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Visualising a composition's FOV within a pre-comp

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Oli da CostaVisualising a composition's FOV within a pre-comp
by on Apr 29, 2013 at 9:04:36 am

Is there a way to visualise a top-level comp's field of view, i.e. the 16:9 window of a top-level comp, within a pre-comp that's being animated?

To clarify, I am animating several parts within a scene in a 10000x10000px pre-comp, which is inside a 'master' comp, with a null controlling the scale and position of the the pre-comp (essentially a pan-scan process), with the master 'seeing' the action within the pre-comp, but obviously only the 16:9 bit that's visible through the master comp's field of view.

As the pre-comp's animations are very complex, it would be great if I could have a dummy layer (say a 5% opacity solid) within the pre-comp that gave me the exact field of view from the master comp (complete with scaling and panning, etc), so that I can concentrate on the animations that are going to be seen in the pre-comp, rather than stuff that will be outside the master comp's field of view.

I am currently only using the active/default camera in each comp and am only working in 2D.

Oli

Oli da Costa
Fraktiv Post Production


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chris brettRe: Visualising a composition's FOV within a pre-comp
by on Apr 29, 2013 at 9:42:56 am

Oli -

- if I understand correctly I think you can do this be having two composition windows open at the same time - one for the master and one for the comp -----chris --


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Oli da CostaRe: Visualising a composition's FOV within a pre-comp
by on Apr 29, 2013 at 10:19:41 am

Hi Chris, yes, that's what I've been doing as a temporary measure, though screen real estate gets somewhat cramped, even with dual screens! Really just interested to know if there was a way to do it within the pre-comp alone, maybe with some sort of expression-driven solution. Cheers though!

Oli da Costa
Fraktiv Post Production


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Tudor "Ted" JelescuRe: Visualising a composition's FOV within a pre-comp
by on Apr 29, 2013 at 11:55:06 am

The only way I can think of is if you would have a camera in your master 16:9 comp, then you create a solid frame size, make it 3d and make sure it fills the frame as you tweak the position to set it in front of the camera and then link it to the camera. This way when the camera moves over your large comp to create the pan, the solid moves with it as well. Turn the opacity down to 10-15% and you have your window.

Tudor "Ted" Jelescu
Senior VFX Artist


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Oli da CostaRe: Visualising a composition's FOV within a pre-comp
by on Apr 30, 2013 at 10:26:43 am

Hi Ted, I think I understand what you mean...will give it a try!

Oli

Oli da Costa
Fraktiv Post Production


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Walter SoykaRe: Visualising a composition's FOV within a pre-comp
by on Apr 30, 2013 at 3:02:20 pm

Here's a fully 2D-solution.

I'm assuming a comp named "LAYOUT" and a comp named "VIEWER" and I'm assuming that you've already dropped LAYOUT into VIEWER.

Add the "Point Control" effect to the LAYOUT layer in the VIEWER comp and duplicate it four times. Rename the point controls (select and hit enter in the Effects Control panel) as follows:

Upper Left
Upper Right
Lower Left
Lower Right

Alt-click the stopwatch for the point property of Upper Left to add the following expression:
fromComp([0,0])

Repeat for Upper Right with the following expression:
fromComp([thisComp.width,0])

Repeat for Lower Left with the following expression:
fromComp([0,thisComp.height])

Repeat for Lower Right with the following expression:
fromComp([thisComp.width,thisComp.height])


Now open timelines for both VIEWER and LAYOUT. Re-arrange the user interface by dragging one timeline tab above the other, so that you can see both.

In the LAYOUT comp, add a new comp-sized solid named VIEWER PREVIEW and change the color, blending mode, and opacity however you like. Add the Corner Pin effect, and alt-click and pickwhip each property of Corner Pin effect to its corresponding point control effect in the VIEWER comp's LAYOUT property. Voila!


So what do those expressions do? They translate the four corners of the VIEWER comp's space to the LAYOUT layer space. You can animate the scale, position, anchor, and rotation of the LAYOUT layer within the VIEWER comp, and the expressions will always translate the VIEWER comp's corners back to local layer space on LAYOUT.

In the LAYOUT comp, since the VIEWER PREVIEW solid layer is the same size as the LAYOUT comp itself, by tying the Corner Pin effect to the local coordinates that represent the VIEWER comp's corners, we can get your FOV preview.

If you make the VIEWER PREVIEW layer a guide layer (Layer > Guide Layer, or right-click and choose Guide Layer) then it will render in the LAYOUT comp, but not in the VIEWER comp.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
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