Main Media Filmmaking
Certificate in Collaborative Filmmaking at Maine Media College

On Set Effects Supervision: A Case Study: Working with Greenscreen by Mark Sawicki

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Reference: StudentFilmmakers Magazine, January 2015. On Set Effects Supervision: A Case Study: Working with Greenscreen by Mark Sawicki. Pages 38, 40 & 41.

Many of my students like to hear the war stories of actual productions from real effects supervisors. A frank discussion of the actual work experience can vary dramatically from the sanitized DVD bonus features we all see accompanying the movies these days. I would like to relate a good example of how an effects supervisor integrates in a very positive and productive way into a moderately budgeted film. I will leave out the name of the film and players aside from myself to avoid the issue of permissions. The film I most recently supervised involved a shot where the two main actors performed in a real office located on the outskirts of Los Angeles. The challenge was to put Century City as a background outside of the windows. This seems simple and straightforward, but even with a simple shot such as this, there are quite a number of issues that come up.

Happily, the first thing that happened was that the veteran cinematographer visited our shop to let us know what type of shot he was planning and what we needed. This was a rare opportunity. To prepare for the meeting I looked the DP up on to see the background of the cameraman. The first thing I said when I met the man was how impressed I was that he had shot over 40 features and took the time out of his busy schedule to consult with us. As a supervisor, you must get the point across that you understand that this is the client’s movie, and you are there to help and learn from them.

We chatted about the shot and the director of photography wanted to know what material we preferred for green backing. I mentioned that the digital green fabric manufactured by was the best in my experience. I also made sure to mention the obvious question that often gets overlooked which is what color are the costumes of the performers? If someone is wearing a bright green sweater in front of a green screen, the performer’s sweater would disappear. If the green sweater couldn’t be swapped then digital blue would be the proper choice for the composite.

The other desire of the cinematographer was to use as much natural light coming through the window to light the room as possible. I said that as long as the green screen covers the actors’ movements, the other mattes could be drawn around the other windows precluding the need for other green screens. We left the DP saying he would check on the costuming and invited me to the set for a scout at the location the day before we shot.

Here we get into the reality of travel in Los Angeles. The set was located 37 miles from where I live. My call time was 9:00am, but the crew call was 6:00am. I am a firm believer in the old adage that it is better to be an hour early than a minute late.

I left my home at 6:30am to arrive at 8:30am. Yes, that 37 miles became 2 hours of travel because I didn’t time the rush hour properly. I did make it on time, but as it often happens, I waited till 10:30am before the principals had a break from filming so that they could speak with me.

When you are blessed with some time before a meeting the last thing you should be doing is eating all the goodies at craft service and trying to pick up the attractive extra that happened to wink at you. I used this time to observe silently and out of the way how the show was working. How was the DP lighting? How was he interacting with the director? How did the director work? Did they do a lot of takes? Did they stick to a plan? Etc.

The next valuable thing I did was find the room that the green screen would be shot in. Having located the room I was able to ponder all the possible issues that could come up long before I had to meet with the DP and director to give my two cents. You definitely don’t want to appear like you’re making stuff up at the last minute. When I saw the room, the first thing I noticed was that the ambient southern light that the DP envisioned was actually harsh directional sunlight through the windows that created many reflections on the glass. The plan we discussed was to place flat plywood panels covered with green fabric directly over the windows for the green screen. Because they were fabric, this green surface would not be able to capture reflections. The other thing I noticed was that the set included many chrome plated lamp fixtures that were directly in front of the window. Needless to say, chrome in front of green will reflect the green light and become completely invisible in the final composite.

As you can see, the way I work is to look for issues, and then, decide if they can be handled in the compositing end or it absolutely must be addressed on the set. If at all possible you want to reduce any undue work or pressure on your filmmakers. They are making a movie after all and not the greatest green screen shot ever done.

Before I knew it, several producers, the director, and DP burst into the room to have a meeting. It is the first day of the shoot, and everyone is getting used to each other. Hierarchies are being established, and you want to come off as the person who saves them all time and money. You are not there to pontificate and show everyone how much you know. The conversation basically went like this:

The DP says, “Here is the room, and while I’d like to have a static shot, we may have to bring her in with a dolly or a pan. You have any thoughts Mark?”

My reply was as succinct as possible: “Well, a lot depends on when you want to shoot this. I notice that there is quite a lot of bright sunlight streaming into the room right now that casts many reflections on the glass. Now, of course, it’s impossible to put a green screen out behind the windows when we’re 10 stories up, so if you would like to keep those reflections, we could put them in afterwards which will let you use the fabric screens you’ve all ready prepared. Other than that, I just have some production design considerations regarding those chrome lamps which will disappear. It would be better if we could use those dark fabric lamps in the other room.”

The prop man says: “Those lamps over there?”

I reply: “Those would be great.” (I let them make the choices whenever possible)

The DP wraps it all up by turning to the director: “Okay, fine, this will work nicely. I know exactly what he’s saying”. The DP then leads the director out of the room and turns to me with a decided “Thank you”.

Now, that “thank you” was very clean and concise. I noticed as I was mentioning the fact that we couldn’t put green screens outside the window, a strange confused expression fell across the director’s face. She was completely absorbed in the comedy and performers and was becoming thrown by this sudden input of technical jargon. My quick segue towards “put those lamps in there, and it will be fine” made everything simple again. The DP and his “thank you” let me know that I need say no more. Everyone is new, it is the first day, time is a wasting, and they want the energy to continue. The only reason an effects supervisor is allowed to join their party is that they have the presence of mind to obtain insurance that what they do will go well. What they don’t want is someone to say “no”.

So the next day, I leave my home at 5:00am and arrive at 6:00am (no rush hour). I meet and greet the key grip and have breakfast with him. The key grip is a very important person to befriend. A grip can save your day or make it miserable. Depending on the personality of the grip, I find I may have to modify my interaction a bit. In this case, I switched from the champaign conversation one has with the creative crowd to havin’ a beer with the boys. This does not mean to convey in any way that grips are not creative. In fact, they are one of the most creative people on the set because they help the DP modify and adjust the illusive and ever-changing dynamic called light. Unfortunately, the pecking order in the business oftentimes overlooks their substantial contribution. If some grips are gruff, it is because they are truly the unsung heroes of filmmaking. They deal with all the grief and get little glory. If you want to know the true lay of the land on a set, just ask a grip. They don’t pull punches. We became acquainted and swapped movie war stories and got along very well.

By the time the actual shoot came around, things were moving very fast. The DP had time to think about my comments and acted upon them to alleviate the problems. He decided to cover all the windows with green and completely block out the natural light. In this way, we could make the outdoor light anything we wanted. Since we covered all the windows, he had the liberty to move the camera and made it easier on me by executing the move using a simple pan and tilt as opposed to a more complicated boom, dolly, or track. Simple pan and tilts are much easier to “track” or move added elements such as the Century City background into a shot during compositing.

The key grip went out of his way to make sure the green panels lay perfectly flat against the window so that the mullions were revealed accurately. The camera crew was very helpful by supplying me with lens information, F stop, camera height and angle. Normally, I would have been a silent over the shoulder observer to obtain this information.
Just before we shot, the director had a bit of inspiration and decided to place a cute figurine on the desk between her performers. The figurine was of a little hula dancer standing on a green base with a green skirt. At this point, I made the wise decision to bite my lip and let it go. The figurine was a minor part of the shot for me to fix but was a brilliant bit of inspiration for the director. If I put my foot down and said she could not use that figurine, I would be the killjoy who was spoiling the party.

When the shots were done, the DP also took the time to do me the favor of shooting a reference plate without the actors. We removed all the green screens and shot the same move without the actor so that we had a record of what the actual background did as far as movement and focus. This clean plate is also extremely useful for the process of “patching” which is covering up unwanted elements of a shot with elements pulled from a clean plate. In this case, the DP had to put up a key light at the last minute that was in the shot during a tilt up. There was not any way to hide the lamp so he asked at the last minute if I could get rid of it. I had a second to look at the lamp taped to the wall and deduced that I could pull the image information from the bottom of the wall and “patch it” over the lamp with a picture element of the wall. I was able to quickly say, “No problem.”

In no time at all, the shot was done, and I was asked to hang out in case they had the call for another green screen. During this downtime while the crew had left the set, I took my still camera and took stills of the back side of all the lamps and artwork that were in front of the window. These stills can be used later as reflection elements for the glass to add a touch of realism.

I had a nice lunch, and afterwards, the DP made the clever cost saving decision to simply lower the blinds to cover the windows for the next scene. I was excused with good feelings all around. This is a classic example of how the creative, technical and political dynamics work on a film set. As an effects supervisor, my job is to create a flawless effect in as transparent a manner as possible for the creatives on the set. Be humble, be helpful, and respect everyone from the lowly PA to the director and producer. On a well-run set, everyone works as a team and overblown egos have no place.

Mark Sawicki is the visual effects supervisor for Custom Film Effects. He has authored the book, “Filming the Fantastic,” published by Focal Press ( Mark is also a SAG actor. His most recent appearance is as the villain in the sci-fi comedy “Rescue Rocket X5.”

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