Motion Tracking in Adobe After Effects 5.5
Page 2 of 3
If you scroll through the timeline, you’ll notice that the numbers count up, not down. This can be very infuriating to any movie villain who has set his bomb to go off when the counter reaches zero. If there were only some way of getting the effect to play backwards...hmmm.
Well, actually there is, with the layer selected, hit Control+Alt+R on a PC or Command+Option+R on the Mac, and After Effects will flip the layer around. This takes the last frame and plays it first, with the end result being that the numbers now countdown. [an error occurred while processing this directive]
Create a new composition that is the same size and length as the raw bomb footage. The easiest way to do this is drag the clip to the Create New Comp icon in the project window.
Add the Countdown Comp to a layer above the bomb footage, and make sure Quality setting for each layer is at best. To make sure our tracking points are set correctly, also set the resolution to Full.
Double click the bomb footage layer in the timeline, which will open the footage in its own window. From the Window Layer Options triangle, choose Tracker/Stabilizer controls.
From this panel you have the option of choosing which tracking or stabilizing you want to do to the footage. Let me take a moment to explain what you now see. The large box on the screen represents the tracking region. The inner box is the Feature region, which tracks the region you will select, while the outer box represents the Search region, that area that After Effects looks at from frame to frame to see if item being tracked has moved there. If we were just tracking as single point, you would see a small cross hair in the middle of the smaller box. This is the tracking point that will pin another layer to that position you are tracking. In general, it is a good idea to make the Feature region and the Search region as small as possible. Otherwise there is a chance After Effects could accidentally jump to another region, thus throwing off the tracking data. After Effects also likes to track data areas that have strong vertical or horizontal elements or have a high contrast.
Since the countdown needs to be pinned to the corners of the label on the bomb, use the Perspective Corner Pin option. This creates four tracking boxes and four crosshairs. We could line the tracking region boxes and the cross hairs with the label because of the strong horizontal and vertical lines of the label that I just mentioned, but there isn’t strong enough contrast or color between the label and the rest of the low noise converter.
Actually there are a couple "problems" with this footage, which could make it fairly hard to track. Because the scene takes place at night, there is very little light in the room, which adds grain to the footage, and because the footage was shot on DV, there are compression artifacts to deal with as well. I’ve already mentioned the poor contrast between the label and rest of the converter. The other thing you might notice right away, is that our shot is zoomed all the way out which makes placing those tracking points extremely difficult.
 |
| There are several "problems" with the raw footage. However, Adobe After Effects can handle these problems very easily. |
Source: Digital Media Online, Inc.
Prev 1 2 3 Next
[an error occurred while processing this directive]
