Blue/Greenscreening with HDV

[Daniel Broadway]

Hi. I had a question for all you technical guys out there. Do you know if it is easier to key HDV or DV. I wonder if DV compression, or MPEG2 compression of HDV is better suited for chroma keying.

I do alot of blue/greenscreen shots for visual effects, and I was wondering how easy it would be to key HDV with something like primatte. Has anyone tried this?

[Paul St. Denis]

Frederic Haubrich and Darren Kelly have both posted examples of chroma key using JVC HD in this forum.

In theory the camera's 4:2:0 sampling method should be an advantage over DVs 4:1:1 for keying, not because there is more color information (there isn't) but because the chroma information is less spread out than in 4:1:1

If your final output will be DV, downsampling will be an advantage if you use HDV.

I also did some keying and found the chroma noise that the camera produced to be the biggest problem, I think the compression is less problematic. People here are working on methods for cleaning up chroma noise which should help keying with this camera greatly.

I havn't tried primatte, but I would be concerned that it was built for DV and would probably be more effective with 4:1:1 footage.

[Heath McKnight]

Daniel, do a search:

http://www.dvinfo.net/conf/search.php

under HDV and greenscreen, or even Darren Kelly or Frederic Haubrich and you'll find some info.

heath

[Daniel Broadway]

Humm, that is interesting. I wonder if 3CCD HDV camera would have better keying results. In my experience keying DV, it's not so much the compression that hurts the keying.

Edge sharpening and 1CCD cameras are the most problematic cameras to try to key from.

Primatte keys DV footage beautifuly. However, it is not designed for DV. It is designed for high end 35mm film keying and compositing.

[Helen Mets]

Both Primatte & Ultimatte work quite well with HD10, which one to choose depends on footage. As EE is quite low on HD10, it makes things easier as well. HDV seems way better for keying to me.

Also, I got best results by removing chroma noise first and then keying.

[Daniel Broadway]

Helen, could you perhaps post screen shots of your keying with Primatte?

[Ray Van Eng]

Did any bluescreen chroma key shoots with the HD10U or HD1? Anything special to pay attention to in both shooting and editing? Please share your experience here. Thanks!

[Mark Jervis]

I don't have any info yet but I have a day long greenscreen shoot with the hd10 on sunday and will report my findings.

[Ray Van Eng]

Marvelous, Mark! Have a great shoot.

[Mauricio DelaOrta]

I have been doing very simple 'green screen' shootings, and found out that the camera performs nicely if you take standard rules into consideration:

2. Light your bluescreen evenly (no shadows or hotspots)
3. Place your actors with enough space in front of your screen so that light reflecting from it wont cause green spill.
4. Light your actors/set/props accordingly.
5. Use good Chroma key software/hardware

I've been using Vegas 4.0 to add the effect. This software is quite flexible (for its price), and will let you make some adjustments if your bluescreen scene has some lighting errors.

The extra sharpness of the HD1's image made my life easier in post, since had considerably less greenspill than the results I got from a XLS-1 i borrowed before.

Cheers,

Mauricio

[Heath McKnight]

Do a search for Greenscreen HD10; I know someone did it...

heath

[Ray Van Eng]

Thanks for the info, Mauricio. Specifically for Vegas 4.0, I was actually leaning more towards getting the Premier but I have read some not so good comments concerning the Adobe software’s handling of chroma key subjects.

I would imagine all the usual rules apply in lighting the screen, but was a bit surprised to hear you say that the extra sharpness of HDV actually helped the chroma key shots, i.e. less green spillage. Interesting. I am more of a Bluescreen person myself being growing up in a TV station environment.

Would love to read more comments from other people, not just in shooting but also editing too. Thanks in advance.

[David Newman]

Green-screening has a slight advantage of using blue for any sampled chroma video system (DV 4:1:1 and HDV 4:2:0), as the green holds more signal in the luma, resulting in a sharper key.

The issues of chroma-keying will be the same whether you use Sony or Adobe products -- it primarily depends on your setup efforts. However, does have an impact and I know higher-end keyers are available for After Effects and Premiere, so there is a lot of choice.