Z1 and Greenscreen
Posted 10 June 2005 - 09:27 AM
Shooting a series of commercial on 16mm but using HVR-Z1 with digi-green for the advertiser's pieces to camera. We're scared of film with her as she needs an autocue and a bottle of wine for 7 second grabs. Bound to roll of a good hour of tape. Has anyone noticed problems or issues with greenscreen? Any infometion would be great as I'm not sure if I'm gonna be able to test thoroughly.
Posted 06 July 2005 - 11:23 PM
Posted 07 July 2005 - 01:46 AM
Posted 07 July 2005 - 03:40 AM
The HDV spec sheets claim that is a 4:2:0 colour system (although I reckon this should be 3:2:0 cos it only records a width of 1440 not 1920 pixels for its 1080i setting). So this means that the colour part of the signal is actually a quarter (or a third) the resolution of the black-and-white signal. So this is why you're chromakey would suffer aliasing and lack of detail if viewed at HD. However, if you use a software downconverter that cleverly converts your YUV HDV to RGB SD, you could theoretically end up with an RGB SD signal full ish resolution for all components (because there are 720 colour samples per line, and every other line contains each colour component so 520 lines in all).
That only works for SD though and is a trick we developed to shoot HD-CAM green screens for standard definition masters.
It all goes wrong if you select the 720p setting, as opposed to the 1080i setting though because the resolutions go down. It also depends on your software doing a clever down convert.
Posted 09 July 2005 - 12:32 AM
Posted 09 July 2005 - 12:47 AM
Posted 11 July 2005 - 02:59 PM
Looks great. Far better than any DV keying I've done, and down rezzing to DV, it still looks great. All I did was a single click in each of the clips to select the backing color, no tweaking at all. I bet if I spent more than ten seconds setting it up, it would look awesome.
I don't own the Z1 yet, but this little tidbit just sold me on it, even though all of my work is currently SD out, this will save alot of time during compositing (which I do quite a bit).
I'm surprised I didn't see more aliasing. everyone I've talked to cries about this, and I just don't see that much.
Edited by r_j_rock, 11 July 2005 - 03:06 PM.
Posted 11 July 2005 - 03:42 PM
Another question on your green screen. I noticed there was quite a lot of green bouncing off the shiny chair which I?m sure will be a pain in the ass later. What is the solution to dealing with these reflections.
Posted 11 July 2005 - 05:51 PM
Posted 11 July 2005 - 06:49 PM
I did a bad light set up on my test just to see if the HD was easier to key. We do key DV but it is really hard to get a good key. I have a DV green key plug in (DV Garage) I think that is what it is called. It helps the key but always looks fuzzy on DV. The HD sample keyed razor sharp. I usually would do a garbage matte to key out the bad areas but this example was just a test. I had the camera on demo and did not have time to try setting up a good key. But I can tell from my test the HD will key great