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Feather the end of a line that draws along a path?

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Kristin Maling
Feather the end of a line that draws along a path?
on Dec 21, 2010 at 9:30:40 pm

Hello.

I have created an animation where I have a line that draws itself along a specified path (ala the old drawing a line on a map from destination A to destination B style), but I've been asked to "feather" the leading end of the line so it's not a hard edge (so that the leading end of the line is actually a gradient from 100% of the line colour through 0%/transparent). Could anyone suggest how I would go about doing this?

Thanks,
Kristin.


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Dave LaRonde
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:03:11 pm

How do you intend to draw this line? It makes a difference.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kristin Maling
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:08:52 pm

Well, the only method that I personally know for doing this is to import that path I want (designed in Illustrator), then apply the stroke effect to that path (and keyframe the end point). Is there a better way to do this?

Basically, I'm being given a series of storyboards done in Illustrator where I need to have the drawings "draw themselves" or "reveal themselves" (thus, I have all the paths I need, I just need AE to "draw" them).

Is there a better way to do this other than using the stroke effect? The one thing I find when using the stroke effect is that I don't get clean/smooth lines (but rather, the lines are kinda pixelated around the edges).

Any advice one this would be much appreciated!
k.


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Tudor "Ted" Jelescu
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:07:43 pm

Of the top of my head, this is what I would try ( I'm sure there's a better way but I can't think of one now):
Link a light to the path
Animate light so that it matches the timing of the front end of the line as it animates on the path.
Link to the light a disk (layer with a disk made in AE or PSD or AI) that is a gradient from 100% white in the center to 100% black on the edge, with a radius that matches the length of the fade you want for your line.
Render that on a black background (just the disk- light and all other layers turned off). What you get is a matte for the front end of the line. Use that to composite the line on top of the background. Use a Matte chocker to adjust the dimension of the fade.
Anyone else got a more complicated way of doing this???

Tudor "Ted" Jelescu
Senior Compositor/VFX Artist


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Dave LaRonde
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:11:05 pm

If it was done using Write-On, you could parent the brush position property to a smallish comp with a ramp in it, making it a track matte.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kristin Maling
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:20:45 pm

OK, I'll have a look at the Write-on effect.
Would that be one of the better ways for a line-drawing to "reveal itself"?


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Dave LaRonde
Re: Feather the end of a line that draws along a path?
on Dec 21, 2010 at 10:40:33 pm

Oh, I think so. If you take some precautions, I think it will be fine.

Prepare the Illustrator document in the aspect ratio you need to deliver. If it's 16x9, make the Illustrator document 1920x1080 pixels. If it's 4x3, make it 720x540 pixels. Make each path a separate layer in Illustrator; it could get cumbersome if you're not used to it.
Import the Illustrator document into AE so you get your paths in the right place on screen.
Make an AE comp in the same H&V resolution as the Illustrator document.

You can then apply each path to its own sold by using Write-On's Brush position property. You can then make a smallish white to black image with a ramp on it. It's used as a track matte for the solid. When you parent it to the solid's Brush position, the line created when you animate the Write-on will feather at the point of the brush.

A little tweaking -- and a bunch of layers later -- you should be good to go. It's not very automatic, but it works.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kristin Maling
Re: Feather the end of a line that draws along a path?
on Dec 22, 2010 at 2:03:02 pm

Thanks! I'll give that a go today!!!


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Kristin Maling
Re: Feather the end of a line that draws along a path?
on Dec 22, 2010 at 2:41:39 pm

OK, I just tried to do a quick test with this and I'm unsure how to apply each path to the solid's Brush position property (using the write-on effect)? Here's what I did:

- created an Illustrator file (following the "Preparing and importing Illustrator files" doc from Adobe — ie. created the file using one of the Video and Film presets (same size as my comp), set file to "Create PDF Compatible file", set file to "Preserve Paths", saved as .ai file, etc.)
- imported .ai file into AE CS5 as Composition
- created a new comp at my working size (same as .ai file I imported)
- created a new solid within the comp
- applied the Write-On effect to the solid

And that's where I got stuck — I'm unsure how to access the paths within the imported .ai file and then apply it to the solid's Write-On Brush property? I had assumed I'd just be able to select the path, copy it, and paste it into the Brush Position property (via the Write-On effect applied to the solid I created), but again, I could be wrong on how to go about this step?

Any further advice would be much appreciated!

Thanks,
Kristin.


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Matthew Woods
Re: Feather the end of a line that draws along a path?
on Dec 22, 2010 at 7:58:43 pm

Why not use something like CC wide time, or CC force motion blur to add a little bit of motion blur to the effect? That should give you the effect of a feathered leading edge to the line.

-Matt

Need a quick break from motion graphics?
Try my game Constellation at:
http://www.paperdragongames.com


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Matthew Woods
Re: Feather the end of a line that draws along a path?
on Dec 22, 2010 at 8:22:49 pm

Another thought,
instead of using the Stroke effect, you could try using the Vegas effect with one segment, animating the length property. You will probably have to animate the Mid-Point position and opacity too. Adjust the hardness to taste.

-Matt

Need a quick break from motion graphics?
Try my game Constellation at:
http://www.paperdragongames.com


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