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Blur and alpha issue

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groslaine

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  • Real Name: lecointre leny

Blur and alpha issue

PostThu May 12, 2022 10:29 am

Hi,
I have a project where I animate a fake shadow.
My issue is ; there is a "limit" at the end (outside edge) of the shadow that is visible.
I dont know if its because I use an alpha divide, or is it the blur ?
I try to put the blur after the alpha divide but the problem is the same.
What would be the solution ?
Thx

capture fusion.jpg
Shadow blur
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groslaine

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Re: Blur and alpha issue

PostThu May 12, 2022 12:03 pm

I try to change the alpha divide by a merge, matte control or channel booleans and the issue is the same. Maybe the blur node is the issue ?
edge issue.png
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Sander de Regt

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Re: Blur and alpha issue

PostThu May 12, 2022 4:02 pm

Are all the things on the underlay masks?
In that case they're not really images in a way. So using a blur (which is meant for actual images) will probably give unexpected results. I don't know what the alpha divide is doing there either for the same reason.

Can you walk us through the setup and explain what part is trying to achieve what?
Because every seperate mask has its own blur settings as well, so I'm not sure what you're trying to blur and with what purpose. What is the rectangle mask doing there in combination with the bitmap mask etc
I'm just a bit confused.
Sander de Regt

ShadowMaker SdR
The Netherlands
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groslaine

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Re: Blur and alpha issue

PostThu May 12, 2022 5:06 pm

It was not a bad idea to "blur" with the soft edge of the roto mask. I tried, but it didnt work. The same "sharp" edge effect append.

To explain my workflow ;
- In the underlay I have my roto (polygon mask for the body)
- The blur to blur the all roto mask
- AlphaDivide (or merge or matte control) to extract the black shape of the roto and have it on transparency.
- Then I put this shape on top of the background video with a merge.

(- the rectangle shape is just to mask the shape, ignore it)

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