Published : 7th October 2003
First off, let me extend an advanced thank you to all of you on the HD list. I think more than any other one, this forum has sometimes been a bit of a one way street for film oriented DP's like myself seeking information about this "newfangled" medium of HD. I'm now about to jump into the HD world, so I hope to be able to share some future insights down the road, but for the time being I remain in the dark ages.
Generally, my questions pertain to the Varicam and its value as a tool for gathering images for compositing.
Let me give you the specifics :
I'm shooting a single-camera half-hour presentation pilot.
The directors/producers need to shoot this on HD with the new P+S Technik (for 2/3" chip cameras) on the front of the Panasonic Varicam. The Varicam (as well as the P+S Technik) is coming to us free, so we're pretty much locked into that camera (as opposed to the Cine Alta, thought I don't think that's an issue here since my concerns would be the same for either camera).
Those concerns are primarily related to the five or six special effects shots that we need to shoot. As it stands now they will be composited on a "Combustion" system, and they range from green screen compositing to a morphing shot. And here's the kicker...there's no money to record to D5 for those shots as most other productions have done when needing to composite. This is a very low budget production, shot over four days, with the SFX work being spread out all over those days, almost all of it on location in New York City.
So here are my questions :
Do you think we're going to be royally screwed if we try to do this post work from the DVCPROHD compressed images?! Are we never going to be able to pull clean mattes without recording to D5? Or will it just be a matter of making it a nightmare for the post folks, yet they will still be able to successfully create the effects? Also, what frame rate would you recommend shooting for these effects (knowing that we will probably shoot the rest of the show at 24P)?
Thanks VERY much in advance.
DP - NYC
We are able to pull acceptable keys from the DVCPro HD tapes for television; we usually do this in Smoke, but the tool set in Combustion is virtually the same. We also use Combustion, but our Compositor is more practiced in Smoke.
Please bear in mind that we do not finish in HD; currently all our post is SD mastered to Digital Betacam. Also, I would hasten to add that we do not attempt really tough keys with this format; no smoke, glass, etc.
Of course, "acceptable," is the real joker in the deck; what's ok for a corporate video or short shots in a local commercial may not be ok for your use. I strongly urge you to consider getting a D5 for the mattes.
I'm quite sure everyone on the list will urge you to shoot some test shots first. I'm frankly quite concerned about what will happen to green screen scenes shot with the P+S Technik.
As for frame rates, we always shoot our green screen FG material at 30 fps; you could always shoot at 24 fps, remove the pull-down with Cinema Tools, and then composite, but if there is a lot of movement, the added blur of longer shutter could also cause problems. Blurs are hard to key.
One more thing, we add green in the camera's color corrector menu when shooting the FG.
>"One more thing, we add green in the camera's color corrector menu >when shooting the FG."
What exactly do you mean by this? Wouldn't the addition of green (in the camera overall) tend to pollute the FG itself, making it "more" difficult to key?
I'm curious about this because we usually do what would ostensibly seem to be the opposite. We generally add plus green to the lights illuminating the green screen only, or in the case of bluescreen work, we tend to add half blue to the background. With bluescreen, we've had very good luck further isolating the key by using 103 or some light warming gel on the FG object's backlight. Unfortunately, the logical counterpart for greenscreen would be some form of light magenta on the backlight, which isn't very realistic, at least on planet Earth.
Finally, we've had good experience keying from HD DVCPro tapes with the Ultimatte plug-in for HD, even at 24 frames, but frankly, most of our HD compositing has been done with fairly sedentary FG's. I will give the 30 frame rate a test soon though. Thanks for the suggestion. Looking forward to seeing you at NAB to compare notes.
South Coast Film and Video
I'm referring to boosting the green saturation in the color correction menu.
This does not seem to cause a problem of increasing the green in flesh tone because there is so little green there to begin with.
I do plan to do some more testing, and I'll let you know the results.
>Finally, we've had good experience keying from HD DVCPro tapes with >the Ultimatte plug-in for HD, even at 24 frames, but frankly, most of our >HD compositing has been done with fairly sedentary FG's.
A minor correction: the Ultimatte AdvantEdge plugin is not SD or HD; it is truly resolution agnostic on any platform.
If your capture hardware and underlying editing or compositing program can support a given resolution, the AdvantEdge plugin will work with it.
HD Ultimatte® now available
>I'm referring to boosting the green saturation in the color correction >menu. This does not seem to cause a problem of increasing the green >in flesh tone because there is so little green there to begin with.
Using masking on any camera when shooting color screens for compositing is not, in general, a good idea.
It is remarkably easy to adjust the masking in such a way that it looks pleasing to the eye but generates technically non-existent colors (colors which fall outside the color triangle).
The upshot is that it will generate a lovely collared edge on your foreground objects where they meet the screen which almost all compositing software will leave unmolested, assuming it to be a part of the foreground image.
Bob Kertesz wrote :
>A minor correction : the Ultimatte AdvantEdge plugin is not SD or HD; it >is truly resolution agnostic on any platform. If your capture hardware and >underlying editing or compositing program can support a given >resolution, the AdvantEdge plugin will work with it."
Sorry for the confusion, but when we tried to purchase the Ultimatte AdvantEdge plug-in for our Boxx HD edit system, it was not available for the system's edit interface, SpeedRazor. In other words, even though our capture hardware and underlying editing program did support HD resolution, there was no Ultimatte AdvantEdge plugin being made for it. Since we needed an "Ultimatte plug-in for HD", we had to get the AdvantEdge plug-in for AfterFX instead, which WAS being supported.
So yes, the Ultimatte AdvantEdge plugin is not SD or HD and is truly resolution agnostic on any platform, but this would not seem to be the case with all Ultimatte plug-ins, at least to my knowledge. Or am I missing something?
South Coast Film and Video
>Sorry for the confusion, but when we tried to purchase the Ultimatte >AdvantEdge plug-in for our Boxx HD edit system, it was not available for >the system's edit interface, SpeedRazor.
That's correct. There are a number of underlying editing or compositing applications the AdvantEdge plugin supports, but Speed Razor is not on that list. The full list of supported programs can be found on my web site.
The older Ultimatte plugin did have Speed Razor support, but it was decided to drop it for the current release.
I've done quite a bit of compositing with Varicam footage, and here a couple of notes for you :
1) Your post people will not have problems with mattes. Sure, it won't be as clean as 2K files scanned off a Spirit from 35mm, but post artists have been pulling reasonable keys with NTSC for years. So, DVCPRO HD won't be that big a problem.
2) If you're using AdvantEdge and Combustion, do NOT use the OS-X version. It's insanely buggy, or at least it was as of January, which is the last time we tried to use it. We had to composite about 100 VFX shots for an upcoming HD-originated miniseries. The main keying tools we used were AdvantEdge on Combustion/WinXP, and The Foundry's Keylight 2.0 on Avid DS|HD.
To be honest, I really don't know if the bugs were because of Ultimatte or Combustion, but either way, it was buggy enough as to be unusable on OS-X in a tight deadline environment.
3) Do not overly backlight your shots. If the foreground edges are blown out to white, there is a magenta ringing introduced at the very edges of the foreground that is really hard to deal with, especially on hair and other thin-edge images. It was the 80/20 rule for us. Most of the keys pulled wonderfully, and we spent 80% of our time dealing with that damned magenta ringing.
Hope this helps,