Greenscreen Help !!! Please !!!

T

TEXAS VIDEO GUY

Active member
i have 3 - 500 watt lights on tripod stands, and a 300 watt light in the main socket, and a few lamps from around the house that i could use if i need to ...

im shooting on the hvx 200 in sd (thats 480i right ?), and using 24p

8 ft X 22 ft greenscreen with a subject thats pretty much standing still about 5 - 7 feet away from the greenscreen, i dont have a problem with the subject casting shadows, but i think im getting 2 big hotspots, and its in my garage so room is seriously limited, and ive tried a bunch of different placements for the lights, so far i havent come up with anything even decent, do i need to change from 24p ? or is there a trick im missing ? the greenscreen looks evenly lit to me on and off camera

are there any scene file settings that i should try for this ... ive only had my hvx since monday, ive shot 3 times on it for an hour each (a tape), so far, 2 were with the greenscreen (about 20 minutes each time)

i dont have the hvx book or dvds yet, and i wont be getting p2s until the 16gbs are available

thanks
 
and im using vegas 6 to do the keying, but i have premiere pro 2 and after effects cs2 and access to cs3, ive only used vegas before though ... do the other programs key better ?
 
Successful greenscreening is a combination of things.
#1 is a proper backdrop
http://www.eefx.com/index.html
#2 - Lighting is everything - I don't think 3 - 500 watt lights
are going to cut it.....
You might need at the least - 2 1K lights to light just the backdrop
and then another 1K softbox to light your subject. And some
reflector boards to fill in some of the shadows.
And then it really helps to have a backlight on your subject as well.
#3 - Software - The keyers in editing programs are not very powerful.
I use Keylight in After Effects - Shake in FCP is good - steep learning
curve.
Here is a site where I do the shooting and editing.

http://www.sitevid.com

Good Luck
 
Press the Zebra button on the side of the camera three times to turn on the marker. When the marker is on, you will have a percent readout that you can point at various locations on your green screen and it will help you determine how evenly lit the screen is. This is much more accurate than trying to guess it with your eyes. And you'll be able to tell where the intensity changes and by how much.

It's not the brightness of the green that matters -- it's more the consistency. So a mild green color is okay and has less chance of bouncing back onto the subject. It is common to overlight the background which causes spill that is hard to key out.

Remember to move the lights back and make use of the inverse square rule to control overall brightness. Sometimes it works well to move the lights back and to the sides so that only the softer ring of the side of the light strikes behind the subject, and the brighter center spot is actually nearly off screen to the side. Softer less directional lights are better for the green screen (for me). And I try to avoid any of the screen light hitting the subject. Then I illuminate the subject with a soft reflector light separately.

If it is 22 feet wide and the subject will be nearly still, you might want to optimize only the area around the subject rather than trying to light the whole thing. You can use a garbage mask in post to remove much of the surrounding area before you key the remainder. You might try reflectors or even replacing the lights with broader floods to reduce the hot spots.

Oh ... 24pA ... you will want to remove the pulldown prior to compositing. You don't want to key over those interlaced frames.

Good luck!
 
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"you will want to remove the pulldown prior to compositing" ... whats that and how do i do that, and ya i mentioned that the subject wouldnt be moving much in hopes of getting a response like urs, i dont have broader floods, and whats the inverse square rule ? and is keylight something included in aecs2 or aecs3 ? or is it something extra i have to purchase ? right now im stuck with what i got ..., thanks yall
 
Um... you have a pretty significant learning curve ahead of you.

First, the HVX records in 13 different formats. Several of these formats are better for keying than standard definition DV. Unfortunately, it does not record in these modes to miniDV tape -- only to P2 cards or perhaps directly to your computer over firewire if your editing program supports that.

The camera can record in HD, which has much more resolution than SD and enables you to hide the compositing artifacts better. Additionally, it records in the DVCPRO50 codec and the DVCPROHD codec which have double the color space of DV and are much more suited for keying.

In tape mode, your camera only records in SD and in the DV codec with 4:1:1 color. When recording to tape, you have a choice of formats: 60i, 30p, 24p, and 24pA. "i" stands for interlaced. "p" stands for progressive. Interlacing is a standard television method in which every other line in each frame is grouped into a field. The odd lines form one field and the even lines form another field, and each field is alternately recorded. This gives a sharp look to the video but it is not great for keying. Progressive mode records all of the lines in order. So it is a better choice for keying.

Standard video is recorded to miniDV tape at 30 frames (60 fields) per second. Film plays at 24 frames per second. To get the film look on video, your camera records 24 frames, just like a film camera. But to record that to tape it has to fill in the missing 6 frames to conform it to 30 frames per second. The "24p" and the "24pA" are different methods to top up the 24 frames to 30 so that it can be recorded to tape. These extra frames are called "pulldown". And removing them to get back to the original 24 frames is called "pulldown removal" or "Reverse Telecine". This is a big and complicated topic and you should read about it online and in the HVX book when it arrives. If you are working in SD video, at 60i, then the best choice for keying would be 30p which can be edited on the same timeline in your editing program and gives you full progressive frames.

Keylight is a professional keying plug-in effect that is included in some versions of After Effects.
 
Greenscreen

Greenscreen

Ok, now first let me admit that I have never shot greenscreen on DV. I have shot it hundreds of times on 35mm and S16mm, so take everything I say with a grain of salt.

First off, Light the screen evenly. I typically gel my lights (for the screen) with 1/4 CTB to help the green pop. I would also use a light meter (regardless of digital or film), first I would use it to make sure the screen is lit properly. Then I would use it to check the stop ratios between the subject and the screen. The rule of thumb when shooting greenscreen is that the Screen should always be no more then 1/2 stop to 1 stop brighter the the Subjects Key light. If we were shooting Film the optimal stop for Gscreen is 5.6 with a 4 - 4 1/2 on the subject (which is irrelevent for DIGI). Next I would do my damnedest to use props or set pieces to place in the foreground and back ground to create depth. Do not worry about the distance between the subject and the screen, another rule of thumb when lighting greenscreen IS TO ALWAYS BACKLIGHT THE SUBJECT. This will help with the seperation between the screen and the subject, and to get rid of the Green reflection on the subject you simply use 1/4 or 1/2 magenta on the backlight to help negate the green.

Well I hope that helps, and remember I am coming from a film background so someone might say otherwise. But I have lit tons of greenscreen, and if I were gonna light for Digi, I would do the same thing.
 
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