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City Lights & Other Shaders Hiding Background

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Cowsgomooooooooo
Posts: 31
Joined: Thu Dec 16, 2021 8:05 pm

City Lights & Other Shaders Hiding Background

Post by Cowsgomooooooooo »

Hello,

Still can't figure this one out. There are a few shader effects in which I have a video feed of a top layer incoming from direct video source that is chromekeyed out.

I'll also have a background behind it working just fine.

However if I use city lights on the layer above, the input video, the layer behind is no longer viewable. Any way to alleviate this that the city lights shader for example only affects the used pixels and not affecting the applied alpha on that layer? So the background will still show up behind.
Sadler
Posts: 1139
Joined: Sat Aug 02, 2014 7:10 pm
Location: London, UK

Re: City Lights & Other Shaders Hiding Background

Post by Sadler »

Mask the FX with the keyed source.
Cowsgomooooooooo
Posts: 31
Joined: Thu Dec 16, 2021 8:05 pm

Re: City Lights & Other Shaders Hiding Background

Post by Cowsgomooooooooo »

If I'm not confused.

I created a 'mask' layer. I put the source video on top of the 'background' effects at the end of the node chain.

This causes the 'source video' to be affected by the background coloring and effects, and all the alpha around the input source remains black.

For example:

https://i.gyazo.com/f67e984eee1038c9d6d ... 1d66fc.mp4

The 'dot matrix' which is the background is only applying to the source pixel color channels. Only want it to apply to the black / alpha channels so it can operate behind the source. Basically the opposite. Only after applying city lights causes this issue (i'm assuming it affects everything not just color channels). Is there another part in the chain of mask would need to be applied?
Sadler
Posts: 1139
Joined: Sat Aug 02, 2014 7:10 pm
Location: London, UK

Re: City Lights & Other Shaders Hiding Background

Post by Sadler »

Screenshot 2021-12-26 082453.png
Screenshot 2021-12-26 082453.png (37.94 KiB) Viewed 2914 times
Cowsgomooooooooo
Posts: 31
Joined: Thu Dec 16, 2021 8:05 pm

Re: City Lights & Other Shaders Hiding Background

Post by Cowsgomooooooooo »

This works, kind of. But does not achieve the result of just having a foreground over a background. Maybe it's the limitation of the City Lights shader? I've noticed more than one does this sort of thing, so was wodnering a general world around.

Using this method, didn't seem to have an affect, until I added .5 alhpa to colorHSB in keyframe chain. But even then, the layers were blended together, rather than the key frame just being over top of the background layer.
Sadler
Posts: 1139
Joined: Sat Aug 02, 2014 7:10 pm
Location: London, UK

Re: City Lights & Other Shaders Hiding Background

Post by Sadler »

Sounds like you are creating a poor chromakey or no key at all. Use Terry Payman's tip to view your keyed source alpha mask using the RGB Swap module. Terry also graciously provided a module called Chroma Mask TP which as well as providing a good set of tools for keying, also has an option to view the alpha.

If you can't figure it out yourself, post a single frame of your source footage here and perhaps we can figure out how to get a better key.
Cowsgomooooooooo
Posts: 31
Joined: Thu Dec 16, 2021 8:05 pm

Re: City Lights & Other Shaders Hiding Background

Post by Cowsgomooooooooo »

I'll look into it when I get home. Thank you. The program I use is actually sending it without a chromakey needed, just my avatar and alpha around it. When I realized this I still got the same result sadly.
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