3D Parent Motion: Moving Planes
A nice 3D effect is the ability to have two videos fly through space parallel to each other. The secret to controlling multiple tracks in unison is to use Parent Motion. For this to work in 3D, all three tracks must be in 3D mode. Let’s see how it’s done.
- We start by pressing Ctrl+Q three times to add three tracks to the Vegas timeline. We’ll name these “3D Parent”, “Front Plane” and “Back Plane”.
- For this tutorial we will add Generated Media but you can use any video you want. Let’s add a Sony Text Generated Media on each track. We’ll also change the background color of the Generated Media Text to make it more easily identifiable.
- Next we want to change the Compositing Mode for all three tracks to 3D Source Alpha. To do this Press the Composite Mode button in the track header and select 3D Source Alpha from the dropdown list.
- Your tracks should look like the image below with all three in 3D Composite Mode
- Now that all three tracks have Track Motion set to 3D Source Alpha, let’s go back to the bottom track (3) which holds the Back Plane and push it back in 3D space. Press the Track Motion button on track 3 and in the Track Motion window, set the Z Position to 240. This will push the video for that track back.
- Now to control the two tracks in unison we do two things. First make tracks 2 & 3 a child of track 1 using the Make Compositing Child button for both tracks. Press the Make Compositing Child button in the track header for tracks 2 & 3.
Your tracks should now look like this:
- Next we need to use Parent Motion to control the child tracks. Press the Parent Motion button to bring up the Parent Motion window.
- This brings up the Parent Track Motion window. First place the interface in 3D Source Alpha mode by pressing the Source Alpha selection dropdown in the upper left corner of the interface and selecting 3D Source Alpha.
- Now you can spin the cube in the large window in 3D space and your two tracks will spin about as well always maintaining 240 units of Z space between them.
Here is the preview window based on these settings
That’s all their is to it. You should be able to use this same technique to build things like a cube of video and control all sides at the same time using 3D Parent Motion. Here is a small video I made of this project using some keyframes on the 3D Parent track.
Here is a link to the Vegas 6 project: 3DParentMotion.veg
Johnny “Roy” Rofrano