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Old August 6th, 2007, 03:09 AM   #1
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DV and Reflecmedia Chromatte, help!

Hello,

I am no expert at lighting or chroma key and was wondering if anyone had used the same, or at least a similar system to me and could give me a pointer or two.

I understand the fundamental problems with Chroma Key and DV, however.

I have got Reflecmedia Chromatte (http://www.reflecmedia.com/content.a...=chromatte.htm) setup with the (Green) LED light ring on our Sony DSR-250P camera.

It then feeds straight into the back of my mac into Final Cut Pro via firewire.

I've done some tests, and all I can come up with is half the background keyed out and blocky green bits around the talent.

I have to shoot 180 people, so I want to get it right before I start, and I need the key to be really simple in either Final Cut Pro or After Effects.

Any suggestions? Is the only answer using a Sony HD camera? (I could maybe get my hands on one).

Thank you
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Old August 7th, 2007, 02:26 AM   #2
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Hmm...I'm not sure what you're doing wrong. I recently did a test with this Reflecmedia setup and it keyed immediately and perfectly. I used a keyer in Motion, so you may want to try that, too.

I was very impressed by the results of Reflecmedia. We shot again with it recently, but haven't keyed it yet. I'll try to report back soon after.

Kevin
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Old August 7th, 2007, 03:08 AM   #3
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Hmm...I'm not sure what you're doing wrong. I recently did a test with this Reflecmedia setup and it keyed immediately and perfectly. I used a keyer in Motion, so you may want to try that, too.

I was very impressed by the results of Reflecmedia. We shot again with it recently, but haven't keyed it yet. I'll try to report back soon after.

Kevin
Thanks Kevin,

Are you using any lights? Or just ambient lights?

How far was your camera from the screen, then the talent from the screen?

Thank you!
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Old August 7th, 2007, 04:01 AM   #4
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I've done some tests, and all I can come up with is half the background keyed out and blocky green bits around the talent.
Hi, I've owned my Chromaflex kit for over 3 years now, and use it for doing talking head interviews at clients' premises. I started out with a PD150 and now use a Z1 shooting in HDV for later downsampling (more about that in a moment).

The trick is to put the talent AS CLOSE to the background as possible to minimise shadows from the LED up front. This is totally contrary to traditional chromakey setups (and due to the lack of space in most locations, a major Chromaflex strength).

Secondly, light the talent FIRST (back light can be tricky) with the LEDs off, and set your exposure manually. Then (and only then) wind up the LEDs to about 7-9 (YMMV). If anything's in auto, you'll end up underexposing the talent, so ensure everything's in manual. If you can't back up enough from the talent, you may need quite a bit of light to ensure any shadows in clothing don't 'fill' with the LED glow.

I've pulled some great keys from it, mainly by avoiding the FCP chromakeyer completely.

My quickest method is to use the zMatte plug-in, which includes some chroma smoothing to remove the blockiness of the edges which is all part of the DV chromakey experience. This will do for business shoots where hair and fine detail isn't so much of a problem.

For truly great keys (I've had some that was assumed DigiBeta), I work with HDV footage in AIC (now ProRez 422) and either key using KeyLight in AfterEffects or zMatte in Final Cut Pro, then downsample the result to standard definition using a 4:2:2 codec like DVCPro50.

I've tried DVmatte Pro and whilst possibly pulling a better key from DV by using luminance info, I found it fiddlier to use and much longer to render. The new iteration of zMatte has got a great chroma resampler which evens things up a little.

Watch out for glasses and other reflective stuff, though!
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Old August 7th, 2007, 06:53 PM   #5
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Thanks for the detailed response Matt.

I hope the camera, talent setup will help me achieve better keying.

But as you said, DV has the horrible blocky key.

I am trying to borrow a Sony HDV 1080i 3CMOS HANDYCAM HDRFX7, which should help solve everything.

I can't afford to buy any more software, so I'll have to use the basic keying in FCP, After Effects, or Motion. I'll avoid FCP as you recommended.

Thanks again, I'll let you know how I go.
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Old August 8th, 2007, 03:20 AM   #6
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I am trying to borrow a Sony HDV 1080i 3CMOS HANDYCAM HDRFX7, which should help solve everything.
Simply doing all your work in HD and scaling down afterwards will partly help, but the devil's in the details - or edges in this case.

In addition, I'd ingest your HDV rushes using AIC or ProRez, do a pre-edit of the material so one's only working with good takes, then use the AfterEffects KeyLight keyer.
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Old August 8th, 2007, 06:12 AM   #7
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Damn these edges.

Do you think it will work without buying any more software?

Are the edges going to drive me over the edge?

I have FCP, AE CS3, and Motion 3.
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Old August 9th, 2007, 02:46 AM   #8
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I just had a really good test.

With the talent on a stool against the 'green' screen, with manual camera focus and using After Effects with Key Light and Colour Key got a 88% key!

It's just the edges around the body that annoys me. Like you said, the detail is in the edges.

I am hoping HD camera, and HD footage will reduce that.
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Old August 10th, 2007, 10:31 AM   #9
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It's just the edges around the body that annoys me. Like you said, the detail is in the edges.
The pay-for plugins add information from the luminance channel to fill in the blocky edges.

Don't forget to do garbage mattes to cut down on the work the keyer has to do (or rather, don't waste its time with variations in the background). Compositing is a profession in its own right, and you may have noticed the dark fringes that can develop around your subject if its not close enough to the background - this can be a real bugger to correct.

For a bit of fun, I've found a quick intro slide preso I did for our local Final Cut Pro user group back in late 2004:

http://www.mdma.tv/movies/chromakey.mov

Takes a bit of time to appear (3.9 Mb and it doesn't progressively download). Click the movie to advance the slides - and yes, the 'bump' was a bug due to Sorenson 3 Pro... Plus one couldn't record narration... Which is why we don't see this sort of thing very much!
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