular Viewport and Field of View (FOV) together define how much of the scene is visible and rendered on the screen. The camera Pose is where the camera is pointing. The Viewport is like a rectangular window that we're looking through; anything outside the Viewport is clipped and not drawn. The Field of View defines the viewing angle. In regular video games, developers enjoy the option to modify any of these options to give the cinematic camera effects they want to emulate on the screen.
But for augmented reality, the constraints on these parameters are...