You can use 3D in After Effects without setting a camera—just toggle a layer to 3D and voila—but it's a little bit like driving a race track using a car with an automatic transmission: You can't maneuver properly, and before long you'll probably crash.

Furthermore, when you set a camera, you encounter one of the more helpful and visually descriptive portions of the After Effects user interface: the Camera Settings dialog (Figure 9.1). If you know how to interpret what it is showing you, the dialog's diagram tells you virtually everything you need to know about how the After Effects camera sees the 3D world.

Figure 9.1. Visual artists love visual user interfaces, and the Camera Settings dialog is one of the few to include a diagram. That's a good thing because it also contains a lot of settings that most users find a bit abstract. Here are the default settings for a 50 mm preset, which happens to be the setting that introduces no change of lens angle from a flat 2D view.

Virtually everything is an apt description, moreover, because one thing that is confusing about After Effects' camera is its use of lens settings from still SLR (single lens reflex) cameras to describe how long or wide a lens is. The diagram in Camera Settings, however, is helpful not only in making some sense of the numbers involved, but also in learning how cameras—be they real or virtual—operate.

Lens Settings

The default camera in After Effects uses the 50 mm preset (listed in the Preset pull-down menu in the Camera Settings dialog). Switching all of your layers to 3D and setting this camera does not change the appearance of your scene whatsoever, which is significant. Like many added features in After Effects, it is specifically designed not to fundamentally change (or corrupt) the appearance of your work when you switch it on.

But hold on—there's no such thing as a 50 mm virtual camera lens because virtual space doesn't contain millimeters anymore than it contains kilograms, parsecs, or bunny rabbits. The virtual world is generally measured relative to pixels. Everything else is just kind of made up until you find its analogue in the real world. So where did the name come from?

On any physical camera, there is a lens length that would be considered neither long nor wide. This lens captures a scene without the shifts in perspective and distortion of features—not all of them displeasing, mind you—associated with lenses that tend more toward the fisheye or telephoto perspective (Figures 9.2 through 9.4).

Figure 9.2. The extreme wide or fisheye lens pointed inside an evenly proportioned 3D box. Note that the “long” look of the box is created by this “wide” lens, which tends to create very strange proportions at this extreme. A physical lens with anything like this angle would include extremely distorted lens curvature.

Figure 9.3. A telephoto lens (using the 200 mm setting) pushes items together in depth space, shortening the distance between the front and back of the box dramatically.

Figure 9.4. The default lens (50 mm setting). If the Z Position value is the exact inverse of the Zoom value, and all other settings are at the default, this is the view you get, and it matches the appearance of setting no After Effects camera whatsoever.

On a 35 mm SLR still camera such as has been used for professional photography for decades, 50 mm is the median lens length and the namesake for the After Effects preset. SLR cameras are familiar to many more people (including After Effects developers) than professional film or video cameras. But how many movies have been shot predominantly using an SLR camera? Not many; in fact, only one candidate comes immediately to mind, La Jetée, the 1962 Chris Marker film that was the inspiration for Terry Gilliam's movie 12 Monkeys.

Your source more likely would be from a 35 mm motion picture camera shooting Academy ratio, on which, it just so happens, a 35 mm lens is considered flat or normal. But if your footage would come from a miniDV camera, the tiny CCD requires an equally tiny default lens length of around 4 millimeters. The appearance of different lens lengths is directly related to the size of the backplate or video pickup, the area where the image is projected inside the camera. The smaller the film size (or CCD size), the shorter the default lens.

The point is that millimeters don't mean much without a physical lens and a physical camera. The only setting in the Camera Settings that truly, universally applies, whether images were shot in IMAX or HDV or created in a 3D animation package, is the Angle of View.

Real-World Camera Settings

So how exactly do the After Effects camera's settings line up with those of a camera in the physical world? If you know a camera's settings, how do you use them?

First, look again at the diagram provided in the Camera Settings dialog. Four interrelated numerical fields—Film Size, Focal Length, Zoom, and Angle of View—are oriented around two triangles sharing a common hypotenuse (Figure 9.1). On a physical camera with a prime lens, these values would all be fixed. With a zoom lens, the Film Size would be fixed (as it always is in a physical camera), but the Zoom and Focal Length could be changed, resulting in a change in the Angle of View. These four settings, then, are interrelated, as the diagram implies.

Note

Yes, there is an optional, indirectly related, fifth numerical field in the Camera Settings diagram: Focus Distance, which you enable by checking the Enable Depth of Field toggle. This is more like a camera's aperture setting; I'll touch on it separately later.

And so it is with the After Effects camera: Change Angle of View, Zoom, or Focal Length and the other two values among those will change correspondingly, but Film Size will remain fixed. Film Size is useful only if you're trying to emulate a specific camera, which I'll get to in a moment.

Lengthen the lens, and Focal Length increases as Angle of View decreases. A physical telephoto lens really is longer from lens to back plate, and adjusting its zoom does make the lens longer or shorter. The only feature that would make this diagram any clearer is if it actually articulated to visually display the difference in Angle of View as clearly as it can be seen (particularly in the top views) in Figures 9.2 through 9.4.

Making Your Adjustments

The only two settings to focus on (no pun intended) are Zoom (for animation) and Angle of View (to match source where that measurement is available). Film Size and Focal Length, measured in pixels, make sense only relative to those two. Angle of View is the actual radius, in degrees, that the camera sees. The setting corresponds directly to real world cameras, and Angle of View is a setting you will see in other computer graphics programs, so you can match it precisely if you need to.

The Zoom value is the distance of the camera lens, in pixels, from the plane of focus of its subject. By default when you set a new camera, After Effects always sets that camera's Z Position value equivalent to the negative of its Zoom value, so that everything that is at the default Z position of 0.0 remains framed the same as it was before the camera was activated. The plane of focus represents an area the size of the composition (Figure 9.5), so wherever it is relative to the camera is the point where all items will be framed by that area exactly.

Figure 9.5. You can easily have overlooked the highlighted settings in the Camera Settings dialog. Comp Size (on the right) shows the horizontal size of the composition, in pixels, if the Units and Measure Film Size settings are as shown. This makes the relationship between Zoom and Plane of Focus clearer, although Comp Size is showing a horizontal measurement while the diagram makes it appear vertical.

There are several cases in which having the Zoom value in pixels is ideal. It helps for reference when creating depth of field effects, and it makes it easy to tie the position of the camera and the zoom together via expressions for depth of field and related effects (discussed later).

And how do you put all of this knowledge to work? You probably have one of two goals: Either you're matching settings that came from a real camera in order to match your elements to images taken with that camera, or you're creating a shot from scratch but want it to look like it was shot with a particular camera and lens. Here are some of the things you have to consider:

One specific piece of information that can help you match existing footage is a camera report, a record of the settings used when the footage was taken. If the crew was large enough to include an assistant cameraman, this information was taken down and can be made available.

Lens Distortion

If a virtual camera is set with a wide lens angle, the software simply samples a wider (and taller) area of the scene, as you saw in Figure 9.2. This dramatically changes the perspective of 3D space, but it does not actually distort objects the way a real camera lens does because it relies on no lens whatsoever. All the software is doing is widening the view area and scanning, in a linear fashion, each pixel that falls in that area.

A real camera cannot simply widen its view area, which is essentially fixed. It can only “see” what is perpendicular to the surface of the lens glass, so it uses a more convex lens combined with a short lens length to pull a more disparate (wider) range of view.

At the extremes, this causes lens distortion that is easily visible; items in the scene known to contain straight lines don't appear straight at all, but bent in a curve (Figure 9.7). In a shot taken with a fisheye lens, it's as if the screen has been inflated like a balloon. It's rare, but not unprecedented, for a shot in a movie to look like this (but there are always exceptions, for example the point of view of a droid in a certain big-budget science fiction film).

Figure 9.7. The somewhat psychedelic look of lens distortion at its most extreme. The lens aberration in this case is so extreme that even the flare caused by the front lens element is extremely aberrated. You could easily set an equivalently wide lens with the After Effects 3D camera, but none of the curving of what should be straight lines (the ground plane, the building outline) would occur.

As you work with more and more footage, particularly at film resolution (where the phenomenon is often more apparent), you start to notice that many shots that don't seem so extreme as a fisheye perspective have some degree of lens distortion. Even if you can't spot any curved edges that should appear straight at the edge of frame, you might notice that motion tracks from one side of the frame don't seem to apply equally well at the other side of the frame, proportions go out of whack, and things don't quite line up as they should (Figure 9.8).

Figure 9.8. The curvature of items that you expect to be straight is one clear clue that there is lens distortion in this scene, but the surest sign is that an attempt to corner pin a yellow solid to the side of the building fails; it is not possible to make all four corners and edges line up properly.

There's no way to introduce lens distortion directly to a 3D camera, but the Optics Compensation effect (Professional version only) is designed to add or remove it in 2D. Figure 9.9 shows this effect in action. Increasing the Field of View makes the affected layer more fisheyed in appearance; to correct a shot coming in with lens distortion, check Reverse Lens Distortion and raise the Field of View (FOV) value.

Figure 9.9. The process of removing distortion must take place in a composition larger than the source, padded to allow what happens to the corners of the image. The Beam effect is used on an adjustment layer, below the Optics Compensation effect, to act as a virtual “plumb line” to check the precision of a line near the edge of frame (where lens distortion is strongest).

This process is not exactly scientific, because the Field of View settings don't correspond to measurable phenomena, such as difference in Lens Angle. You have to look for what should be a straight line in the scene and adjust the setting until you're happy with the match. The specific workflow is

1. Having identified that there is lens distortion on a background plate to which you must add foreground elements (as in Figure 9.8), drop the background into a new composition that is at least 20% larger than the plate to accommodate stretching the corners.

2. Add an adjustment layer above the plate layer, and apply Optics Compensation to that layer. Check Reverse Lens Distortion and raise the Field of View (FOV) setting until lines that should appear straight in your image look straight.

3. Add a Beam effect below the Optics Compensation effect. Make its Inside Color and Outside Color settings match (using any color you'll be able to see easily), and align the Starting Point and Ending Point along an apparently straight line near the edge of frame. Fine-tune the Field of View setting a little more until the line is plumb (as in Figure 9.9).

4. Pre-compose all of these layers and set this new composition as a guide layer. In Figure 9.10, you can see that the corner pin is now successful, but you actually want to match the distortion of the source shot.

   

   Figure 9.10. Over the undistorted background plate, you are able to freely position, animate, and composite elements as if everything were normal. Note that the perspective is still that of a very wide angle lens, but without the curvature. Any elements you positioned in 3D space would need to have a similarly wide Angle of View to match this perspective.

5. Create a new master composition containing the background plate and the laid-out foreground element. Copy Optics Compensation from the adjustment layer where you undistorted the background and paste it to the foreground element but turn off Reverse Lens Distortion. You have applied the exact distortion of your background to your foreground elements, and they now match up (Figure 9.11).

   

   Figure 9.11. Back where you started, by applying the same Optics Compensation effect that was used to undistort the background to the foreground layers, but with the Reverse Lens Distortion box now unchecked, the foreground distorts to match the background, and features now line up properly.

You have tricked After Effects into compositing elements into a distorted environment. Stu Maschwitz, who supplied me with the example used for the step-by-step figures, notes that it is important not to undistort and redistort the plate image itself, which will soften it dramatically. He summarizes the process with the following haiku:

• undistort, derive

• reunite distorted things

• with an untouched plate

Using a 3D camera in an effects situation typically entails compositing 3D elements over a 2D plate background. This is no big deal. After Effects does not force you to decide up front whether your composition consists of a 2D or a 3D world, and it can contain both, layered together. This is a huge advantage as long as you're clear about managing the composition properly.

And why is it an advantage to mix layers in this manner? Once you understand it, you have a lot less to worry about:

Everybody wins.

Where are the gotchas of this approach? They are all special cases:

So go ahead, freely mix 2D and 3D layers. Just make sure, if it gets confusing, to double-check the gotchas list and ascertain that you know what you're doing.

Note

You can toggle through the camera animation tools using the C key to orbit, track XY, and track Z in the active view. Remember, however, that you cannot orbit in isometric views (Top, Front, and so on).

You may feel you know all about working with a 3D camera already, but the After Effects version is slightly different from the 3D camera in other applications. For example, the After Effects camera has Transform options that are unique from all other types of layers (Figure 9.14), and a couple of things about them are a little strange to people used to other types of layers in After Effects, or other 3D programs. Take a closer look.

Figure 9.14. The Transform values for the camera include no anchor point and two sets of rotation data: the Orientation of the camera (its basic position), as well as separate X, Y, and Z rotation values. Separating these obviates the need for separate nulls to solve complex 3D rotations. The Point of Interest appears only with the default Orient Towards Point of Interest option (see Figure 9.15).

Note

The Y axis is upside down in After Effects 3D, just as it is in 2D. Long ago, before 3D in After Effects was even a glimmer in David Simons' eye, it was decided that the 0,0 point in After Effects space should be at the upper-left corner of the frame, so that increasing the Y value would move the layer downward on the Y axis. It was left this way when 3D was added for consistency's sake.

Push versus Zoom

Knowledgeable effects artists understand that there is a huge difference between a camera push, in which the camera moves closer to the subject, and a zoom, in which the camera stays in place and the lens lengthens. You must make a conscious decision which type of move you're doing and adhere to the rules.

Figures 9.16a and b demonstrate the difference between pushing and zooming a real camera. Remember that zooming changes the actual lens angle, and has more of an effect on the immediate foreground and faraway background framing than a push.

Figure 9.16a and b. The difference between a push in (9.16a) with a wide angle lens and a zoom (9.16b) from a distance is evident especially by what happens to the perspective of the orange ball in the background. With the zoom, its apparent scale is much greater, and it is much more prominent in shot. It seems to be closer to the foreground figures than in the image that was shot wider, but close-up.

Most of the time, you will animate a push; zooms, generally speaking, had their heyday in the era of Sergio Leone. That's a good thing because it is evidently easier to get away with a 2D push than a 2D zoom due to the static lens angle. The relationship and perspective of objects close up does not change with a push the way it does with a zoom.

Note

The Keyframe Assistant called Exponential Scale (in the Animation menu) is the old-school, pre-3D way to fake the illusion of a push on a 2D layer. As far as I'm concerned, there is no reason to use it, given how limited it is compared with creating your push in true 3D space.

Push it Good

Why use a 3D camera for a simple push when you could instead scale up the contents of a comp in 2D? If you're traveling any significant distance at all, a scale is too linear to achieve the illusion of moving in Z space. Instead, pick up a 3D camera and move that. You can add eases, stops and starts, a little bit of destabilization—whatever works for your shot.

When you perform your 3D push, however, do it on a single pre-composed layer rather than individual coplanar 3D layers, unless you're separating your source layers into planes of varying depth. Why? Because coplanar 3D layers easily lose proper layer order as After Effects calculates their movement in floating point space. There's no reason it should work, and you should avoid even attempting it.

Your camera move will look more natural if you add keyframe eases, giving the impression that there was a real camera operator behind the lens; if you're unclear about how to create an ease, check Chapter 2. You may even want to add a little extra hesitation or irregularity to the default ease curve to give it that feeling of a camera operator's personality (Figure 9.17).

Figure 9.17. You can finesse a simple animation just by highlighting the keyframes and adding Easy Ease (F9 on your keyboard), but why stop there? Lengthening the Bezier handle for the first keyframe gives the camera that added realistic inertia moving from a static position.

But wait—a move in or out of a 2D shot—isn't that going to look wrong because it lacks any kind of parallax? It might, unless it's subtle. If you're dealing with enough of a move that planes of depth should change their relative perspective, 2D objects are probably not going to hold up. This goes doubly for tracking and panning shots, crane-ups, and other more elaborate and dimensional types of camera moves. Unless these moves are very small, you're going to blow the 2.5D gag. If in doubt, try it and ask neutral observers (or your effects supervisor) to tell you if they buy it.

The exceptions to the 2D object limitation are soft, organic shapes, such as clouds, fog, smoke, and the like. With these, you can fool the eye into seeing 3D depth where there is none, and you can get away with staggering them; the parallax even helps sell the shot. (For more on this, see Chapter 13.)

Note

Remember that toggling on Collapse Transformations causes any 3D layers in a subcomposition to look at the camera in the current comp, rather than in the subcomp. If you don't know to expect this, it may baffle you.

Camera projection (or camera mapping) is the process of taking a still photo, projecting it onto 3D objects that match the dimensions and placement of objects in the photo, and then moving the camera—typically only along the Z axis—providing the illusion that the photo is fully dimensional (right up until the camera move reveals some area of the image that wasn't part of the photograph). It has been used for some very elaborate visual effects sequences over the years and is often employed by matter painters as a way to keep 3D modeling simple and to focus efforts instead on painting.

Figures 9.18a, b, and c show a camera projection that Stu Maschwitz set up, ambitiously featuring the shapes of two parked military vehicles. Typical camera projection examples consist of such cube-shaped items as crates and boxes. In this case, a dozen separate planes were created to form a crude 3D model, all white and ready to receive a projected image (Figures 9.19a, b, and c). This example shows both the magic of this technique—deriving perspective shifts from a flat, still image—and the associated problems of image tearing when an area of the frame is revealed that had previously been obscured in the source photo.

Figure 9.18a, b, and c. The progression from the source image (9.18a) through the camera move. By the final frame, image warping and tearing are evident, but the perspective of the image is essentially correct for the new camera position. The tearing occurs simply because as the camera moves it reveals areas of the image that don't exist in the source.

Figure 9.19a, b, and c. The rather complicated setup for this effect: from the top (9.19a) and side (9.19b) views you can see the planes that stand in for the vehicles and orange cone. Once setup is complete, animating the camera is a relatively simple matter (9.19c).

The key to pulling off an effect like this is obviously the setup: How is it that the one “texture” of the image (the photo) sticks to the 3D objects? The fundamental concept is actually relatively simple; getting it right is a question of managing details, and that part is fairly advanced and not for the faint of heart. The steps to projecting any still image into 3D space are as follows:

The number of variables that may come up as you employ this technique with your own images are many, and the result is likely to exhibit the problems shown in the figures, so if this sounds like more trouble than it's worth, it probably is. If, on the other hand, you're feeling daring and ready to try something tricky, take a look at the example file, and feel free to give it a whirl.

If your source footage can easily be divided into planes of depth, you can achieve a rack focus effect that matches the way this effect is achieved in a physical camera. The focal point passes from an object in the foreground to one in the background or vice versa, and the depth of field is narrow enough that only the immediate plane of focus is seen in sharp detail.

With a physical camera, this type of shot requires a narrow depth of field, which is created by lowering the f-stop value. Doing so influences shutter angle and the amount of light passing through the aperture, so the color response and likelihood of motion blur in the shot are affected.

Not so with the After Effects 3D camera, which has Aperture and F-Stop settings as well (Figure 9.20), but they affect only focal depth. The two settings are tied together; changing one in the Camera Settings dialog has an inverse effect on the other and the mathematical relationships are not linear. F-Stop is the setting more commonly referenced by camera operators, and yet only Aperture is available to be adjusted and keyframed in the timeline.

Figure 9.20. By checking Enable Depth of Field in the Camera Settings dialog, you enable the settings associated with it, including Focus Distance (the distance in pixels that is in focus, which can be locked to the Zoom value using the check box just below it), as well as Aperture and F-Stop, which are different methods of controlling the same thing: the relative depth of field. A low F-Stop (or high Aperture) as shown here with a Blur Level of 100% will create a shallow depth of field.

After Effects depth of field settings can be matched to a camera report, provided that you have the camera f-stop setting that was used when the footage was shot. If so, open up the Camera Settings dialog (Ctrl+Shift+Y/Cmd+Shift+Y, or click on the Camera in the Timeline window), check the box labeled Enable Depth of Field, and enter your value for F-Stop.

The key to this effect is to offset at least one layer in Z space so that it is out of focal range. Now you can animate Focus Distance in the timeline; in the Top view, set the Focus Distance (under Options) to match the layer that will be in focus at the beginning of the shot, and keyframe it, then change the Focus Distance to match a second layer later in the shot (Figures 9.21a and b).

Figure 9.21a and b. In the Top view it is easy to animate the Focus Distance, denoted by a red boundary line, to animate from the far plane (9.21a) to the near plane (9.21b).

A static focus pull doesn't look quite right; changing focus on a real camera always alters the zoom slightly. To sell this shot, which starts on a view of the city and racks focus to reveal a sign in the foreground, I add a slight camera pull-back, which takes advantage of the nice shift in planes of motion that I get from my repositioned layers (Figure 9.22).

Figure 9.22. The final shot is a rack focus combined with a gentle pull-back, with eases at the start and end of the Position and Focus Distance animations.

The rack focus method generates camera blur that is realistic as far as moving and changing focus on a camera go, but the After Effects camera is not capable of generating the look of a truly defocused lens because of what happens to out-of-focus points of light that pass through a camera lens and aperture.

Boke is meant to connote the look and feel of how points of light become discs of light (also called circles of confusion) that take on the character of the lens itself, as with lens flares (another effect that is the result of the lens interacting with light, covered in Chapter 12). This would seem to be rather obscure and arcane, except it produces beauty and suspense in a movie.

How so? Shots create suspense by keeping elements out of focus. We may have a notion of what we are seeing, or we may not (Figure 9.23). We remain intrigued as viewers as the shot focuses in from a strange wash of color and light (Figure 9.24).

Figure 9.23. Offered a dollar by Stu if I could guess what this image is, I guessed a beanbag chair. I was wrong. The correct answer is at the end of this section.

Figure 9.24. Even in the very first, most blurred frame of this shot pulling back from the lawn, you have a good idea what you're looking at, yet the appearance is strange and compelling. Note that a few blades of grass in the extreme foreground retain the quality of boke although most of the shot is in focus.

So what, exactly, causes this phenomenon, and how should you think about it? A perfect lens, photographing a point of light that is out of focus, creates a soft, spherical blur to represent that point. What was a bright point is now an equally bright, larger, softer area. If you tried to re-create this effect by simply blurring an image, the blur would have the effect of graying out toward the edges rather than retaining the brightness of the source. This is true not only of blurs that result from defocusing, but of motion blur as well (Figures 9.25a, b, and c).

Figure 9.25a, b, and c. Motion blur generated the standard way (9.25a and b) literally pales in comparison to true motion blur on illuminated elements (9.25c).

Moreover, most camera lenses are not perfect, so you will not see perfect blurred spheres. The digital images in Figure 9.24 show spheres that are brighter toward the edges than in the middle; an anamorphic lens will show squashed spheres, and as with lens flares, the blades of the aperture diaphragm will sometimes be visible in the circles of confusion, making them hexagonal (or pentagonal, and so on, depending on the number of blades in the opening).

Go for Boke

Okay, let's say you're sold on the look of boke blur and want to incorporate its effect into your shots. What can you do in After Effects to recreate it?

In Chapters 11 and 12, guest author Brendan Bolles and I look at ways in which working in true linear color space can help recreate at least one aspect of realistic camera blur—that the hotspots do not dim down as they are blurred, but retain their brightness. True linear color includes overhead for overbright pixels, and so you can build up a boke-like effect by building up (via Add mode) and blurring elements in the scene that should appear brighter than the surrounding scene. The re-lighting tutorial at the end of Chapter 12 includes creation of a sun sphere in just this manner.

There are also third-party solutions out there to help you fake this effect. I don't mean the verb “fake” to connote that you should instead go for the “real” method. This phenomenon occurs only when a blurred or defocused element passes through a physical lens, so if you're recreating this in After Effects, faking it is your only option. The best tool on the market for creating good-looking lens blurs is probably Frischluft's Lenscare (for After Effects and Photoshop). The default settings are not reliable, but if you're willing to make some adjustments and use such optional additions as depth maps (for 3D footage), you can derive some lovely results with this plug-in (www.frischluft.com).

You might not be able to recreate the look of that twenty-dollar bill in Figure 9.23 so easily, but if you pay attention to what happens in these surprising reference images, your camera blur will be that much closer to what you would get out of a real, defocused camera.

Note

If you're interested in learning more about the phenomenon of boke, good information is available on the Web. At www.bokeh.com you will find links to essays and tests exploring camera blur, including an excellent essay from luminouslandscape.com written by Michael Reichmann.

After Effects 6.5 Professional includes a suite of three tools for automated grain sampling, grain reduction, and grain generation: Add Grain, Match Grain, and Remove Grain. Add Grain you adjust entirely manually, but Match Grain and Remove Grain sample a noise source layer to give you an initial result that you can then adjust.

If you've been reading closely up to this point, you know I'm not a fan of using the automated solutions. Not so in this case. The Match Grain effect does not seem to be appreciably slower due to grain sampling than Add Grain, which does not perform any sampling and includes all of the same controls. Therefore, I recommend you see what Match Grain can come up with as a starting point, and then work from there. In either case, the steps are the same:

In most cases, this is all you need to do for a result that will work. You can copy the effect and paste it to any foreground layers that need grain. If the foreground layer already contains noise or grain, you may need to adjust the Compensate for Existing Noise percentage for that layer.

Obviously, I left a lot of other controls alone (Figure 9.29); the Application category, for example, contains controls for how the grain is blended and how it affects shadows, midtones, and highlights individually. Typically these are overkill, as are the Sampling and Animation controls, but how far you go in matching grain before your eye is satisfied is, of course, up to you. This is one more case in which slamming the result can help ascertain its effectiveness (Figure 9.30).

Figure 9.29. Match Grain clearly has a lot of controls, and yet the ones you will use most often are in the highlighted region, mostly under the Tweaking and Color categories. It is best to go top to bottom, first adjusting overall Intensity, Size, and Softness, then refining the individual Channel Intensities and Channel Size (as in Figure 9.28).

Figure 9.30. How good a match? As always, slam the result—with an adjustment layer containing a Levels effect with its Gamma and Output Black raised—and behold. Adjust Match Grain as needed. Not bad in this case.

Using Noise for Grain

Prior to the addition of Add Grain and Match Grain to version 6.5 Professional, the typical way to generate grain was to use the Noise effect. The main advantage of Noise effect over Match Grain is that it renders 20 times faster. The downsides are that After Effects doesn't make it easy for you to separate noise channel by channel, nor can you hold out noise to foreground elements only while viewing the background. Scaling it requires a separate effect. But adding grain is one of those areas where you can often get away with less than 100% accuracy.

You can use three solid layers, with three effects applied to each layer: Shift Channels, Noise, and Transform. You use Shift Channels to set each solid to red, green, or blue, respectively, set their Blending Modes to Add, and set their Opacity very low. Next, set the amount of noise and scale it in the Transform effect.

If the grain is meant to affect a set of foreground layers only, hold them out from the background plate either using pre-composing or track mattes. If this sounds complicated, it is, which is why Match Grain is the better choice if it's available.

Removing grain, or sharpening an image in general, is a completely different process from adding grain. Typically on a production that has been well shot, however, you'll rarely have a reason to reach for the Remove Grain tool.

If you do, your reason will probably be unique to your particular footage. In such cases, you may very well find that Remove Grain at the default settings gives you a satisfactory result. If not, check into the Fine Tuning and Unsharp Mask settings to adjust it.

Remove Grain is often most useful sort of “behind the scenes,” in other words not across the whole final shot (Figure 9.31), or in combination with other effects. If you're using Remove Grain to improve the likelihood of a clean blue-screen or green-screen key, apply the resulting matte back to your source footage as an alpha track matte. That way you get the best of both worlds: a clean matte channel and realistic grain on the source color layer.

Figure 9.31. Although it may look nice for a still figure in a book, the results of Remove Grain applied to the whole shot at the default settings are rarely what you want. The solid with the Ramp effect now matches quite well with no grain applied to it whatsoever, but in full motion the grain-reduced shot looks a bit strange and retains a certain soft lumpiness. Still, it's a powerful tool if you need it, and you can certainly dial it back.

Note

Chapter 10, “Expressions,” offers a unique and highly effective strategy for removing extreme amounts of grain from a locked-off shot using expressions.

The most obvious time to add grain to a layer is in cases where the layer is computer-generated or a still image. In either case, it will lack any of the moving grain that you would find in film or video footage. Pixar does not add grain to its final shots because they are internally consistent; none of the shots originated on film or video, so they all lack appreciable grain. As soon as your shot has to match anything that came from a camera, and particularly if it's going to be projected, you need to manage grain.

You also may have to add grain to an element if it has blur applied to it. Blurry source shots can still contain quite a bit of grain over the blur because the grain is an artifact of the medium recording the image, not the subject itself. Elements that are scaled down in After Effects also have the grain scaled down, another case in which it may be necessary to restore it.

Blue-screen footage that has been keyed may also need grain added. Remember, the blue channel contains more grain, typically, than red or green. Suppressing the blue channel in a color key operation, therefore, can also suppress grain too much for it to match other footage.

Other compositing operations can enhance the grain of an element. Sharpening, if it is not done via the Remove Grain tool, can strongly emphasize grain contrast in an element, typically in a not-so-desirable manner. Sharpening also brings out any nasty compression artifacts that come with footage that uses JPEG-type compression, such as miniDV video.

Lack of grain, however, is one of the big dead giveaways of a poorly composited shot. It is worth the effort to match the correct amount of grain into your shot even if the result isn't apparent as you preview it on your monitor. Especially when outputting to film, but even with video, elements with the wrong amount of grain stand out unpleasantly and fail to look natural.

Garbage in, garbage out isn't a new principle. But what does it mean in this context? Here are some specifics (with details following):

The most radical thing you can do on set to ensure a good result when shooting miniDV or HDV video is to aim for a low-contrast master that looks horrible to the director of photography. As Stu Maschwitz said about shooting this way, “The on-set monitor [is] not the answer print but the negative.” Whites in particular, once blown out, are impossible to recover (Figure 9.33).

Figure 9.33. Sunsets are notoriously difficult for digital cameras to capture. Once those hot areas of the image are blown out, they're not coming back, nor is detail returning to the foreground. Even in lower-contrast images, as the color levels approach full white or black, you lose all room to maneuver in After Effects. This problem is a centerpiece of Chapter 11.

Most camera operators would be inclined to deliver an image on set that looked as close as possible to how the final should look. This is often an appropriate strategy with film. With digital video, however, shooting a low-contrast source leaves ample room to bring out a high dynamic range using tools such as Levels and Curves in After Effects.

Many artists would argue this point, but I'm going to go out on a limb and say it straight out: If you want your footage to look filmic, the frame rate had better be 24 fps.

One of my favorite demonstrations of the difference between 24 fps film and 60 field per second NTSC video dates back to the Golden Age of television and is available on DVD. In 1960, when the original Twilight Zone was in production, the crew decided to shoot on video rather than film during the second season as a cost-cutting measure.

The experiment lasted six episodes (“Static,” “Night of the Meek,” “The Lateness of the Hour,” “The Whole Truth,” “Twenty-Two,” and “Long Distance Call”), then was abandoned. The difference in how the drama “reads” on video versus film is simply incredible. The video versions are almost like watching a soap opera; the film versions retain all of the spare, noir ironic distance and mystique that made the series famous. In short, the videotaped versions have immediacy, but the film versions seem timeless.

If you're with me on this, but you're still faced with shooting NTSC video, consider carefully if there's any way to capture your footage using the slower frame rate. It is certainly possible to convert 29.97 fps video to 23.976 fps (other-wise known as 24 fps), but the resulting motion will stutter as every fifth frame is skipped. Many contemporary video cameras include a 24 fps mode; prior to that, digital filmmakers would use 25 fps PAL format cameras and slow the footage down to 24 fps. These options are worth considering.

Again, if the immediacy of the reality television look is what you're after, by all means, go for it: Shoot your source with a consumer video camera and match elements to that. It's not a question of better or worse, it's a question of immediate versus timeless.

Note

The numbers “1.85” and “2.35” referred to the ratio of the width to a height of 1, so it's the same as saying 1.85:1 or 2.35:1, respectively. The 16:9 format, which has become popular with digital video, is equivalent to a 1.77:1 ratio, slightly narrower than Academy, but wide compared to the standard television format of 4:3 (which translates to 1.33: 1). See Chapter 11 for more on this.

As the world transitions from standard definition to high-definition broadcast television, formats are making the same transition that they made in film half a century ago. The nearly square 4:3 aspect ratio is giving way to wider formats: 16:9, 1.85 Academy aperture, even 2.35 Cinemascope, and who knows what next.

Big-budget films are often made for more than one format, and you can do the same with some preplanning. When the film is intended both for theatrical release and the home video market, all of the effects might be created at a 4:3 aspect ratio and then masked off for the wider theatrical version. This is fine as long as you're aware at every stage of production what the safe areas of your frame are. For example, on The Day After Tomorrow the theatrical mask sat near the top of the frame, so that all of the less-essential action had to be planned for the bottom of the frame. This one had the nickname Ueli-mask, after the film's cinematographer, Ueli Steiger.

The influence of color decisions on the final shot, and by extension on the story being told in the shot, is a big topic, discussed by cinematographers and colorists the world over. Trying to distill it into a few pithy paragraphs here would do it a disservice.

So here's a suggestion: If you're new to the idea of developing a color look for a film or sequence, get reference. Study other people's work for the effect of color on the mood and story in a shot, sequence, or entire film. Figure 9.34 is taken from an independent short film series shot on DV but intended to parody the look and attitude of big budget action movies; the transformation of before and after is fairly radical.

Figure 9.34. Radical color transformation is undertaken to give this no-budget action movie parody the feel of one of the films it satirizes. Techniques such as using a color solid to transform the lighting and color of footage are explored throughout Chapter 12. (Images courtesy of markandmatty.com.)

You can find third-party plug-ins dedicated specifically to lending a film look to video. Many are dedicated to the first motivation for creating a film look: They can make your shot look grainier, scratched, vignetted, jittery, and generally like it was shot with the oldest, most poorly maintained film camera in the world, with the negative being dragged across the floor of the lab and stepped on for good measure.

Reliable methods for fabricating the expensive film looks of twenty-first century Hollywood, however, are harder to come by. Stu Maschwitz developed the Magic Bullet Suite (a set of plug-ins for After Effects and Apple's Final Cut Pro) so that The Orphanage could help filmmakers who want to shoot on cheap and easy miniDV cameras, but who demand the look of film; thereafter, the software was made publicly available. Amongst the suite's many tools are Magic Bullet, which converts video footage to 24 fps with special emphasis on de-artifacting, and Look Suite, which contains preset looks designed to match existing film styles and processes. There is no direct replacement for these tools (which you can check out for yourself on the book's CD-ROM), but Chapter 12 looks at simpler ways to match certain looks.