Green screen settings help

[Lenilenapi]

i have a shoot next week where we need to shoot a talking head green screen and also some documentary footage of a race.
We're shooting HVX to P2 cards.

I had advised the client to shoot 720 24PN or 30PN for all of it , but now I'm seeing posts that seems to suggest shooting the Green screen at 1080, which I have actually never done.
Shooting the doc material @ 1080 sounds like it will be very intensive on the P2 cards though.

1. My idea now is to shoot the doc stuff ( of a bike race) at 720/30PN or 24PN and then shoot the green screen at 1080 60i/30P or 24P (? I could also shoot it all at 1080 60i .)
Finally then downrez the green screen after it is composited so in the end all the HD is in 720 30P.
How hard is downrezzing?

2. How bad is 720 30PN for green screen, do you really need 1080?

3. What kind of 1080 will give me the best green screen -60 i or 30P?

 

[NeverColdCall]

My HVX just came in and since all of my stuff is talking head green screen I'm going to test out the different settings tomorrow and see what works best.

Just to fire up the cam and try it out I shot some random footage of myself in front of the screen at 720/30p and it keyed VERY nicely!!

 

[andy_starbuck]

I ran tests in 1080i24p and compared it to 720p24pN several months ago. After compositing and downsizing using compressor, the 1080 original showed high frequency detail more clearly. I had an actress fluffing her hair, and the 1080 showed more detail in the hair and in her complexion. I decided to shoot in 1080, downsize in compressor batch, and do my compositing in 720 unless I needed the extra detail or had a bad key where I needed to hide more artifacts with the extra resolution.