INSIDE 3DS MAX® 7 [Electronic resources] نسخه متنی

Video Post

With all of this discussion about compositors, don't be dismayed if you think that you don't have access to one. There's a solution right inside 3ds max itself! Video Post will not only handle postprocessing effects and composition but will manage the render for you as well. This unification allows you to skip the step of rendering the file beforehand.

That's the good news; the bad news is that these tools aren't really industrial strength when it comes to production. You shouldn't try to do the editor's or the compositor's job; concentrate on your own, which is getting the pretty pictures to come alive. Even if you are the only one involved, it's much better to use dedicated software for editing and compositing. The quality of your work will improve, as well as your peace of mind.

Video Post is accessed by selecting it from the Rendering menu. It comprises two main parts: the Queue, on the left, and the timeline, on the right (Figure 21.32). The timeline has range bars to specify when the Queue entry will be added into the mix. For a given frame, Video Post goes down the Queue list and, if an entry is in range, processes it.

Let's go over the Video Post components:

New Sequence
This button wipes the Queue clean and allows you to start over.

Open Sequence
This button allows you to open a saved Queue. Great for experimenting with different effects and Video Post methods.

Save Sequence
This button saves a Queue as a .vpx file. It's probably better when experimenting with different effects settings to save your scene as a separate .max file, however, as you will probably make changes to your scene in areas other than just the VP Queue.

Edit Current Event
This button accesses the Edit dialog for the selected event, allowing you to make changes to its attributes.

Delete Current Event
This button removes the entry from the Queue. There is a warning dialog to help avoid erroneous deletions.

Swap Events
This button reorders two selected Queue entries.

Execute Sequence
This button starts the Video Post rendering process.

Edit Range Bar
This switch allows for editing of the range bars; it's typically always on.

Align Selected Left
This button aligns multiple ranges from the left; each range stays the same length as it was before.

Align Selected Right
This button aligns multiple ranges to the right; each range stays the same length as it was before.

Make Selected Same Size
This button aligns multiple ranges both left and right; the ranges all change length to equal the first Queue entry.

Abut Selected
This button moves the lower range so that it starts immediately after the upper range. An excellent tool to use for switching cameras during rendering.

Add Scene Event
This button adds a rendering sequence from within the project. The rendering can be made from either a viewport or a camera, but it's best to stick with the latter, as a viewport can always change.

Add Image Input Event
This button adds an exterior file, animation, or sequence. Another way to render over an animation or to add titles to a rendering.

Add Image Filter Event
The fun part of Video Post; here's where you add all the effects.

Add Image Layer Event
This button gives you the following menu of ways to combine layers:

• Adobe Premiere Transition Filter
  Uses the set of Premiere filters, if you have the software installed on your system.

• Alpha Compositor
  Adds the top image to the bottom, cutting around the top's alpha channel. Note that this doesn't apply an overlay but carries out an additive process. The gain of the final image is very bright.

• Cross Fade Transition
  Fades from one image to the next.

• Pseudo Alpha
  Attempts to make an alpha channel composite out of the luminance of the top image.

• Simple Additive Compositor
  Adds one image to the other in an unpredictable manner that you probably won't like.

• Simple Wipe
  A scene transition horizontal wipe à la Premiere.

Note

You might have guessed by now that these last effects are not among the author's favorites. They are legacy code from the old 3D Studio DOS days, they can be very frustrating to use. They also don't work well with files from Photoshop, especially the alpha channels.

Add Image Output Event
This button adds the final entry in any Queue, the output to a file. Without it, the sequence renders only to RAM and the Rendered Frame Window.

Add External Event
This button adds external code to an event, executes a batch file, or copies to and from the Clipboard.

Add Loop Event
This button adds a loop or ping-pong action to a parent event. You could use it to cause a short animation overlay to repeat itself for the length of the render.

Standard 3ds max window tools
The controls on the bottom of the window are the standard 3ds max window controls: Pan, Zoom Extents, Zoom Time, and Zoom Region.

All these tools can be powerfully combined to get great effects for your 3ds max 7 renders. In particular, glowing effectswhich are applied as image filter eventsprovide for rewarding eye candy.

Adding Filters

The scene is set: an exterior shot of the mad doctor's lair, on a dark and stormy night. But waitas you can see from Figure 21.33, the light coming out of the windows doesn't convey unspeakably horrible experiments; it looks more like a candlelit dinner with an alluring assistant. The following exercise shows how we can use Video Post filters to give the windows an eerie glow and handle other glowing objects (Figure 21.34).

1.	Open the file called lab01.max on the DVD. From the File menu, choose Save As, point to an appropriate subdirectory on your hard drive, and click the plus-sign button to save a new file with the name incremented to lab02.max.
2.	Press the M key to bring up the Material Editor. Select "glass" from the list of materials. Click and drag down the Material Effects Channel button (the small 0 just under the material swatches). You have a choice of 16 channels; set the number to 1 (Figure 21.35). Figure 21.35. Changing the Material Effects Channel to 1. Note At this time, all instances of the glass material will be assigned Material Effects Channel 1. That is, anytime we wish to access the same effect in Video Post, we must assign the object this material. There is a meteor streaking by in the background that we don't really want to be a glass object. We'll assign an ID in a different fashion, by Object ID, in the next step.
3.	Using the Select by Name tool, choose the meteor object. It's a tiny object out at the edge of the scene, and out of frame of the Camera view (Figure 21.36). Figure 21.36. The meteor object has been selected.
4.	From the Edit menu, select Object Properties. Another way of getting the Object Properties dialog is to right-click in the viewport and then to select Properties from the menu.
5.	Change the G-Buffer Object Channel setting to 2, and click OK (Figure 21.37). Figure 21.37. Changing the Object Channel setting to 2. Note It doesn't make any difference whether you use the Material Effects channel or the object channel; the effect will be the same. Personally, I tend to use the Material Effects channel, as it is easier to find all the instances of an effect for global changes. You wouldn't want to have to individually change every firefly in a swamp scene!
6.	From the Rendering menu, select Video Post. Click the Add Scene Event button (the strange cyan "teapot" icon in the Video Post's upper toolbar). Leave the settings where they are, and click OK (Figure 21.38). Figure 21.38. Adding a scene event. [View full size image]
7.	We can see only the first 30 frames or so. To be able to see the entire range, click the Zoom Extents button in the Video Post's lower toolbar. Note Notice that the scene event (Camera01) runs for the entire 100 frames of our animation. It is of vital importance that this parameter be checked prior to the final rendering. If you increase the length of the animation, the scene event will not automatically extend with it. It will be like trying to shoot film with the camera turned off.
8.	Click the Add Image Filter Event button to bring up the Add Image Filter Event dialog (Figure 21.39). From the Filter Plug-In drop-down menu, select Lens Effects Glow. Click OK (Figure 21.40). Figure 21.39. Adding an image filter event. [View full size image] Figure 21.40. The Lens Effects Glow filter selected.
9.	Making sure that you haven't selected any of the Queue entries, click the Add Image Output Event button. In the Image File section, click the Files button. Save your file as labtest.avi in an appropriate folder on your hard drive. The default Cinepak codec will be fine for this exercise. Keep clicking OK to close the dialogs until you are back in Video Post.
10.	Double-click the Lens Effects Glow entry in the Queue. Click the Setup button. The Lens Effects Glow dialog appears. Click Preview, then VP Queue. After a pause, the scene appears in the Preview window.
11.	Change the Object ID setting to 2, and check the box in front of Effects ID (it should read 1). A slight glow will appear in the windows (Figure 21.41). Figure 21.41. The initial setup of the Lens Effects Glow filter.
12.	Click the Preferences tab. In the dialog, set the Size at 2 and press the Tab key. It may seem contradictory, but lowering the glow size makes the effect more pronounced. The windows now have a suitably evil glow.
13.	Leaving the dialog open, advance to frame 37. When the scene updates, you will find that your meteor, which is now in frame, is too dim to see. Lens Effects Glow isn't powerful enough to light it properly. Click OK to close the dialog. Note When lens flare filters were first developed, they were overused to the point of being ridiculous. As quickly as they were adopted, they were shunned. Used properly (and tastefully), they are a powerful tool, lending a sort of "super glow." If a bright light like car headlights or a flashlight shines directly into the camera, consider the much-maligned lens flare.
14.	Making sure that nothing in the Queue is selected, add another image filter event. This time, select Lens Effects Flare from the drop-down menu. Click OK, and drag the Flare up the Queue one slot, so that it is below the Glow filter.
15.	Double-click the Flare filter, and click Setup to open the Lens Effects Flare dialog. Click the Preview and VP Queue buttons. Initially, the flare shows up, then disappears after the scene renders. Click Node Sources, then select "meteor" from the list. Click Update to see the changes.
16.	We just want a small meteor, not Armageddon, so change Size to 22 and Intensity to 44, and clear the Streak check box in the Render column, near the bottom of the dialog. The meteor shrinks to a more appropriate size (Figure 21.42). Click OK to close the dialog. Figure 21.42. Full setup of the Lens Effects Flare filter. [View full size image]
17.	Your Queue should look like Figure 21.43. Click the small running man icon to start the rendering process. Make sure that 0100 Range is selected, and set Output Size to 320 X 240. Click the Render button, and your file should start rendering shortly. Figure 21.43. The completed Video Post Queue, ready to render. [View full size image]

You can check your work with the lab01finished.max file on the DVD, and view the labtest animation there, as well.

Note

Notice that as the file renders, a separate pass is made for each filter. Sometimes, filters can interfere with one another, giving undesired results. Juggling them around in the Queue can sometimes help this problem.

These filters operate on the intensity of the rendered pixels, not the materials attached to the geometry. If you open labtestLightning.avi from the DVD and look at the window glow during the lightning strike, you can see that the effect is way amplified. Glow intensities, like most parameters in 3ds max, can be animated in the Dope Sheet. A resourceful animator could make the glow lessen when the lightning strikes.

Now we'll temporarily digress from Video Post to cover probably the most important form of post effect: motion blur.

Motion Blur

When objects or cameras are moving in the scene, the scanline renderer is digitally sampling their positions as each frame is rendered. As is often the case, movement takes place when the "shutter" of the virtual camera is open. This movement is compensated for by a blurring in the image. Not using motion blur with your renderings will, at best, produce an unnatural-looking crispness or a stroboscopic effect. At worst, heavily pixelated surfaces will take on a seething, boiling look. A fly-by of that granite countertop will look like millions of ants at a rave party!

Adding motion blur is not without its penalties, however. Some speed hits will be experienced, depending on the type of blur used. As these slowdowns can be quite dramatic, a careful study is necessary to get an acceptable output within the time constraints of the project.

3ds max allows for the use of four types of motion blur: Object, Image, Multi-Pass, and Scene. These effects are applied in various locations throughout 3ds max 7, so let's cover them one by one.

Note

The mental ray renderer has its own form of motion blur.

Object Motion Blur

Probably the easiest of the blurs to use is the Object Motion Blur. This is strictly for objects and not for simulating camera blurs. It's best used with a fast-moving object and a still camera. While the still rendering of the jet in Figure 21.44 looks pretty good, you can see the jittery quality of the movie if you open up MBnone.avi from the DVD. We'll fix this in the next exercise, when we add Object Motion Blur so that an individual frame looks like Figure 21.45.

You can also see the results of the motion blur by watching the objectMB5.avi movie from the DVD.

The controls of Object Motion Blur are fairly easy to figure out. The Samples setting controls the number of snapshots of the object. The Duration controls how long the blur lasts, and it is "center weighted" to the middle of the frame, temporally speaking. The duration subdivisions number is usually left as equal to the number of samples.

The application of motion blur is much more an art than a science. Adding no blur, especially if the 3D rendering is to be composited onto live footage, won't look good at all. Adding too much can be problematic as well. If you open objectMB1.avi, you can see how increasing the duration of the blur has created a smeared effect. In some cases, this can be used to show very great speed, such as a faster-than-light superhero. With all forms of motion blurring, usually a little goes a long way.

Image Motion Blur

The real workhorse of 3ds max's motion blurs is Image Motion Blur. It's also one of discreet's favorites, as virtually the same code is used in its compositing product, combustion. You'll find that it is the blur of choice for most situations (Figure 21.49).

Image Motion Blur is created by applying a postrendering smearing effect, rather than by superimposing samples over one another. The blur can be applied object by object or to an entire layer. The mechanics of the process are virtually the same as with Object Motion Blur.

Image Motion Blur has another point of superiority over its brother Object; it takes into account camera motion. Notice in Figure 21.50 how the blur angle is quite different from the original's. This more closely resembles what would happen in real life with a camera lens. The file that created the image is motion blur-image.max, and can be set on frame 16 for a view of the jet.

The controls that operate the blur are basically Duration (found in the Renderer panel of the Render Scene dialog, the same as in Object Motion Blur) and the Multiplier (in Object Properties). The Multiplier parameter increases the smearing along the axis of combined motion. You may also choose whether the effect works through transparencies, or whether it interacts with an Environment background. If there is camera movement, you should definitely check the Apply to Environment Map box.

Multi-Pass Motion Blur

This next blur takes place by means of the camera. The entire scene is rendered multiple times, and the results composited. It, and Scene Motion Blur, are the most time-intensive solutions (Figure 21.51).

Note

Many compositing programs, including discreet's combustion, can add pixel-based motion blur in postproduction. As it has noting to do with multiple rendering passes, it is a fairly speedy process. If you get into a time crunch, this can be a good alternative to lengthy renders.

An interesting aspect of this blurring system is that the results can be seen directly in the viewport by clicking the Preview button. The attributes of the Multi-Pass Motion Blur are accessed in the individual camera's Modify panel (Figure 21.52). A good way to think of this process is to imagine that the camera is taking multiple exposures; when they're added up, the amount of light in the scene must be correct. The number of exposures is specified by the number of passes. The Bias number establishes temporal weighting, either early or late in the frame; 0.5 is right in the middle. Dither Strength is how much each of the passes are blended together, and Tile Size controls how much of the image is rendered at a given time; notice that as the image is coming up, it looks somewhat checkered.

As the application of a Multi-Pass effect is fairly straightforward, there is no exercise. A file has been provided for you to experiment with: motion blur-Multipass.max. If you go to frame 16, you can see the jet in the middle of the frame.

Scene Motion Blur

Our final entry in this tour of blurs is Scene Motion Blur, accessed in Video Post. Like Multi-Pass, this blur renders the entire scene multiple times. Though time-intensive, it is typically used with large camera moves when Image Motion Blur is impractical to use on a pre-object or layer basis. Image Motion Blur has a tough time when one blurring object passes behind another object. Scene Motion Blur is also a dramatic effect, and it is best used when you want to leave speed trails behind objects.

If you open up labNoMB.avi, you can see that the animation has a near-lethal case of the sizzles. As you can see when comparing it to labtest.avi, the camera move is the culprit. Yet it helps the scene visually and could be a great bridge into the next shot, perhaps an interior of the lab.

Excessive bump mapping, as in the labNoMB.avi example, is a sure-fire cause of sizzling. In some cases, faraway objects can sometimes almost jump up and down! Turning down the amount of bump mapping can alleviate the problem before rendering time. We'll do that, and apply a combination of blurs, to get the scene right.