Sky mask

[Simon Denny]

For the life of me i cant get this to work. (or i have forgot)
I have footage of a bridge on a dark grey day and the sky is very grey.
What i want to do is lay a picture of a blue sky under the bridge footage.
I guess as a mask?

Can anyone help

[Don Bloom]

Pan/Crop>Bezier mask
Put background footage on track 2 below the bridge.

Don

[Simon Denny]

Yeah thats what i thought but i cant get the thing to work.

Track 1= original footage
Track 2= sky footage.
Both source alpha

[Simon Denny]

I dont think it will work as i'm panning right to left on the bridge and to Bezier mask the thing would take forever and not worth it.
If the bridge was static no problem.
I really need one massive green screen over the bridge........

Oh well

[Steven Bills]

Can't you just key out the gray background, and then place the sky image under track #1, as stated earlier?

Just a thought.

SB

[Simon Denny]

Yeah, that sounds like it but which effect do i use to key out the background?

This is what i have done and it looks a bit crap.
Copy the footage twice.
Track 1= original footage/ multiply mask/Levels increased a bit
Track 2= original footage/ sony invert fx, blend amount 1.000/ sony Chroma Keyer, pick sky color from screen, blur amount 0.600 to get rid of some nasty's
Track 3= new sky photo.

Render time was 12min @ 22MB for a MPEG 2, very long for 30sec clip.
Anyway it was a good test. MUST BE A BETTER WAY?

[Douglas Spotted Eagle]

Will secondary color correction work?

[Simon Denny]

Yeah secondary color correction works fine, i thought keying might be easier as in the grey sky is a lot of white cloud.

Cheers
Simon