Head-to-toe Greenscreen – to Mylar or not to Mylar?

[khsargenius]

Hi,

I’m a DP shooting a low-budget feature on the RED camera. The whole thing is pretty much on greenscreen and I’m trying to decide how to deal with head-to-toe full-body shots.

Another DP I know recommends laying down shiny/silver Mylar on the floor, so that it will reflect the greenscreen with only minor difference to the rest of the screen. He says that another advantage to this is that you get a natural silhouette where you’d want the shadows of the subjects to go.

However, I’ve heard from some compositors and VFX people that Mylar causes as much head ache as it solves problems.

I shot a trailer for the project in February. We laid down painted canvas on the floor but it was a different colour to the screen (which was spandex), it was difficult to light without affecting the subject / foreground lighting and in the end the compositor ended up doing a lot of roto.

I would like to hear people’s experiences with head-to-toe greenscreen setups, and specifically if you you’ve got any experiences with Mylar…

cheers,

Kim

[tscholton]

Mylar will give you damn near 100% reflections… and then require roto anywhere the contact point is to split out the reflection because chances are you don’t want it 100% and anything else that reflects will be as if it is sitting there. I have done two jobs where I lost the fight against mylar and the roto people spent a lot of extra time on each. I am not a mylar fan.

Jeff

[Marvin Butler]

Hi Kim,
I recently came off something that was mostly greenscreen, we had to shoot them head to toe and composite them into an alpine snow enviroment. I asked that art department bring fake snow for their feet…basically what I am saying is in a lot of cases it depends on what you plan on doing with your footage. however… I still had to do a lot of roto in the end because our snow on set clipped too hot, so my CG snow did not match.

in the end I wish that I had just kept them on the green floor. I would say find a studio with a painted floor. When you can, get your FG to be practical. But these days people are more ambitious with shooting greenscreen (ie. 100% digital sets)

Colin Nicholas Riley
VFX supervisor
Epica International

[Max Glick]

Jeff,

Thanks for your response. Just to clarify – when you say 100% reflections, do you mean all the surroundings, including unwanted set, riggin etc, or do you mean 100% reflection of the foreground element that you’re trying to key out?

–
Kim Sargenius
cinematographer

[Max Glick]

Colin,

Yep, certainly ambitious here! 🙂 Damn near 100% digital sets, shooting on the very, very cheap apart from using the RED camera.

I’ve been told that there most of the time we will have some sort of set on the ground so this problem hopefully won’t be popping up too often.

I’m confident lighting the screen itself to the required level and uniformity, we did a test in February and it worked out well, but I’m worried about the floor. The lighting will be pretty toppy and I think it’ll cast all sorts of shadows on a green floor…

Perhaps time for another test methinks…

Thanks for your replies guys!

–
Kim Sargenius
cinematographer

[tscholton]

@khsargenius 26020 wrote:

Jeff,
Thanks for your response. Just to clarify – when you say 100% reflections, do you mean all the surroundings, including unwanted set, riggin etc, or do you mean 100% reflection of the foreground element that you’re trying to key out?
–
Kim Sargenius
cinematographer

I mean that anything that is reflected in the mylar will be solid. For example if you have a person standing on it there would be a straight down reflection of that person that would key almost as well as the person. My point was that there are very few instances where you want the reflection at that level so you now have to roto to separate the two.

Jeff

[Max Glick]

@neonmarg 26022 wrote:

My point was that there are very few instances where you want the reflection at that level so you now have to roto to separate the two.

Thanks for that clarification Jeff. I’m not a compositor myself – I’m trying to wrap my head around what could be a sticky situation for the ones that will eventually have to do the compositing.

So, in your experience, what is the best way of dealing with head-to-toe shots?

–
Kim Sargenius
cinematographer

[Anonymous]

Hi,
I have been filming and editing some green screen setups with a Sony EX1.
There were two screens, one against the wall and one on the floor.
I found it near impossible to light the floor and the talent without casting multiple shadows.

In the end I had to rotoscope from the knees down and key frame for any movement.

Trying different keyers for the different sections produced almost good enough results, but not as good as the rotoscope. I had hoped that the shadows could have been used as effect in the final composite, but that was not to be – it was also not very controllable.

I am setting up again for some green screen shooting in the near future and would love to hear what solution you go for and if Mylar can be used effectively.

Phill
MacBook Pro 2.5GHz 4 GB Ram, FCS 2, Shake 4.1, Photoshop CS2
http://synapticLight.wordpress.com

[Kjell]

Mylar (or more properly mirror-plex) is only useful for when you really want *reflections* for your comp (ie. standing on a tile floor, on ice, etc)

shadows can be extracted from keying or they can be added in later, depending on what your lighting setup is like. these days the default lighting setup for greenscreen seems to be a buncha spacelights up above for the base and adding floor/back units for shaping on your subject. result? crazy multiple shadows with one or two dominant ones. a good comp/key artist can usually minimize the lighter shadows cast from the multiple spacelights and keep at least some of the shadow from the keylight. (sometimes with spacelights i will black off the very bottom of the unit to prevent directional shadows being cast from this…the net result is less light overall but generally a more diffuse and even illumination of the cyc.

hope this helps

k

[Max Glick]

Kevin,

That makes sense – try and minimise multiple shadows as much as possible. This being a microbudget production there is howver limits to what I can pull of lighting wise – bunch of space light is unfortunately out of reach. I can go with two 12×12 silks for overall ambience, which I was thinking more as a frontal fill but I might have to think of ways of rigging them over head… Food for thought.

cheers,

Kim

–
Kim Sargenius
cinematographer

[Max Glick]

@SynapticLight 26110 wrote:

I am setting up again for some green screen shooting in the near future and would love to hear what solution you go for and if Mylar can be used effectively.

Mate – it would seem that the solution is there is no solution! Only a choice of lesser evils – are you better suited to deal with roto (knees-down or reflections) or multiple shadows. I think I’ll stick to the camera! 😮

Kim

–
Kim Sargenius
cinematographer

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