2013 has been a busy year - and it is almost one year ago to the day since my last post!
I am constantly learning about new production processes as a member of the Virtual Production Committee. Chaired by David Morin and Co-Chaired by John Scheele this group is a joint technology subcommittee of the following organizations :
Here is my report for VPC Meeting no. 8 that was held on October 3rd, 2013 at Warner Bros Studios:
CASE STUDY: The Making of “Gravity”
Chris DeFaria, Executive VP Digital Production and Animation
at WB and our host for the evening, told of how 4 years ago when introduced to Gravity, he suggested to director Alfonso Cuaron a compositing technique developed by Alex Bixnell, VFX Supervisor
on Little
Man, in which they shot the head of the character independently of the body
and comped them together in a low-tech way, but for Gravity only the faces
would be real and the rest of the movie animated.
Alfonso had already created a 7½-minute pitchvis for
Universal with previs artist Vincent Aupetit, formerly of Framestore. The
project was deemed cost-prohibitive by Universal, but this pitchvis and
DeFaria’s confidence in coming up with an affordable solution got the production
green lit at Warner Brothers. DeFaria
credited William Sargent of Framestore for
undertaking the pitch from the beginning and brought Framestore on board to
lead the team(s).
He presented the 16-minute long opening shot of the film
that gave the sense of the movie, and added that the concentric graphic (from 5D- see below) shown by David Morin
during his opening remarks, is very relevant. For Gravity, all phases of production—previs, postvis,
editorial, even script were concurrent, intersecting and informing each other,
unlike any film he had ever worked on.
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| Production Design Mandala |
David next introduced Chris Watts, VFX Supervisor, also
brought on by Chris DeFaria, as a consultant to work with Framestore in exploring
techniques to achieve total realism for the zero gravity shots.
Watts showed short clip from the voluminous NASA footage provided
by WB for reference. He noted several key challenges; one would be to get the
lighting right – there is no atmospheric perspective in outer space. Photographic
tricks such as scale do not work. Another challenge was to figure out a way to
free up the actor from cables and uncomfortable rigging so they could focus on
acting. Actors on cables are very difficult to shoot which would be compounded
by the length of the shots that the director was looking for.
Alfonso initially wanted the capability to re-light and
re-photograph the actors in post, which would require doing 3D performance
capture, so they tested a technique using the Light Stage developed by Paul
Debevec at ICT.
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| ICT Light Stage |
The results were very good, but the shoot was problematic.
They were able to shoot only 5 minutes a day, creating a lot of footage that took
4 hours to download. In addition, Alfonso was not comfortable shooting in a
dome of blinking lights. Alfonso decided he must commit to shooting one angle
and lighting one way, meaning he would need to previs the entire movie.
Watts knew their approach would be to shoot some form of
stationary person with a moving camera, but he was not a fan of motion control,
since it is not an easy process for zero gravity performance. Then Chris DeFaria forwarded him an article in
Wired Magazine about Bot & Dolly
(formerly Autofuss), a San Francisco based company that was repurposing
automotive assembly robots to shoot movies.
Watts contacted Bot & Dolly Creative Director Jeff
Linnell, who sent him a clip of the robots in action proving they had the
technology needed to get the movie made.
He went with Chivo, the DP for Gravity, to San Francisco for a tour and demo.
Watts told how he gave the B&D team a
Maya file of the previs before lunch, and to his surprise, by the time they
came back, found the B&D crew ready to shoot a test.
For the test an actress stood in front of green screen on a
plexi block and shifted in mid-air, grabbing onto invisible weightless objects.
The camera, lights and reflectors, all mounted on robots, moved in sync,
orbiting the actress as she moved and turned.
The objects she was reaching for would be CG and comped later in post,
but she was live-comped on set directly into the previs Maya file. Seeing the live-comp convinced Chivo, Alfonso
and Chris DeFaria that this was the way to go.
Jeff Linnell, Creative Director at B&D spoke next about
the tools they created for Gravity. The B&D team spent a year doing
software development for the motion control rig. Linnell emphasized the
democratization of their system. It was not practical to have proprietary
software that only his team could program. They developed Move software that sits on top of Maya. Anyone who can operate Maya can operate the
robot. Move enables a robot in the
real world to be moved in Maya, and conversely, the robot can be moved in the
real world and that movement recorded back into Maya.
This standardized tool optimized collaboration by allowing the team to operate the robot from their Ipads. Framestore was able to animate all the camerawork for the movie in advance, while the B&D team validated the physics on set. Every shot planned in previs was achieved. The toolset they created allowed flexibility and creative control that would not compromise the demands of the most particular director or cinematographer.
The robot on Gravity was a 6-axis industrial arm capable of lifting
300 lbs. and moving at 4m/s. It was
mounted on a 7th axis track and had a pan-tilt roll head attached to
it (for 10-axises) Additionally, the actors were in a gimble rig that was also
on a pan-tilt roll axis, totaling a 13-axis robot on set. . Precision was paramount. The repeatability is
.05mm in accuracy at full speed. Every shot was a synchronized programing of
movement of actors, camera and lights.
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| LED Light Box with Bot & Dolly Camera Rig |
David then introduced Chris Edwards, CEO of Third Floor Inc.
the company responsible for the entire previs of Gravity. Edwards noted “Gravity
is an auteur film created by a director who envisioned the script in three
weeks by writing it down, and he wanted to complement the story with very
innovative, almost revolutionary camera work.“ Alfonso wanted extremely long
shots that ended up on average 12 minutes long. Most films are over 2000 shots. Gravity was 192
shots total. Within the first 30 minutes of the movie there are only 3 seamless
cuts. And he wanted a high degree of accuracy regarding the geography of the
earth and its orbit.
Edwards showed the original pitchvis (one continuous shot) Alfonso
had created 5 years ago for Universal by Vincent Aupetit, now Previs Supervisor
at Third Floor’s new facility in London.
Third Floor worked another 11 months in collaboration with
Alfonso and Framestore to create the previs Maya files that Chris Watts later
took to Bot & Dolly. Edwards
described how Alfonso developed a close working relationship with each previs
artist, using physical models and lipstick camera to explore shots and encourage
collaboration. These meetings got into so much detail that they were video
recorded as a way to keep everyone involved on track with his vision.
All 192 shots were first conceived in previs as a hand-animated
creative pass to get a clear idea of all the elements in a scene. For many of
the shots they also did a simulated pass in Motion Builder. They took advantage of the Motion Builder’s
physics engine feature and by changing some of code, allowed the animator to
fire the jet packs with an xbox controller and control the tethering.
The Art Department, led by Production Designer Andy
Nicholson, generated 3D set models for use in previs. They worked without direct assistance from NASA, were able to be very
faithful to the research found on the internet. In addition to 3D set designs, concept art, key frames, and 3D set dressing, they provided infinite image and video-based detail early
on that aided the previs, including textures, movement of fabrics, and studies of weightlessness.
Edwards noted the advance in virtual lighting. The previs files
were passed over to Framestore where DP Chivo hand-lit every shot, which drove
the lighting decisions on set. He
acknowledged how Framestore pushed the limits of their resources with great
dedication to make the film possible.
Chris Lawrence, Framestore CG Supervisor on Gravity skyped
in from London. He worked on the project the whole way though to delivery.
Echoing Chris DeFaria and Chris Edwards, Lawrence credited the success of this
production in part to William Sargent’s investment in the project and for
having fostered the creative collaboration between all departments from within
Framestore.
He noted how having the Art Department working in house during
the previs phase afforded them the opportunity to integrate fully designed
assets for a more complete vision very early in the production. And because all departments were digital and
could access data storage at Framestore, the iterative nature of the process
was enhanced.
He mentioned the special effects harness rigs they developed
for Sandra Bullock to aid her performance of weightlessness.
He explained how VFX Supervisor Tim Webber combined 3 shoot
methods: traditional camera and crane with traditional lighting, motion control
camera and LED box, and a motion control wire rig and motion control
camera. These 3 methods were easily
blended together because of the problem solving they did through previs. The
work they did with Chivo to figure out the lighting in previs also paid off in
the end when it came time to reassemble and comp the CG bodies with the real
faces.
Lawrence presented a short video that elaborated on the LightBox
and Tim Webber’s idea of projecting a virtual environment on the LED screens
surrounding the actors. They provided an animated version of the movie as seen
from the actor’s point of view. This visual information was low res, but enough
to give the actors a feeling of where they were in space, helping them to do
their job. At the same time it was a dynamic lighting source that gave subtleties
in color, atmosphere and reflection for every moment of every shot in the LightBox,
making the film feel that much more real.
Q&A
What was the
resolution of the 6 panels in the LightBox?
Each panel was made up of several 5” square tiles @ 64
pixels x 64 pixels
It was low res but a lot of effort went into the of color
calibration of the panels.
Was there any digital
facial performance or digital doubles?
Yes, we worked with a company called Mova that
specializes in capturing facial geometry. We had a rig with genesis cameras to
augment with textures that could be projected onto the geometry.
Can you talk about
safety features of the robots?
We had numerous layers of safety protocols on set that started
in previs.
We ran the robots on the set without a human at variable speed,
and then did the same with a stunt double.
Health and Safety had to sign off on every shot and there was an onset
protocol for that. We also had safety
operators in place, if struck, they could stop the robots immediately.
What was the
hierarchy of the management structure for this film?
It was standard VFX management production structure but
larger.
The Art Dept. was right there with no physical barrier and
that aided the short deadlines.
What was the
translation of Alfonso’s use physical models and lipstick cam to the previs?
It was a visual translation used as reference footage for
the artist. The models were used throughout the whole process and were pretty
battered by the end.
How were you dealing
with scale in space?
Everything was to correct scale, in coherent 3D space. We
tracked the NASA photos and built to them. Chris DeFaria could not distinguish
the CG asset from the original photo reference.
When did you start
working with the Art Department?
It was the around the time that previs got underway till
about 3 months after the shoot. We were able to block out the world early on
with low-res schematics.
As we got a little further along the Art Dept. provided very
accurate models, which Alfonso preferred.
What kinds of motion
capture systems did you use?
Framestore purchased a Vicon stage system specifically for
Gravity.
Motion capture was used to previs some portions of the film.
We also carefully tracked the motion of the helmet with
motion capture camera attached to the lightbox. This was key to matching
subtleties of Sandra’s head to whole body performance later in animation.
Almost all of the animation is hand key-framed because it was difficult to do
motion capture of zero gravity movement.
How long did you
shoot on stage?
The live action shoot was about 3 months.
What was the
resolution of the final render? 2K or 4K?
It was 2K stereo. We invested a lot in rendering. We
converted from Pixar Renderman to Arnold (Framestore’s proprietary engine).
Chivo loved simulated bounce light and we had a lot of heavy models that added
to the render time.
What was the full budget
of the production?
Around 80 million dollars, maybe more with the reshoots.
There were a few moments in the beginning that were needed a year after the
first shoot wrapped.
How did you integrate
editorial into the process?
The Editorial Dept. was also based at Framestore and
integrated very tightly with previs. Editorial for very long shots was
convoluted so it was broken down to story beats instead of shots. Numbering the
actions gave us a way of managing it. The editorial process was very
complicated in both pre and postproduction.
Was there and edit of
previs that really was the movie?
Yes with sound and voiceover. When we got Sandra’s voiceover
the movie became real without a single shot.
How was the 3d Conversion
done?
The 3d conversion of the faces was done from a flat left
eye. Everything else in the frame was rendered in stereo.
How long was Chivo
involved in the previs phase?
Chivo is a key collaborator of Alfonso’s and brought a lot
to the table. He was not there all the time but was at Framestore for about 3
months. He came back during postproduction for some full CG scenes that were
not prelit and gave feedback for that and other stuff we did after the shoot.
How was it to have
the Director and DP with you in house for that long a time?
Did it change the way
you worked with the client?
The client relationship was sometimes a little frustrating,
but overall it was a very positive experience and we were able to do something
we would not have been able to do without that direct collaboration.
How much involvement did Sandra have in previs?
We mostly worked with Alfonso if Sandra had any notes they
came through him.
Was there Sets built
or were they all digital?
Yes the 2 smaller capsules were fully built, and there were a few proxy sets as well.
end of report.
A great in-depth discussion can be found at fxguide http://www.fxguide.com/featured/gravity/
Happy New Year!
JC
Yes the 2 smaller capsules were fully built, and there were a few proxy sets as well.
end of report.
A great in-depth discussion can be found at fxguide http://www.fxguide.com/featured/gravity/
Happy New Year!
JC
