How to Create & Import a Dynamic Mask?

Soniclight wrote on 3/11/2010, 7:55 PM
First, I have VP8.

Second, the reason I'm wanting to sidestep using Beziers in Mask track in Pan/Crop is due to tracking:
I would have to create so many keyframes it would be a nightmare to edit.

Third, I don't have Photoshop but do have Corel PhotoPaint and Gimp 2.
Combined together, I can do quite a bit in creating PNGs via PSDs.

So what kind of "dynamic mask" am I referring to?
Scenario of hypothetical:

Think phases of the moon.

I would have a sphere on which I wish to progressively start from sliver crescent to half-moon illumination. Track-wise, this would mean that there would be two moon tracks: top would have the progressive lightening happening, bottom would be the "moon in the dark."

Sound easy, right? Use Cookie Cutter.

Well, not if one is doing a beauty pass of said moon where it is receding or moving towards the viewer. It would also turn into a lotsa-and-lotsa keyframes and the small position graph in Cookie Cutter is too small for precise stuff, IMO. I'd rather be able to manipulate a PNG file.

The other issue is that I'd like something equivalent to what one sees in the mask track of Pan/Crop -- a kind of transparent mask.

That is, I need this mask to act like the Cookie Cutter does because... the "dark side" of the moon track underneath also happens to have stars in the area of the mask of the track above it: I can't have the mask on top track block out the stars of the lower track such as one would have with a basic Chromakey.

Maybe this is where turning the track to Add or Subtract or Multiply or something comes in also.

So there are two issues here:

A) How would you create and import a fluid "phases of the moon" mask as a file, i.e. PNG or...?

B) What track modality and/or make-it-transparent mode would work best so as to not interfere with track below it?

Maybe I'm over-complixicatin' this and asking the wrong questions.
In either case, thine help appreciated, oh ye wise wunes.


~ Philip


farss wrote on 3/11/2010, 8:50 PM
The task sounds pretty simple but first you need to get your head around using compositions. Vegas doesn't have these like AE does, Vegas has Nesting, pretty much the same deal just not quite as easy to work with but gets the job done and the principal is the same and I probably use more composites in AE than migh be needed but they're a huge help to the brain.

So task 1, create your moon ignoring everything else, all you are going to achieve in this project is having the moon change phases. Get a static shot of the moon. A Bezier mask should be all you need. The shadow the eath casts onto the moon is just one sphere occluding another. OK, we're not working in a 3D app so we've got to fudge it BUT you only need a couple of sets of keyframe. It's just one circular mask moving over the circular moon. As it moves the diameter of the mask changes and so does the feathering. One of the keyframe interpolation modes in Vegas should help pull this off.

So now you've got a project that creates you static waning moon. Bring that into a new project (nest it). Bottom track your starfield, next track you waning moon. OK here's a problemo, track two is going to play havoc with your star field. No problem, a cookie cutter with a soft edge will mask out just the moon on track two.

Now you need you moon to move. Track motion on the moon track handles that.

You want your moon to move towards or away from the viewer, use event pan/crop on your moon event to change its size.

Obviously you can add more, like change the color of the moon with the phase, CC should take care of that.

Now I can't say the above will nail it for you 100%. Just trying to show how to break seemingly complex composits down into simple components and make them all work together. No matter which app you use and how much firepower it brings to the party analysis is the key to success.

Tattoo wrote on 3/11/2010, 9:32 PM
As a big fan of science, I can't allow this minor brain-fart to pass. The earth's shadow on the moon creates a lunar eclipse, not the phases of the moon. The phases are the result of seeing the dark side of a lighted sphere from different angles. Sorry ... I know you know that, Bob, I just can't let that go ...

I'd refine Bob's suggestion with the following:
- get a great picture of the full moon as suggested (lots of great pics on APOD site (google it))
- make a copy & mess with the brightness/contrast/etc to bring it down to a very dark version (as if illuminated only by earth-glow & starlight)
- put the dark moon behind the full moon
- key frame the phases
-- I think a vertical line with 3 points (top, bottom, middle) & then connected around the moon would give you a "half moon"
-- then move forward/backward as required & keyframe the middle point of the line at the full, 3/4, 1/4 & new moon phases, using the bezier curves to make resemble the sphere that it is

I would think that Vegas would make a decent interpolation between your 5 keyframes to animate your phases. Throw a circular cookie cutter on both tracks to eliminate everything but the moon on both and I think you're there. Everything else just like Bob suggested.

Soniclight wrote on 3/11/2010, 9:36 PM
Too late in the day for me to digest at this juncture, Bob, but I'll definitely come back and study your thoughtful here's-a-way-to-pull-this-off tutorial :)
Soniclight wrote on 3/11/2010, 9:47 PM

I agree with your correction on what a phase of the moon is and is not (vs. Earth shadow thing) -- and that is what I wish to do. But I'll also have to come back and study your addendum tomorrow or whenever-later.


I used the easy-to-grok moon hypothetical just as that, a hypothetical. I'm not going to apply it to the moon but actually the Earth; I didn't want to complicate the question. I just wish to have a ready-to-go wax/wane mask I can pull out and use on whatever spherical/curved/non-linear horizon line I need it for.

So moon or no moon, your combined responses will move me toward a solution.
farss wrote on 3/11/2010, 11:25 PM
"Sorry ... I know you know that, Bob, I just can't let that go ..."

Was indeed a complete brain fart. Something in my head was going "hang on a minute..." but I was arguing with a printer at the same time.

No need to keyframe phases. The shadow moves continuously.

I've been doing a few revolving earths in AE of late, both solid and hollow, if anyone wants a rendered one drop me a PM.

BudWzr wrote on 3/12/2010, 6:45 AM
I am wondering if say a 30 sec clip was needed, and you created a 60 sec duration and time compressed it (two renders needed), if this would improve interpolation?

richard-courtney wrote on 3/12/2010, 9:13 AM
Try this:

Use this image to start:

Use Sony Bump Map FX. Light type Spotlight
Set a keyframe with:
Intensity: 0.344 Focus: 0.544
Ambience, shineiness, and Bump Height to zero
Src: X: 0.447 Y: -1.325 Z: 0.760
Dst: x: -1.213 Y: 1.247

Set another keyframe changing: Dst: X: 1.181 Y: -0.117
You may need to drop Intensity midway between your keyframes.
Soniclight wrote on 3/12/2010, 7:36 PM

Thanks. I did as you suggested and definitely had a "Hmmm... would never have thought of using a Bump map" moment. This could be a way to do this; all I have to do is translate this process to whatever curved horizon line I have.

Further experimentation of this and what others have suggested to unfold. And I also realized overnight that since the purpose is to ultimately mask out Particleillusion effects washing over the Earth and landscapes--and especially their highlights on terrain below, I can also work with Area Mask in PI.

... And since I recently purchased the 3D terrain prog Vue Complete, there may be other crafty ways to noodle things around.

One way or another I'll figger this out.
TheHappyFriar wrote on 3/12/2010, 10:19 PM
I found the phases of the moon taking ~30 minutes with biezer mask tool:

I used this pic to base my mask on:
big pic here!

Veggie @ the bottom of the page:
Soniclight wrote on 3/13/2010, 1:30 AM
Thanks, HappyFriar/Stephen, for pic and .veg. Looks like I have more than enough ways to come up with something decent. I may post a draft/working clip here at some point to show that I've learned and applied the schoolin' here :)