Can V5 Chroma Keyer pull a good key or do I need?

Randy Brown wrote on 7/1/2008, 9:52 AM

Yes I know I need to upgrade but just wondering if the V5 Chroma-Keyer is sub-standard.
Here's what I've done after reading this tut on greenscreening but I'm still getting unusable results:
-Covered all windows from bleeding in light.
-Placed 2 softboxes evenly on my wrinkle-free, tightly-stretched green screen (checked for even lighting by opening iris and seeing zebras evenly distributed)
-placed a spot on the subject (dolls) with barndoors preventing spill onto screen
-after placing footage on timeline I applied the chromakeyer (again V5), deselected the check mark, took large screen sample with the eyedropper, selected the checkbox again (to turn on chromakeyer) selected show mask only, then slid high threshold to left until all white subject and low threshold to right until background all black.....or at least tried to do that.
When I slide the high threshold to the left the subject does start getting all white but not before the background starts turning white also. I try to split the difference between the low and high but still crap.
Here's another thing that's maybe worth mentioning: when I use the eyedropper on the greenscreen it looks much darker than what's showing on my external TV monitor. I know the LCD will look darker than a TV but when I select the green screen preset in chromakeyer I get a cleaner key.
I realize there are many factors involved in doing this process but maybe someone has a suggestion??
TIA,
Randy

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JohnnyRoy wrote on 7/2/2008, 12:04 PM

> Anyone have any comments on Serious Magic (pricey but looks muy cool)?

I would recommend Boris FX over Ultra (which as others have stated, you can't buy alone anymore now that Adobe took it over from SM). First of all, Ultra only does keying and for the same price Boris FX does 100x more. The Motion Tracking alone on Boris FX is worth the price but I digress... Second, I find that Boris FX has a better keyer than Ultra. In addition to everything Ultra does, Boris FX has the ability to wrap the light of the new background around the subject. Any spill that you may have had from the green screen is replaced by spill from the new background. This really "sells" the illusion that the person is really there with the background. Also Boris FX plugs in to Vegas and Ultra is a standalone with it's own set of rendering issues to get media in and out of it. I have both and I never use Ultra anymore.

Having said that... the secret to getting a good key is having good even lighting without any spill in the first place. Light your source with a difference light than the background. Also, when I use the Vegas keyer, I use a combination of Chroma Blur -> Secondary Color Corrector -> Chroma Keyer. The Chroma Blur is set to horizontal only and will eliminate jaggies in the key. I use the secondary color corrector to fix any lighting problems before I try and pull a key.

~jr

Randy Brown wrote on 7/2/2008, 3:41 PM

Well I finally got a clean key (the saturate green with secondary CC got me over the hump).
It still looks a little cheesy with say a landscape background but I know there are many other factors involved to make that believable (lighting angles on the talent etc).
However if a corporate client wants a logo or other graphic in the background I feel comfortable with doing it thanks to you guys.
Thanks again everyone!
Randy

Rory Cooper wrote on 7/2/2008, 10:37 PM

Thanks JohnnyRoy

I haven’t been getting the results I am looking for with Vegas chroma keyer so I will do a couple of runs. Your suggestions will be a real help

I have Boris FX 9 and RED . Your experience with Boris FX is very interesting and have taken it to heart that’s clearly the way to go
Shooting good green key stuff is not easy your suggestion light sources make sense
Could you maybe also use a green gel for the backlight would that make a difference?

Thanks TheHappyFriar

I have seen the options in PI for avi [uncompressed] does it render two separate clips or combined? I see this is new in the upgrade
But haven’t used it yet
Vegas doesn’t recognise the Alpha [ am I correct] so rendering AVI with alpha channel will be ok for BORIS?

Appreciate any advice thanks

TheHappyFriar wrote on 7/3/2008, 5:55 AM

I have seen the options in PI for avi [uncompressed] does it render two separate clips or combined? I see this is new in the upgrade

I've only used PI SE, but when you render an AVI, PNG (think it does PNG's), TGA with Alpha, it saves a normal alpha in the file. When in Vegas you may need to go to the clip properties & change the alpha from "none" to something else, I forget if it autodetects. You may be able to render a separate alpha channel mask file too, I forget.

Randy Brown wrote on 7/3/2008, 6:01 AM

Could you maybe also use a green gel for the backlight would that make a difference?

From the research I've done the in the last couple of days I'm pretty sure the answer is no, not green.
In fact, just the opposite... but hopefully someone that actually knows will clarify.
Randy

logiquem wrote on 7/3/2008, 6:50 AM

1. Forget performance from a dinausauresque P IV for compositing...
2. All you crop in post don't need to be keyed, so you don't have to fight with not so even green background extremities when adjusting the key prameters.
3. I shout my subject just like it will appear in the final composition. No redimension necessary, much better, cleaner results, less rendering time.
4.Chroma blur makes a very big difference for smoothing out your DV footage and avoid using a high blur value in the chromakey fx . I really wonder how this can make no difference in your situation...

Rory Cooper wrote on 7/3/2008, 7:11 AM

It still looks a little cheesy with say a landscape background

There is a trick I was taught when doing artwork and that is always use the dominant background color in your subject matter so the final result will look more real,
Because light refracts .

The same with video. So look at the overall color tone [don’t look at detail squint your eyes, if that makes sense] and bring that color into your forground
In painting it’s called setting your pallet

That’s basically what JohnnyRoy was suggesting with Boris fx color wrap. Makes a lota sense.

Harold Brown wrote on 7/3/2008, 7:28 AM

I recommend keeping the screen 10 feet away.

This video is a Vegas chroma key

I use Zenote DeArtifact to assist with Chroma Key. I like the final look that I get.

Randy Brown wrote on 7/3/2008, 7:45 AM

From logiquem's first post 1: crop anything you don't need on the left, top and right sides
I didn't understand why

From his last post : 2. All you crop in post don't need to be keyed, so you don't have to fight with not so even green background extremities when adjusting the key prameters.
Now I do : )

3. I shoot my subject just like it will appear in the final composition. No redimension necessary, much better, cleaner results, less rendering time.
Didn't think about that...that's gotta make a big difference.

Randy Brown wrote on 7/3/2008, 7:53 AM

Hmmm...I wonder how much of Ed's magic was actually Harold's magic.
Thanks Harold, I'll also check out Zenote DeArtifact.

Rory Cooper wrote on 7/5/2008, 7:44 AM

I tried some bombed footage

Chroma blur[ JohnnyRoy] then secondary color corrector [tutorial from bops] no chroma green key necessary [great combo]

And now the footage is usable

Thanks for the good direction everybody

JohnnyRoy wrote on 7/5/2008, 9:55 AM

> Could you maybe also use a green gel for the backlight would that make a difference?

> In fact, just the opposite... but hopefully someone that actually knows will clarify.

That's correct. If you use a Magenta gel (the opposite of Green) on the backlight it will neutralize the green spill and make the edges of your subject look more natural. Obviously it's best to avoid spill all together by keeping your subject 6+ feet in front of the green screen but in tight quarters (or will small green screens) that isn't always possible.

~jr