Greenscreen DV50 or HD & Green Screen Size

[planetearth]

Hi there,

About to go into full prep on a series. Have been shooting on the DVX, but don't want to use the DV25 codec for greenscreen for I hear DV50 is much better due to colour space. So, even though I am patiently waiting on a Red, looks like I will need to buy a HVX200 in the mean time to fill the gap.

I will be shooting 2 cameras for the duration of the shoot, so perhaps I use my DVX as one and the HVX200 as the other in DV25 and then only the Greenscreen in DV50, but that mixture could be a pain in post. If I go DV50 or HD720 for the whole thing, was thinking of buying one HVX and renting a second.

Have read many post on shooting DV50 and HD1080 being the best 2 options for shooting the greenscreen, but thought I'd solicite opinions on if I should shoot the whole project on DV50 or HD - any thoughts, suggestions, opinions (I.E. should I shoot only 24pa to avoid interlaced)??? It is not intended for an HD release.

Also, there will be a number of greenscreen shots where I will need 2 kids riding bikes - any suggestions on what size of greenscreen I should get (height and width).

I have also read many posts on Green screening tips, but was wondering if anyone would like to add tips, suggestions and/or what brand of greenscreen you have used successfully.

Cheers,
Dale

[Jim Arthurs]

If you have absolutely no need for HD, then shoot DVCPRO 50. Lighter compression = better key in any situation where the screen lighting is less than perfect.

Shoot progressive if at all possible. Don't shoot 720p against green screen unless you have to; DVCPRO 50 and the 1080 give better results, all things being equal.

Size of screen.... are the kids side by side, or one after the other in a side shot? You want the screen as far back as possible, so you can light it independant of the foreground subject. That is, unless you need to see ground contact and your angle is high looking down, in which case your best bet is to paint a cyc in a studio.

Best paint is Composite Components...

http://www.digitalgreenscreen.com/

Best fabric is any nylon backed material. The above company carries it, but this stuff is good too...

http://www.eefx.com/eefx2/store/item_ck_bk.html

Regards,

Jim Arthurs

[planetearth]

Thank you for the concise info Jim. Yes, the kids will be side by side. I will try to give some distance from the screen and shoot long lens. So with that in mind, how big a piece of material do you think if i do a two shot. Would like the material option to avoide a location move and use one of the existing locations.

[Spartacus]

Don't shoot 720p against green screen unless you have to; DVCPRO 50 and the 1080 give better results, all things being equal.
Could you elaborate on that some more, please?

[Jim Arthurs]

10' by 16' should cover this and most future needs. If it's a long lens, the framing is such that you don't see ground contact and they're overlapping in frame, you could get by with 5' by 10'...

I suggest taking some bikes and going out with your DVX and lining the shot up against a wall and experiment with how far away you can be for the smallest screen size...

Jim A.

[Jim Arthurs]

Could you elaborate on that some more, please?

Here's a web page I put together...

http://www.imageshoppe.com/HVX_bluescreen2.html

720 works, but 1080 gives you greater bandwidth per frame in addition to a slight horizontal resolution bump. What works great, is to shoot your green screen element with -3 detail at 1080 and then scale it down into a normally shot 720 background. Add a bit of sharpness if necessary to the FG element, but they are a good match.

Jim Arthurs

[planetearth]

Thanks Jim, I've actually seen that site before - good work and good info. Think I'll get some of that eefx screen.

Most appreciated,
Dale

[Spartacus]

Here's a web page I put together...

http://www.imageshoppe.com/HVX_bluescreen2.html

720 works, but 1080 gives you greater bandwidth per frame in addition to a slight horizontal resolution bump. What works great, is to shoot your green screen element with -3 detail at 1080 and then scale it down into a normally shot 720 background. Add a bit of sharpness if necessary to the FG element, but they are a good match.

Jim Arthurs


i´ll have a look into that soon...
Thanks a lot!

[DCSensui]

I posted this elsewhere in these forums. But just in case, here's a sample of what we did with an HVX200.

Shot at 1080p30. EEFX.com greenscreen material, lighted with two Lowel Tota Lights exposed at 60 IRE (used the zebras in the HVX to establish even exposure).

720p hasn't been tested yet but it would be a nice option for slow-motion work. In this case I shot at 30 FPS with a shutter speed of 1/120 and slowed it down via software in After Effects.

Edited in Final Cut Pro. Expoted to AE with Automatic Duck. Keying and compositing was done with After Effects with Keylight. Just one click and it was nearly perfectly keyed. Just some tweaking and it was done. Even held the hair.

I had motion trackers on the background but the composite was getting busy enough so I opted to leave it untracked. The trackers are just ordinary Post-It notes.

Converted to SD for broadcast with AE, then mastered to Betacam SP.

Windows version:
http://imaginationhawaii.com/videos/noa_noa_pvo.wmv

Quicktime version:
http://imaginationhawaii.com/videos/noa_noa_pvo.mov

Original rough cut with demo audio; green screen:
http://imaginationhawaii.com/videos/noa_noa_green.mov

[Spartacus]

So any advantages to use 1080p over DV50 if the final output is SD?
Like increased resolution? (I read "yes" before, what are your observations...?)

[DCSensui]

So any advantages to use 1080p over DV50 if the final output is SD?
Like increased resolution? (I read "yes" before, what are your observations...?)

The increased resolution has two advantages in tests I did.

-- More detail in the chroma channels to provide a more accurate key.

-- More pixels to allow more accurate motion tracking.

Disadvantage: Longer render times. It took an hour to render the visuals for this 15-second spot. Ran it on a 2.5 GHz G5 Mac.

[Jim Arthurs]

When I did the tests back in May, we shot the same subject in DV50, 720, 1080 and both 720 and 1080 uncompressed.

I like the increased resolution of 720 and 1080 for motion tracking, but as for keying, I believe DV50 is a bit cleaner due to the lighter compression. As far as visible detail, the SD stuff seemed to carry almost everything that the HD did in terms of fine hair, etc.

Now, the moment you start to STRESS the shot, with screen illumination that is off a bit, or un-even lighting, the DV50 will really start to out-perform the HD stuff if you need to haul on the mattes. Both 720 and 1080 reveal a "window-screen" effect to the matte caused by the codec, this is a fixed pattern, detected as "notches" cut into the edges of your matte. Greyscale areas such as semi-transparent hair will degade quickly, and almost always show this pattern. Here is the case where uncompressed was superior to DVCPRO in any flavor.

Just some observations....

[Spartacus]

Thanks guys!

[Lill Creates:]

FWIW, a varicam shooter told me it's all about the color space. sure it's 4:2:2 in 50, but with HD resolution available, there's so much more information to attach to the image.

garbage in, garbage out is the basis i think. not that 50 is garbage (it rocks), it's just that the HD is that much sweeter.