You can change the appearance and function of your shot by where you place the camera. Your camera angles come from the positions you choose for the camera and which way it is aimed.
If you are rendering a scene from several different camera angles and plan to edit the different shots together into a seamless sequence, then it is vital that you make all of your camera angles come from camera positions on the same side of a line of action. A line of action is the path along which your subjects are looking or traveling, or an imaginary line between two characters who are interacting. For example, in Figure 7.4, the line of action is shown by the yellow line between the two characters.
Figure 7.4. To maintain screen direction, all camera shots are taken from the same side of an invisible line of action.
You would not want to cut to any angle on the characters filmed from the other side, because that would reverse the direction that the characters appeared to be facing, and could confuse the audience. For example, if a character had been facing toward the right side of the screen, you should not choose a camera angle that suddenly makes her appear to be facing to the left in the next shot, because she will appear to have turned around.
Imagine a character who is traveling or in a chase. If he is running toward the right side of the screen in one shot, then he should continue to appear running toward the right side of the screen in every shot. Unless the character actually turns around, no change of camera angles should be used that would reverse his screen direction.
Football fans are familiar with this concept from the way football games are televised: All of the cameras are normally put on the same side of the stadium. On occasion, a camera will be used on the opposite side, to capture action that would not have been visible otherwise. To avoid confusion, whenever they cut to the camera from the opposite side of the line of action, the words "Reverse Angle" are superimposed on the screen.
Perspective is the point of view or position you choose for your camera. Whenever the camera is in a different position, it shows the scene from a different perspective.
Figure 7.5 shows three different perspectives of a person standing in front of a bridge. To maintain a close-up of a similar size from each perspective, a telephoto lens was used when the camera was farther away (left), a normal 60mm lens at 3 meters from the subject (middle), and a wide-angle lens with the camera was close to the subject (right). Although you can notice barrel distortion in the shot taken with the wide-angle lens, the lenses themselves do not change the perspectivethey only magnify the scene to make comparison possible on similar size shots.
Figure 7.5. A shot from a distant perspective (left) compresses space; a shot from 3 meters away appears more normal (center); and a shot from a close-up perspective tends to expand space and distort features (right).
Notice how the bridge appears to be looming right behind the woman in the left image, but on the right, from a closer perspective, the bridge seems much farther away, and we see more of it. Figure 7.6 shows a similar comparison in 3D. The left image was rendered with the camera far away from the scene, but with a 2-degree angle of view. On the right, the camera has been positioned close to the chess pieces, but given a 120-degree angle of view.
Moving the camera far away from the subject seems to compress or flatten space. This effect could be useful if you wanted to make a character appear lost in a crowd, to make a space seem cramped, or to make objects appear closely stacked together. If you zoom in on a subject from a distant perspective, you will see a much smaller slice of the background behind the subject, which could be useful if there were something in the background you wanted to accentuate.
Figure 7.6. Perspective in 3D works just the same as perspective with a real camera: Spaces seem compressed from a distant perspective (left) and expanded from a close-up perspective (right).
Moving the camera close to the subject distorts distance. It can even make a character's facial features appear to stick out farther, such as exaggerating the size of a person's nose. Most photographers back off by about 3 or 4 meters when trying to take a flattering portrait, instead of sticking the camera right in the subject's face. However, you don't want to back off too far, because even though you could compensate for extreme distance with a telephoto lens, doing so would tend to flatten a person's face so that horizontal features such as ears appear to stick out.
When the camera is moved near your characters, and you zoom out to cover the action from the close perspective, there will be a broader view of the background behind the character. Seeing more of the environment around a character could be desirable, but sometimes it requires you to build a more complete set or add more trees to your scene in order to fill up the visible area.
Rendering with the camera near a character can also make any action appear to move more quickly or cover a greater distance. This is especially true for motion directed toward or away from the camera. Getting the camera right into the middle of the action can make animation appear more dynamic, and also puts the audience closer to the perspective of the characters.
Animating a camera's position and field of view at once, in opposite directions, can produce a disturbing effect. For example, if the shots shown in Figure 7.6 had been frames in an animation, simultaneously moving the camera toward the subject while zooming out to compensate, the perspective would shift oddly during the shot. This effect has been used in horror movies to make a hallway appear to grow longer in front of a character as he struggles to run down it.
If you want to choose a natural-looking perspective, a good rule of thumb is to think about where a person might be standing within the 3D space to watch your scene, and position the camera at the same distance. For example, if a scene takes place indoors, the camera should not be much farther back than the size that an actual room would naturally allow.
It is important to note that your perspective on a scene changes only when the camera is moved to a new position. Perspective is not changed by the camera's zoom or field of view. When the camera is left in the same position, the perspective will be the same, no matter how telephoto or wide-angle your lens. Choosing a longer focal length for your camera in 3D graphics gives you just the same perspective as if you had rendered with a short focal length and then cropped the image down to the close-up you wanted.
The most normal-looking shots will be the ones taken with the camera at eye level. Moving the camera to different heights can create other camera angles that are sometimes more interesting or dramatically useful.
A low-angle shot, with the camera positioned below your character, looking up at her, can serve to make a character look bigger, stronger, more honest, or more noble. Low-angle shots can also exaggerate the size of environments and architectural spaces.
A high-angle shot, with the camera aimed downward from a position above the character, can make a character look sly, small, young, weak, confused, cute, or childlike. Figure 7.7 shows how a character looks from a low angle (left) and a high angle (right.)
Figure 7.7. A character will be perceived differently from a high angle (left) than a low angle (right). Images by Andrew Hickinbottom, www.andrewhickinbottom.co.uk.
If you want to animate more realistic and natural camera moves, it helps to study the most popular types of moves used with a real camera:
Figure 7.8. A rack focus directs the audience's attention by changing the focus during the shot.
Note that many of these common types of camera moves do not involve actually changing the camera's position. When the camera pans, tilts, zooms, or rack focuses, it can remain mounted in the same place on a tripodyou only aim the camera in a different direction or adjust the lens.
You don't need to animate the position of the camera if alternatives such as panning to follow your animation, or simply cutting to a new shot, will do just as well. An unmotivated camera move could distract the audience instead of helping you tell the story.
An old attitude towards animating the camera in 3D was that you needed to carefully imitate the types of real dollies and cranes on which a movie camera was traditionally moved. 3D artists used to be afraid that if they used any physically impossible camera moves, their animation would seem unrealistic. However, in recent years, filmmakers have begun to use 3D graphics, motion-control camera rigs, digital compositing, and other technologies to create seemingly impossible camera moves in live-action films.
The widespread use of 3D graphics to previsualize motion pictures has further encouraged live-action directors to plan their movies using all kinds of camera motion that in the past would have been seen only in 3D animation or video games. Audiences are growing accustomed to seeing the camera fly through scenes in ways that would have seemed remarkable in previous decades.
Of course, you still need to make sure that any camera motion helps in telling your story instead of distracting from it. Learn to imitate and use old, conventional camera moves when they meet your needs. But, if it fits your story for the camera to fly through a keyhole or follow action out the window of a moving car, go ahead and animate the camera whichever way best fits your scene.
In editing, cutting between two moving camera shots can be particularly distracting. Even if the camera motion within each of the shots looked natural, editing between a camera moving in one direction and a camera moving in a different direction can be jarring in the cut. When animating any camera move, it is a good idea to begin with a well-composed static shot before easing into the move. Upon completing the move, the camera should come to rest at another well-composed static shot.
For natural-looking camera moves, think of the role of a camera operator watching a scene. Often, something needs to begin to happen, such as an actor starting to move, before the camera operator reacts to it and moves the camera to follow the action. Camera motion looks most natural if it begins just after the motion it is intended to follow, as if the operator needed a fraction of a second to react to the motion. Also, when a camera pan comes to an end, it can slightly overshoot its mark and then slightly correct backwards a fraction of a second later, as a human operator often tends to do aiming a handheld camera.