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Advice, Please: Make a Building Change Color?

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Phil McCartyAdvice, Please: Make a Building Change Color?
by on Aug 18, 2009 at 8:23:38 pm

Hi, I am trying to find a way to make a stationary shot of a building change color, gradually (say, 3 seconds.)

My initial thought is effective but bland, to overlay a copy, and roto out the building, and then make it green, and then do a wipe from one end to the other.

I am new to this, and am wondering if anyone has an ideas on how to "jazz it up", maybe by doing something cool/funky at the edges? Or some sort of pixelation or .. I'm not sure. Is there a tutorial out there which might teach some translatable skills?

Thanks,
Phil


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Michael SzalapskiRe: Advice, Please: Make a Building Change Color?
by on Aug 19, 2009 at 1:01:31 am

Your initial thought (to have a copy of the building on a separate layer) is a great way to start. How you reveal the new color on the other hand... There are literally thousands of different things that the people on this forum could suggest. What is supposed to be causing the building to change color? The motivation could suggest a solution.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Phil McCartyRe: Advice, Please: Make a Building Change Color?
by on Aug 20, 2009 at 11:05:16 pm

Ooh, somehow I didn't get the notification that you'd responded:

Well, there's a person running through the scene, from various angles. Towards the camera, away from the camera. And I'd like the "spread" to happen as he goes through, or shortly thereafter.

Phil

Here's a sample shot:
Runner


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Michael SzalapskiRe: Advice, Please: Make a Building Change Color?
by on Aug 20, 2009 at 11:56:56 pm

What's supposed to be causing the change in color though? Is it the pure spirit of sport emanating from the runner? Or is he being chased by some dark evil?

Anyway, if you're after what I think you're after, I would use a layer with some nice organic movement as a track matte for your color changed layer. Maybe some footage of ink in water (from Digital Juice's Compositor's Toolkit perhaps).

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Phil McCartyRe: Advice, Please: Make a Building Change Color?
by on Aug 21, 2009 at 12:17:30 am

Michael (Aka The Great Szalam)

First, thank you for helping me with this. You might not think you're great, but being willing to help me with this is pretty fantastic, so I appreciate it.

Second, you blew my mind a -little- bit. I'm a little rusty with AE, I worked through the Total Training (back when it was AE...5, maybe 6), and have done a handful of the VideoCopilot tutorials, but I am not quite as fluent as you are with the terminology and techniques.

I believe I have access to some libraries that have that kind of organic movement, let me do a quick brush up on Track Mattes...

Okay, I checked 4 online tutorials, and while I vaguely understand what they do, none of them give a solid conceptual explanation of what a track matte really is, so I don't quite understand how to apply it in this context.

Track Mattes allow me to use one layer as a either the alpha or the luminance channel for another layer. Does that mean if I have a (lets say) billowy smoke cloud (on a black background) and use that as the Track Matte / Alpha of the Green layer (as the fill) and the regular layer (as the matte) then the green layer would expand using the motion/texture of the billowy smoke cloud?

At least, thats what I think you mean, but I want to confirm. I'll have to make a few calls to see who has stock video. And do I need motion textures w/ alpha channel videos as well?

Thanks Again,
Phil


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Michael SzalapskiRe: Advice...Tutorial with DEMO PROJECT ATTACHED
by on Aug 21, 2009 at 4:04:39 am

A track matte can be done with alpha or with luminance. Are you familiar with layer masks in Photoshop? It's a similar principle.
If you go to Digital Juice's training page for their Compositor's Toolkit and scroll down about three-quarters of the way, you'll see some tutorials called Custom Ink. It's a series on revealing things with track mattes using organic footage.

You could do it yourself without buying stock footage by combining an animated fractal noise effect with ramps and other color corrections over time...but that's not overly important right now.

Let's just try it out for ourselves.
Start a new project. Make a new comp. A normal dv sized comp will be fine for this test. Call this comp, "Main". In this comp create a red solid the same size as your comp. Rename the layer, "Red". Now create a blue solid the same size as the comp and name it, "Blue". (Ctrl+Y on the PC or CMD+Y on the Mac is a shortcut key to create a new solid).

Your layer list should now be:
Blue
Red

Thrilling, right?
Now, create another comp the same size as your existing comp. Call this new comp, "Track Matte Comp" or some other creative title. Create a new solid in this new comp the same size as the comp. (it doesn't matter the color) Apply Effect>Generate>Ramp. You should have a nice black to white gradient.
Back in your Main comp put the Track Matte comp at the top of your layer list which should now look like:
Track Matte Comp
Blue
Red

Cool?

Now, in your timeline window you should have a panel that offers the option to change the layer's blending modes. (If it's not there, there will be a panel with lots of switches for the layers. Underneath that there should be a wide button to click on that will switch that panel to what we want)
On the blue layer, under Trk Matt (or whatever it's called) click that drop down and choose the luma matte option.

WOAH!

Now you've got a red and blue gradient. If you go back into your Track Matte Comp and create a new white solid - say, about 200x200 - and a black one the same size and you offset their positions, you'll be able to see what's going on when you switch back to your Main comp. What's white on the track matte layer will be there and the darker the track matte layer gets, the more transparent the layer will be. If you turn off the eyeball for the red layer and click the little button on the bottom of your comp window that switches between the checkerboard and black for the background, you can see the opacity change that way too.

I hope that made sense.

If not, I've attached an example project here on the COW (219_trackmattefun.aep.zip just click the disc to download it) that fits what I just went over.
(I also included a "more complicated" part that answers your original question about how to use it on buildings.)

I hope this helps!

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Phil McCartyRe: Advice...Tutorial with DEMO PROJECT ATTACHED
by on Aug 27, 2009 at 12:10:22 am

The Very Great Szalzam,

Thanks so much for your remarkably helpful tutorial. I didn't want to write back prematurely, in case I ran into any problems so that I could ask you them all in the one fell swoop. But I figured it out perfectly, with your help, and the effect looks good. I've been using the generated ramps, at the moment, but I will try some stock cloud footage for a more organic fill soon.

As soon as I get a 'finished' version I will upload it so you can see. Thanks so much, I could not have done it without you, and you took a lot of time and energy putting together that project, that was very kind of you.

Phil


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