[Blaise Douros]

I don’t think there’s any keyboard shortcut for what you want to do. I was thinking you were trying to sync up two separate multicam source sequences, but it sounds like you’re just setting up multicam sequences for normal use. Is there no reference audio from the camera? Premiere can sync by matching audio tracks.

If this is a workflow you’re going to be using a lot, then speaking to the producer about using genlock on set would be pretty useful–that way you could just sync all your clips in the multicam sequence by timecode and walk away. Alternately, having even one track of camera audio to use for sync purposes, so you don’t have to do it manually, would be enough, too.

Either of these would save them a ton of money on your time in post, and in particular, a camera audio reference track would be incredibly easy for them to add on set. It would be a win/win.

[Blaise Douros]

What if you made B a very bright color, and then Chroma Keyed it out? Then A would occlude it when in front, and be hidden by it when behind. Precompose it and place over your background, apply the key to the precomp, and you’d be done.

[Blaise Douros]

Why not just import the contents of your second Multicam track into the first? If you’re using (for example) four shots per Multicam sequence, couldn’t you just drop all eight into one? Then you’d be able to see sync in your Multicam viewer, without toggling tracks.

[Blaise Douros]

Just take the layers from each of these compositions, and combine them into one. The topmost layer should be the version with the Alpha Matte–you can precompose it if necessary. Then you should be able to use the ink movie as a luma matte to reveal the colored logo, and a luma inverted matte to hide the white foreground.

[Blaise Douros]

You wouldn’t be able to control the transparency individually–only across instances of the repeater. So if you created a line of dots, you could make each one fade gradually down across the line. Then, if you’d duplicated the line, each line would follow. So they’re not the kind of truly granular changes that will let you control each one, but you can make cascading changes across the set.

I know this doesn’t perfectly solve your problem, but it’s something that might solve part of it.

[Blaise Douros]

You could probably get some mileage out of creating a sphere Shape Layer, and then using repeaters to create the dot grid. You can even control the transparency across each repeater instance, though it wouldn’t work for color.

[Blaise Douros]

If you’re working with the manufacturer, ask them what the refresh rate is for the LED. If they’re using Pulse Width Modulation to moderate the brightness, knowing the rate of the pulse will be important. PWM means that in order to modulate the apparent brightness, instead of reducing the voltage, the LED is pulsed on and off: so if they want 50% brightness, they pulse the LED so it’s only on 50% of the time, which our eyes read as dimmer.

If they are using PWM, setting the screen to its highest brightness setting will probably help–sometimes that sets the LEDs to “always-on” instead of flickering at high speed.

Ultimately, you’ll need to shoot in the correct delivery frame rate–but you can change your shutter speed to your heart’s content. A slower shutter is probably going to work better, in this instance. If you’re shooting at 1/50th shutter over 23.976 fps, try slowing the shutter down to something close to the framerate–1/30th or 1/24th if your camera will do that.

Basically, what’s happening is that the LED is blinking at a different speed than the camera’s shutter, so each frame is capturing varying brightness levels across frames. Slowing the shutter down allows the camera to expose more evenly across frames.

[Blaise Douros]

Just for clarity–the expression above does use a 2D null, connecting to a 3D layer. Walter’s solution is also pretty elegant, so I don’t have much to add, except that mine can do what you want by simply adding two minus signs:

x = lookAt(transform.position, thisComp.layer("Null 1").transform.position)[0];
y = lookAt(transform.position, thisComp.layer("Null 1").transform.position)[1];
z = transform.orientation[2];
[-x,-y,z]

As for ensuring that the edges of the rear interface layer don’t appear on screen…set Null 1’s position to [0,0] (i.e. the farthest possible position from center), then set the z position and scale of Layer 1 so the maximum angle is as desired and the edges aren’t cut off, and Bob’s your uncle.

14264_lookattestexpression.aep.zip

[Blaise Douros]

I originally had written something else, but realized my mistake–see above ^^

[Blaise Douros]

Here’s a thread with a useful expression for doing this: https://forums.creativecow.net/docs/forums/post.php?forumid=2&postid=1094295&univpostid=1094295&pview=t

I futzed with this a little. Put your interface layer in 3D space, back it waaaay up in Z space, and scale it up so it fills the screen. Then put this code in the “Orientation” expression of the interface element, where Null 1 is your Null on a 2D layer.

x = lookAt(transform.position, thisComp.layer("Null 1").transform.position)[0];
y = lookAt(transform.position, thisComp.layer("Null 1").transform.position)[1];
z = transform.orientation[2];
[x,y,z]

This uses the X and Y properties of the Null, and makes the Z property 0 at all times.

To adjust the subtlety of the interface layer’s movement, push it further back in Z space and increase the size for subtle movements, or pull it forward and scale down for more dramatic movements.