TUTORIALS | VFX supervision tips
● The key role of the
on-set VFX Supervisor
is to gather all the data
needed to complete the
job. This month, four
supervisors share their
hard-earned expertise to
provide a full checklist
TIPS & TRICKS
Our experts
this issue…
NICOLAS AITHADI
Nicolas is a VFX
Supervisor at the
Moving Picture
Company, currently supervising
X-Men: The Last Stand.
www.moving-picture.com
OYSTEIN LARSEN
Oystein is VFX
Supervisor at Toxic in
Norway. Former credits
include the Matrix sequels,
Catwoman and The Ladykillers.
www.toxic.no/toxic.html
CRISTIN PESCOSOLIDO
Cristin joined Meteor
Studios as a VFX
Supervisor in 2004,
where she’s supervised
Catwoman and Elektra.
www.meteorstudios.com
FRANK WEGERHOFF
Frank is an independent
VFX Supervisor, with
credits including Das
Wunder von Bern. He’s working
on Blood and Chocolate.
[email protected]
Supervising a VFX shoot
On-set reference material is the key to realistic visual effects. Discover what
data to record – and how to record it – with this complete set of expert tips
W
hether working on a major feature, where
Preparation for a VFX shoot starts in early preproduction,
camera data is collected by on-set wranglers,
before you’re anywhere near the set. You will already have
or on a smaller production, where you alone
gone through the storyboards with the director, rendered
will collect all the data you’ll need, knowing
up previsualisations, and planned which elements to shoot
what to record on set is essential to the role of the Visual
separately. You’ll have a good idea of each camera and lighting
Effects Supervisor. Without the right information, you’ll
set-up and, on a professional shoot, may have arranged for a
waste days in the studio later trying to track shots, match
motion control rig to capture multiple elements. You’ll also know
on-set lighting, or replicate textures.
which shots need to be tracked, in 2D or in 3D. Miniature shoots
All too often, something unexpected happens
mid-shot, and it’s at just those times that the VFX team are
called in to rectify the problem. If you’ve documented what
come with their own challenges, but without the actors on set,
there’s more opportunity to get involved in supervisory work.
In this article, we set out 15 essential tips on how to record
went wrong, you’ll understand what it is that you need to
all the necessary data, as provided by our international team
fix, and how you can do so. And this is just the beginning.
of experts. We will conclude with a checklist of everything
How many times has a ‘simple 2D comp’ escalated into full-on
you need to bring along to the shoot, while further reference
3D in post, when the director decides that the shot is “missing
material, including examples of lens grids and camera report
a little something?”
sheets you can copy for yourself, can be found on the CD.
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VFX supervision tips | TUTORIALS
IN FOCUS | The camera report sheet
The camera report sheet is the first place
you’ll go when looking for information about
a shot. Always record all of the information
from the slate, as it will be removed in the
rough cut. In the sheet shown on the right
(a full-size version can be found on the CD
for you to adapt to your own projects), 28 is
● Lens distortion grids can be made by mounting a printed A3 grid on
polyboard. The cross is lined up with the crosshairs in the viewfinder
the scene number (from the shooting script);
001 refers to the first FX sequence; and 005
means this is the fifth shot in that sequence.
The sheet should also contain the following
BE PREPARED
information about the set up of the shot:
Before you even reach the set, know your shots inside out, including
know which elements you’ll need to shoot and how they’ll be
photographed. You’ll need to have every unit of photography
covered, and depending on the complexity of the shoot, you may
need assistants for each unit. While one is taking notes, another
could be setting up tracking markers, and a third helping queue
camera moves on the motion control rig. Make sure each assistant
has access to all the equipment they’ll need.
• Shot description: a brief aide memoire
when reviewing your notes in the office
• Lens information: particularly for zoom
lenses. Include any serial numbers
• Frames per second: was the shot normal,
high speed or slow motion?
• Camera roll number: found on the mag
• Any filters placed on the camera lens
OBSERVE ON-SET ETIQUETTE
Be friendly, know who’s who, and don’t pester the wrong people
for information they don’t have. Your allies will be the Camera
Assistant, who will provide you with much of the camera information
• Height and focus distance of the camera:
measured from the film-back
• Tilt of the camera: measured with an
inclinometer placed on the base plate of
the camera. Some camera heads have a
scale to show this, but it’s rarely accurate
• Shoot dates: on longer shoots, filing
reports by date, unit and location is vital
you’ll require, and the Script Continuity Supervisor, who will also be
recording camera data. Remember, there’s no reason why the crew
should understand visual effects jargon, so talk in a language they
understand. Explaining what you’re doing, and why you’re doing it,
is a good way to build productive relationships.
Camera Assistant for their camera reports. If they miss vital lens
BE FAST, AND BE INVISIBLE
information on a take, you’ll be the one struggling in postproduction.
Film shoots are extremely expensive and, unfortunately, the VFX
Any data you capture will be used in a variety of situations, from
crew (however unfairly) have the reputation of being the ones to
reconstructing precise models of the set in 3D, to matching on-set
hold up the shoot. Since time is money, work as fast as you can. Let
lighting or camera positions, or tracking live-action footage.
the shoot run smoothly as you gather data from behind the scenes.
While tape measures are fine for miniature shoots, it’s worth
investing in the more expensive laser range-finder for live-action
ASSIST THE DIRECTOR
shoots. Also carried by the Camera Assistant, these are good for
Do whatever you can to help the Director get the images he needs.
measuring distance up to about 150m, and are accurate to 1cm
You’ll need to help in creative decision making, as well as ensure
or less. When you next need to measure the height of a cathedral
you’ve got the visual effects shots covered technically. Set-ups
ceiling with a tape measure, you’ll wonder why you never made the
you’ve proposed in preproduction may not work out as planned,
investment earlier. (You can buy laser measuring devices from
so you’ll need to think on your feet. A background in photography
www.microglobe.co.uk.)
helps, as does a good eye for composition. If your knowledge of
cinematography is sketchy, now’s the time to do some homework.
SHOOT LENS GRIDS
Start by purchasing the American Cinematographer Manual edited
Unless you’re trusted by the Director of Photography, and
by Rod Ryan (1993, ASC Holding Corporation, ISBN 0935578110).
experienced enough to operate the film camera yourself, ask the
Camera Assistant to shoot a lens grid, full frame, for each lens. (An
example can be seen at the top of this page, and is also included on
You can never collect too much data. Not only will you need to know
the CD.) Lens grids are a way of measuring the barrelling distortion
everything about the camera settings, you’ll also need to know
of any particular lens, and are used back in the visual effects office
the camera’s relationship to the set, positions of the primary lights,
to ‘undistort’ the scans when compositing. Shooting a lens grid is
the set’s layout and the positions of the actors. Don’t rely on the
particularly important for wide-angle lenses with greater distortion.
● Shoot a visual effects slate
before HDR or photogrammetry
stills. It can be as simple as
handwritten notes on paper
▲
MEASURE EVERYTHING
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TUTORIALS | VFX supervision tips
Slate the lens grid with a note of its make, model and focal length.
There should be a ‘grid warping’ tool in your compositing software
that enables you to ‘undistort’ the plate using the distortion you’ve
captured in the lens grid. All you have to do is create the same
number of lines as your lens grid and pin its points to match, before
finally applying the warp effect.
TAKE REFERENCE PHOTOGRAPHS
Shoot everything you can with a good quality digital stills camera
– something capable of taking shots in excess of 4MP, and that
can shoot in RAW format (we recommend digital SLRs that offer
exposure bracketing and interchangeable lenses). You’ll need
general reference stills showing each lighting and camera set-up,
as well as the layout of the set. If there’s any possibility you’ll need
to reconstruct elements of the set in 3D, shoot as many texture
references as you can. However great the temptation is to fire
● 8cm diameter Christmas tree baubles
make excellent light probes on a miniature
shoot. To create the grey ball, spray
the bauble with an 18 per cent grey
automotive primer
off the camera flash in low-light conditions, don’t use one on set
real-world reference (for more details, see the tutorial on page 58).
without warning everyone first. And, as obvious as it may sound,
Set up your digital camera on a panorama head and take a series of
never fire a flash while filming! (This has reportedly been done.)
stills by rotating the camera around its optical centre. Bracket each
exposure five to seven times, either manually by incrementally
SHOOT HDR PANORAMAS
varying the aperture one stop from the previous image, or by using
High Dynamic Range (HDR) images, created from multiple exposures
your camera’s auto exposure bracketing function. Overlap the sets
of the same shot, provide a means to light a 3D scene to match a
of images to create a 360-degree panorama. The rotation between
overlapping tiles will depend on the lens and resolution. When the
bracketed images are combined using a tool such as HDR Shop, the
HDR log image has a greater dynamic range than the individual
exposures, affording more definition to rendered highlights.
IN FOCUS | Drawing up a plan
ALLOW FOR SET RECONSTRUCTION
HDR images are used in 2.5D reconstructions, or photogrammetry,
where photographs of the set are re-projected back onto 3D
geometry, then rendered with a virtual camera. Shoot the set from
a similar angle to your 3D virtual camera, matching the lens. You’ll
need to photograph at least six or seven images, which should have
overlapping features visible in at least a few of the images. If you
don’t have the time to work with HDR images, single exposures will
do. If your virtual camera moves significantly through the scene, you
may need to shoot image tiles from key points along its move.
MAKE USE OF LIGHT PROBES
Grey, chrome and white lighting reference balls are used to set up
3D global illumination in the VFX studio. They’re mostly used
mounted on sticks to avoid unnecessary issues with fingerprints,
● It pays dividends to
have a notebook handy
for all manner of data
collection – in this instance,
for noting on-set camera
and light positions
and should be photographed for each lighting and camera set-up.
Leave the film camera in its set-up for the shot; have the Camera
Assistant shoot a VFX slate marked up with the shot number, lens
and focal length; place the lighting reference ball where the main
action occurs, then run a few frames of film. If the action moves
across a large area, shoot the reference balls in positions that span
If you’re shooting on a stage, ask the art department for a copy of its floor plan. Out on location,
survey the site as accurately as possible, and sketch out both plans and elevations. You’ll need
detailed measurements of anything you may need to reconstruct in 3D. Additionally, for each
lighting set-up, mark the locations of the primary lights on the plan. It’s always helpful when you’re
back in the office, matching the scene in 3D, and trying to determine where exactly to put the
keylight. Sketches are also vital in describing camera tracks or dollies on the camera report.
its breadth. If the camera set-up is far from the action, and the
reference balls are small, you can request a 4K version of the scan.
If you’re striving for perfection, take care when using balls that
aren’t optically perfect. Secondary reflections caused by ripples on
the surface are quite difficult to fix.
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VFX supervision tips | TUTORIALS
● Reference photos are vital.
Here, they show the layout of
the miniature set for the
subway crash sequence on
Final Destination 3
THE GREY BALL
Images of the grey ball are used to figure out the direction of the
keylight when setting up a 3D scene for global illumination. The
18 per cent grey tone appears neutral to the human eye, and is
equivalent to the average Caucasian skin tone. There’s no need to
buy a special-purpose visual effects grey ball – any medium-size
spherical, wooden or Styrofoam ball, available from a crafts shop,
will serve the purpose. First, coat the ball with a white base-paint,
then paint with an 18 per cent grey, matching the swatch to a grey
reference card (this can be purchased from www.amazon.com).
THE CHROME BALL
● Oystein Larsen makes the final
checks to one of the cameras in the
UCAP rig, capturing Halle Berry’s
facial performance for Catwoman.
A good example of the complexity
of a professional VFX shoot
As an alternative to shooting a HDR panorama of the set, the
chrome ball (or ‘mirror ball’), provides the necessary data needed
for setting up 3D reflection environments. To get full, complete
coverage of the set, you’ll need to shoot the ball twice, from
opposite sides, so that each hemisphere is represented. Specialpurpose chrome balls come in a range of sizes, so choose the sizes
IN FOCUS | The supervisor’s survival kit
you’ll need according to your camera set-ups and location. If there’s
only time to shoot one angle, photograph it matching the film
camera’s aperture for equal depth of field, and from as far away as
possible with a fairly small ball (6-8cm). Calibrate your chrome ball
for colour by placing a white card visible in both the frame and the
reflection within the chrome ball.
THE WHITE BALL
Many VFX supervisors just shoot grey and chrome balls. Shooting a
white lighting reference ball provides additional information about
multicoloured lights.
SET UP WITNESS CAMERAS
On a miniature shoot, bring or borrow as many video cameras as you
Here’s your complete checklist of what you’ll
need to bring with you to the set. It’s a mixed
bag of handy gadgets and absolute necessities.
Some things may seem superfluous, but you’ll
be a long way from the office, and you’ll need to
be prepared for all the situations you’ve planned
for. One of your best investments will be a good
quality digital camera, capable of shooting highresolution reference stills and HDR images. Make
sure it’s able to shoot roll images in their RAW,
uncompressed format. A laser pointer is also
handy in quickly pointing out a problem in-shot,
particularly if you’re with a foreign crew and
don’t speak the same language.
can. Set up a video camera pointing at the lens of each film camera,
so you can shoot and record the speed of any zooms, particularly
when they’re not constant. It’s also good to set up a video camera
encompassing the whole of the working area on the stage. If
anything unexpected happens mid-shot, you’ll have it recorded on
tape for later reference. ●
• Digital stills camera, various lenses,
spare batteries, memory cards and a
battery charger
• Tripod and lighting flag stands
• Tracking markers
• Light meter
• Printed templates for shoot notes
• Visual effects slates and a clipboard
• Pocket-size notebook or PDA
• Sharpies, pens and pencils
• Gaffer tape and camera tape (you never know
what you might need to fix)
• Lighting reference balls: grey, chrome and
possibly white balls
• A laptop with your compositing software
of choice
• Lens grids
• Tape measure and a laser range finder
• Grey glass and various coloured filters
• Video cameras on a miniature shoot, spare
batteries and tapes
• Leatherman and scissors
• An LED torch
• A laser pointer
• An inclinometer (to measure camera tilt)
• A spirit level
• The American Cinematographer Manual
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