Overlay Fireworks
 

Trying to overlay fireworks, I.E. one track has some fireworks but not a lot so want to overlay another track that has more fireworks end result lots of fireworks...

Tried parenting the top track and child the second and found "add" on the top track works good except when both tracks have something in the same area.... when this happens get ugly green/black etc. blobs of color...

Open to suggestions!

Hi Thomas,

Can you just increase the opacity on the top track to about 50%? I think that would allow a combo of the two events to be seen.

Is the background of the fireworks black? If yes, I'd try putting the fireworks on the top track and just chroma-key out the black. Then the lower track would show through behind the fireworks.

Thanks, tried lowering the opacity and it obviiously dimmed the fireworks in that track...

Edward, thanks for the reply, both tracks contain fireworks with black backgrounds, I'm trying to merge the two together to make "more fireworks visible...

If you follow Edward's advice, you should get that. The top track, key out the black you will still see all the fireworks there, but everything else will be transparent. Therefore, all the fireworks in the lower track will be seen where ever there was black in the top track.

Based on what you described, this is the best course of action...

Thanks I'll give this a try tonight, so just to be clear, don't parent/child it - which I think is whats causing the splotches, but just key out the black on the top track?

Thanks again!

I think adding two overlapping colors is what is causing the splotches. But it is hard to tell without seeing a sample frame showing them.

Yea, I'm going to try this tonight when I get home :)

I'll post results and if there are still splotches a short clip...

The parent/child thing I don't think will make a difference. If I understand how that works correctly, it's primarily for transformations; anything done (move/scale/etc) to the parent is also applied to the child.

The Add blending is almost certainly causing your interesting colour problems. In Add mode, each R, G & B component is actually added together for each pixel. So if you had a blue pixel and a red pixel, you'd end up with some kind of purple, blue and yellow would give you white (or close to it). This mode can be useful for overlaying an image that has a black background, as black (in cRGB) is 0:0:0 so it adds nothing to the blended image. But the colours can turn out curious.

Try using Screen (or overlay? not sure what it's called now, away from my VMS machine) as the composite/blend mode.

And yes, just key out the black on the top-most instance of the fireworks.

OK, tried chroma keying the top track - no parent child - and it seems like that is working pretty good:

YouTube - Movie_00_(overlay).mp4

I did try it in a few other spots and saw "some" color bleed so I'll have to watch where I overlay but I don't see any in that clip above...

Split screen of the two tracks for reference:

YouTube - Movie_00_(overlay-split).mp4