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Methodology
A pilot study was made in order for the authors to get a more correct view of the professional work and if the described problem really was a problem. The pre study was carried out through interviewing a couple of compositors. These interviews consisted of questions sent out by e-mail to compositors who had graduated from the same education as one of the authors. The answers were sent back via e-mail some weeks later. Their answers made it possible for the authors to describe a well-founded problem, purpose and research questions, and also to have a good foundation for further investigations.
Methods used to find and articulate the tacit knowledge of compositors and lighting electricians were case studies including interviews and observation. The interviews were also made in order to reach understanding of which factors that affect the photorealistic impression of filmed Chroma key material. To find out to what extent these factors can be altered in the compositing process, compositors were also interviewed, while showing examples. In order to reach understanding of how the photorealistic impression can be enabled and facilitated in the film studio, compositors were interviewed and a case study was made including observations of how the lighting was set for a studio filming with Chroma key background. In addition, an interview was done with the VFX supervisor working on that project. Further methods used to test the knowledge found related to this question, were production and evaluation of video clips.
The choice of interviewees was made through contact with several compositing companies and personal contacts of one of the authors. The ones chosen were those showing interest and having time to spare for interviews.
The choice of case study was made through inquiring different production companies of Chroma key projects within an estimated time frame and it depended on if they had time to take us on for interviews and observations of a Chroma key studio recording and postproduction.
Interviews
Interview with compositor at Filmgate, Gothenburg March 2, 2012
The first person interviewed in person was a compositor who had been studying in the same class as one of the authors. He had answered questions in the pre-study phase via e- mail and agreed to meet for an additional interview at his workplace. At the company, he gave a tour of the premises and introduced his colleagues before starting to answer any of the prepared questions. The interview was held sitting down in front of his work computer in a room where other compositors kept on working at their own stations at the same time. When asked for an example relevant for the questions asked, he showed a short clip on his screen. While he answered the questions, the authors took notes and recorded the sound with a smart phone application.
Interview with compositor at FIDO, Stockholm March 23, 2012
This time the manager of the company chose one compositor he saw fit for the interview due to his previous experience as VFX supervisor in Chroma key studios. During the interview he sat at his workstation in a room together with three other compositors working at their own workstations. He started to introduce himself by showing what he currently was working on and then he continued by answering our questions, which he allowed to be recorded with a smart phone. When asked for relevant examples he was hesitant whether he had any but another compositor in the room overheard the questions and gave an example, and told what difficulty there had been and how he had solved it.
Case study – ADAY commercial March 24, 2012
The venue, in which the Chroma key studio was set up, is situated in the suburbs of Stockholm in an industrial area. The studio is provided with a high ceiling permanent rig, which is appropriate for attaching the temporary rig. There is also an adjacent recreational room, kitchen and canteen.
During the day of the rigging, the director, producer, photographer, two stage decorators and two electricians were present. The producer presented the electricians to the authors and said that those were the people to talk to. While the authors presented themselves, the electricians were about to finish their meals and start working again.
The photographer came into the studio and all the others gathered in a cluster. They talked about the lighting, among other things. For the first time the photographer showed the background plates to the electricians, followed by an explanation of what he wished for in relation to the lighting.
The authors observed while the electricians were rigging the lights. Since they were both running around working, it was rare to find opportunities to ask them questions. In spite of that, a few questions were asked and answered in between workloads. However, they were hesitant at answering and sometimes they answered with a question or answered by explaining something non-relevant to the question.
March 25, 2012
The following day was the day of filming, and the rigging work continued for the electricians. The authors observed and found moments to ask a few questions to the electricians.
The VFX supervisor from Chimney Pot arrived to the studio as agreed with the production leader. He put up his laptop to be able to test the keying of the material. Next to him there was an editor sitting at his workstation and was prepared for his work as well.
The VFX supervisor was asked for a brief interview, which was carried out sitting by a table in a corner of the canteen. Furthermore, one of the authors sat behind him, to observe procedures, throughout the rest of the day.
He was also contacted through e -mail some days afterwards to give information on when the material was going to be processed. He was solicited again via e-mail a week later for further information on how the compositing process had gone.
Production of video clips
Further investigation was made to test the knowledge found related to studio lighting. Sample video clips were produced for the authors’ evaluation of whether inappropriate lighting could be processed in the compositing phase to render a photorealistic result. The sample video clips were recorded in a temporary set up Chroma key studio and then processed in the software Nuke, by the author who is also a compositor. The investigation was limited to two background plates with 14 foreground plates each with different lighting conditions.
Studio recording at the University of Jonkoping March 29, 2012
As previously recommended by professionals in the theoretical background, the background plates were shot first. These included one soft light background with light, which casts very few shadows (see figure 5), and one hard light background with sunlight from one angle casting distinct shadows (see figure 6). According to these backgrounds the studio lighting was planned. What was found relevant to experiment with were the values related to lighting, which were mentioned as factors that affect the photorealism. These were intensity of light, direction of light and colour temperature. Filming the foreground plates for these backgrounds, the three factors were altered in two levels, one subtle and one strong. This meaning that the light in the studio was set with a subtle and strongly altered lighting in respect to the factors intensity, direction and colour temperature, one at a time.
The Chroma key studio was set up in the lighting laboratory room at the University of Jonkoping. The lights and other equipment came from the storage of the lighting department of the University and the blue cloth backdrop came from the TV-studio at the same University. The setting up of equipment was done the day before the recording. The camera used for recording all material was a Canon XHA1s, HDV 1080i, and it was set on SD 16:9 and 25F.
The lighting of the set was done systematically, starting off by lighting the stretched blue screen evenly and blue enough for the camera to interpret it as blue. The blue screen was lit with a Selecon Acclaim Axial 600W and two Luci Dela Ribalta 1000W, all with added blue coloured gels and dimmed to 40%, (figure 7). The placement, direction, intensity and colour were decided after several attempts using the camera as a measuring instrument. The blue gels were added for the blue colour of the fabric to come forth and not be washed out. To make sure the light was even on the blue screen the zebra function of the camera was used, set to 70. The height of the camera and the focal length were adjusted to match the background plate. For all the shots taken the distance between the actor and the blue screen was 1,8 meters and the distance between the actor and the camera was 2 meters.
Lighting for video clip A – soft background & soft foreground
To continue, the lighting was set for the first scene representing an appropriately lit foreground plate for the soft light background, which is seen in figure 8:A. The key light was set from the left (always referring to the perspective of the camera angle), and the fill light from the right, as seen on figure 7:A. The key light was angled in 45 degrees from the actor’s point of view. This light came from a Fresnel light called Arri300 with a full CTB and a full diffusion gel attached. The fill light constituted of two Arri 650 lights with a half CTB, both directed onto the white wall on either the left or the right side of the room. The intensities and the direction were set to match the background plate with even lighting and soft shadows. This was the lighting in which the white balance was set, to serve as a reference for the other inappropriate lighting sets.
Continuing with the inappropriate light sets for the same background, one of the factors intensity, direction and colour temperature was altered one at a time. The specifics of the alterations was controlled and written down on paper.
Lighting for video clip B & C – soft background & hard foreground
For the soft light image with an inappropriate intensity of light, the subtle alteration (seen in figure 8:B) was made with a brighter and less diffuse key light by changing the full diffusion gel to a half. The stronger change came through removing the half diffusion gel, making the light even more intensified.
Lighting for video clip D & E – soft background & warm foreground
For the soft light image with an inappropriate colour temperature, the subtle alteration came when the CTB gels were removed and the stronger alteration when a full CTO gel was added to all of the lights.
Lighting for video clip F & G – soft background & light from different directions
For the same image with an inappropriate direction of light, the subtle change was from moving the key light to come from a higher upward angle, roughly 25 degrees, and closer to the camera angle, as seen in figure 7:F. The stronger change in direction came from moving the key light to the other side of the camera angle, the right side. The fill light remained constant.
1 Introduction
1.1 BACKGROUND .
1.2 PURPOSE AND RESEARCH QUESTIONS
1.3 DELIMITATIONS
1.4 OUTLINE
1.5 GLOSSARY
2 Theoretical background
2.1 DIGITAL COMPOSITING
2.2 PHOTOREALISM
2.3 CAMERA MOVEMENT
2.4 LIGHTING FOR CHROMA KEY
2.5 LIGHTING INVERSE SQUARE LAW
2.6 LIGHTING CONTROLS .
3 Methodology
3.1 INTERVIEWS
3.2 CASE STUDY – ADAY COMMERCIAL
3.3 PRODUCTION OF VIDEO CLIPS
4 Findings and analysis .
4.1 FACTORS AFFECTING THE PHOTOREALISTIC IMPRESSION
4.2 WAYS TO COMPOSITE FOR A PHOTOREALISTIC RESULT
4.3 WAYS TO FACILITATE AND ENABLE COMPOSITING
5 Discussion and conclusions
5.1 DISCUSSION OF FINDINGS
5.2 DISCUSSION OF METHOD
5.3 CONCLUSIONS
6 References
7 Search terms
8 Appendices
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Digital Compositing for Photorealism and Lighting in Chroma key film studio
