The 7 Uses of Motion Control
(This is the full article previously published in parts)
Did we say 7 uses? - Well that's not quite true. There
are in fact countless. To many to list in a
newsletter in detail, but there are generally 7 main reasons
for using motion control. These categories
are listed below and we will be covering them all in greater detail.
- Repeat Moves
- Making elements appear and disappear, crowd replication,
changing backgrounds and foregrounds, filming action at different
speeds, putting elements together.
- Scaled Moves
- Shooting miniatures, rotating camera moves, matching scales.
Moves - For controlled
filming and lighting on products.
- CGI Export
- Combining live-action to CGI.
- CGI Import
- Complex moves, unusual shapes, impossible moves, Pre-visualisation.
- Frozen Moment
Integration - For mixing live-action and time-slicing
- Specific Music Video Effects> -
Audio timecode triggering.
The best known category of use is Repeat Moves
and is the basis for all motion control. A good quality motion control
system can repeat any camera movement with extreme accuracy, countless
times. Once a camera can repeat the movement a whole range of effects
can be created. One of the simplest effects is making elements
appear or disappear. This is done by filming, for
example, an empty room and then filming again with the motion
control camera but this time with an actor or some furniture in the
room. One can then take the 2 shots and easily mix between the two to
make it appear that the furniture or actor is appearing or
disappearing. Another possibility is to shoot the room again but this
time have the same actor stand in a different position. Now in the
finished shot one effectively has duplicated the actor
so there are several copies of him on the screen. What about a crowd? Crowd
replication is the same idea applied to a battle-field
or a busy street scene where one requires hundreds of actors, or
maybe identical cars or planes. Well why not take a handful of actors
or one plane and simply shoot the same scene again and again with
the actors or plane in different positions. Then when compositing it
is easy to make it look like a huge number of people or even objects
were involved. If one requires the backgound to change
instead of the foreground, one could shoot an actor on green-screen
and then use the motion control system to shoot a room and a street.
Now it becomes very simple in post-production to make it appear that
the background is changing for the actor from a room to a street.
Motion control is also used when filming animals
with other animals or humans that would otherwise be impossible to
achieve. For example, imagine creating a shot of a baby playing next
to a group of real lions. Or what about a leopard walking next to a
zebra. Additionally, where a shot can only be done with an animal
trainer controlling the animal, it is possible to shoot a "clean
pass" of the scene. Once one has a clean pass, it
is very simple and an almost automated process to remove the trainer
from the scene to only leave the animal. Because Mark
Roberts Motion Control systems are designed to be ultra
accurate, one can shoot at different film speeds
and combine the shots seamlessly. For example, one could have an actor
walking and talking at live-action while everyone around him is moving
in slow-motion or high-speed. The repeatability of the motion control
camera means you can shoot at 4FPS (frames per second) and then again
at 120FPS and when combining the two, it will be impossible to see a
join. Another area that is covered by the Repeat Moves category is
animation and mixing animation with live-action.
is more than just taking a move and changing its size, and many
different effects can be achieved using the scaling feature of Flair,
the motion control software developed by Mark Roberts Motion Control.
The simplest concept is doing just that, changing the scale,
for example it may be that a large full size set would be to costly to
build, or take too long, or it maybe that the camera movement required
would be too large to achieve with a crane, so a scale model is built
and shot using a motion control system. The software will then automatically
scale the movement up or down to then shoot again but this time with a
live actor or another differently scaled model. Because the 2 movements
are shot from exactly the same perspective, just scaled, the 2 camera
passes will match so that it appears that there has been no change. It
can be made to look like an actor is standing in a room that is much to
large for him, or on a castle even though the castle only exists as a
small scale model. These techniques are often used in feature films, in
everything from Entrapment, to Harry Potter,
to The Borrowers. In fact, in the latter, a large encoded
crane (see www.mrmoco.com
to find out more about encoded cranes) was used to shoot the actors
against bluescreen and then the recorded move data transfered to a
motion control rig, to scale and shoot again but this time with actors
in a real set. The two takes were then seamlessly composited to look
like there was a huge difference in physical size between the actors.
Scale models were also used on Moulin Rouge, which has
currently been nominated for 8 Academy Awards,
including Best Cinematography.
Another form of "scaling" is often used that does not
actually involve a difference in scale, only in position or
orientation. It is possible to tell the software to rotate the move in
any direction. For example, if one has a box and one wants to make it
appear that people are walking on many of its different sides, then
one shoots a scene with an actor walking on top of the box. Then one
shoots again but telling the motion control rig to rotate
the move by 90 degrees. Now those 2 takes can be seamlessly composited
to make it appear that one actor (or even the same actor) was walking
on 2 different sides of the box, completely defying gravity. This
trick could be done with staircases, or with rooms, of having people
walking on the walls and ceiling (as can be seen on the Showreel -
Motion Control Explained).
Controlled Moves, while being one of the simplest uses of
motion control is often most forgotten about and under-estimated. Motion
Control is most commonly used not because of some amazing special
effect, but simply because the Director and DoP want their
shot to look exactly right. They want the lighting exactly as required,
no flat spots, flares or bad reflections, and the talent doing exactly
the right action when required, and motion control saves them a
lot of time. Take a product shot for a commercial, such as a car or a
drink. Any DoP will tell you that trying to handle the
lighting on a car can be very time consuming, with all its
reflective and smooth, flat parts. The light may be right on one part of
a car and wrong on another. Now even once you have adjusted the
lighting, if the grips pushing the camera do not produce the exact same
move during every take, one can get new lens flares or reflections show
up. Additionally, even if they are perfect, if the actor or the focus
puller makes a mistake, another take has to be done, hoping the camera
move will again be the same. With motion control this whole process is
dramatically speeded up, as one simply programs in the desired move
which can then be played back over and over it different speeds,
checking the lighting at every frame. Once the lighting is right, the
camera will accurately be controlled to repeat the movement including
focus and zoom changes and it can be shot using just one take.
Additionally, in most western countries, the cost of renting a crane
with grips and focus puller is no different than a similar sized
motion control rig and operator, yet the motion control system's
capabilities are much higher, saving time and costs.
Another use of controlled moves, is when using complex lenses or even macro
lenses. For some shots, one requires a snorkel lens
(a lens with a right angle turn in it) or a long boroscope
lens, to get into very tight spots or in between scale models
(e.g. models of buildings). Controlling a camera with such lens by
hand is very complex, but by using a motion control rig, one can
program in the move very quickly and then get the shot. The move is
easily adjusted and edited to get the exact move required. Similarly,
if shooting with a macro lens, when shooting very close to an object,
all camera movements become greatly magnified. It becomes quite hard
to move a camera by hand without the shot looking unsteady, wobbly or
shakey. But a motion control rig controls the camera movement very
accurately down to fractions of millimetres, so extreme close-ups are
easy to program and shoot, and of course the lighting can also be
adjusted to suit the shot.
Frame-by-frame animation although discussed in part 1
- Repeat Moves - is also closely related to the controlled moves use
of motion control. The whole camera move is programmed into the motion
control rig, and all the focus and lighting adjusted as one continous
move before shooting the scene using stop-frame animation.
CGI Export is the term given to any move data that is
transfered from a motion control camera to 3D CGI
(Computer Generated Images) software. Because the Flair
motion control software knows the exact 3D position of the camera at any
point, both in real-time and with a sub-millimetre accuracy, it is very
simple to export this data (sometimes refered to as XYZ data)
to CGI to add computer graphics background or foreground elements. The
data is read by a huge variety of software packages, including Softimage,
XSi, Maya, Flame, Lightwave, Inferno etc. and because the data
is very accurate, the Flair software taking account of
different lenses and the effects of focussing, 3D elements are much more
easily and accurately added than any other method.
Mark Roberts Motion Control is the only company in
the world to design and create all the parts of a motion control
system, including the mechanics and the software. This means that
features have been built into the Flair software that are not possible
on any other system. It has such an accurate model of the mechanics
that it also gets used for real-time applications such as Virtual
Studios or on-the-set graphics previews, where the CGI
elements are added in real-time to the live video footage, according
to the real-time XYZ data from Flair.
One could film an actor in a live set and use the CGI export data to
add foreground elements for the actor to interact with, or one could
additional background elements. Adding additional background elements
is sometimes refered to as digital matte painting,
where a graphics artist creates a model of scenes in the distance that
don't require as much detail as the scenes shot with a camera in the
foreground. This is often used for feature films, such as Gladiator,
A Knight's Tale, or Star Wars,
where a live scene is filmed, sometimes using a scale model, and then
the background is changed to have some amazing city, skyline, or
mountain in the background, and because the camera XYZ's are known
precisely, once the digital matte painting is created,
adding it with the right scale and perspective is easy.
When exporting CGI data, motion control moves do not have to be
pre-programmed. One may need to accurately follow an actor or an
animal, or the director may want a very erratic, "human" or
steady-cam looking move, and these are all easily done using remote handwheels
or the popular Grip-Sticks which allow a Director of
Photography to simply push the motion control camera by hand, as if it
were hand-held or on a crane, all the while recording the movement and
the camera position for exporting to CGI.
With the rapidly increased use of computer graphics for
planning and storyboarding of productions, and on the actual set
during the production, the use of interfacing motion control with CGI
has grown dramatically.
CGI Import is the term given
to any move data that is transferred from 3D CGI
(Computer Generated Images) software to a motion control camera.
Because the Flair motion control software has a very
accurate Inverse-Kinematics model of the rig moving
the camera, including the exact parameters of the optical lens, it is
very simple for it to move the camera to any 3D position in space
(referred to as XYZ position).
Effectively, one can plan and storyboard
a whole shot in software packages such as Softimage(tm)
or Maya(tm), and then arrive on set and have the
camera achieve the exact same shot. Because moves have been created in
a graphics environment, complex effects can be achieved. Additionally,
because everything about the shot is known beforehand, less waste is
achieved on set (by not building oversize sets or backgrounds, only
getting the exact lights and grip equipment required, having less
planning and unknowns occurring on-set) thereby reducing actual
This whole action of pre-planning moves is referred
to as Pre-visualisation, and is becoming common place
on large feature film productions as well as commercials and music
Pictures courtesy of Pixel Liberation Front
The Panic Room is one of many
recent productions, including Harry Potter, K19, Dinotopia,
Black Hawk Down, and Spiderman, that makes
heavy use of pre-visualisation. Using Softimage|XSI, Pixel
Liberation Front managed to create an animated CG version of the
105-page script of Panic Room for David Fincher's
latest Columbia Tri-Star movie. It was used as the primary animation
tool to pre-visualize the entire set, camera positionings and
movements, as well as character moves, in order to facilitate the
actual shoot and production of the film. It was a creative tool for
Fincher and it provided an enormous amount of detailed technical, and
pre-production information for every aspect of making the movie - from
art direction to music scoring to set construction.
Ron Frankel, PLFs previsualization
David Finchers goal was to produce
a coherent 3-D animated and edited cut of the film before the shooting
even began. The scenes we created with XSI included the set,
characters, key props and set dressing. We were able to animate the
scenes with XSI to indicate both character blocking and camera
movement, giving a sense of how individual shots would look before
they were filmed and how they would be edited together into a
sequence. The 3-D scenes were highly interactive, allowing film
director David Fincher to refine actor blocking, timing, camera
position and other factors, and immediately see the results. The
animation was also used to derive a wealth of information relative to
set construction, camera equipment needs, set dressing and so forth,
making it an invaluable asset to the production crew. This saved time
and money that would otherwise have been spent on set configuration,
camera placement and rehearsals.
Motion control can be used to match camera array
shots. Camera Array shots are also known as frozen moment
or time-slicing or bullet-time (made famous in The
Matrix). Because the camera array represents a moving camera path
the same path can be defined in a motion control move. This
allows all of the other effects that are possible with motion control
to be combined with frozen moments. For example, a live action
pass filmed with motion control allows for the insertion of a moving
person into a frozen scene.
Motion control can also be used to get into and out
of frozen moment shots seamlessly. A camera move can begin with
a motion control move and switch at some point to the camera array.
The motion control system moves the motion picture camerašs position
from a start position to the first position of the camera array, at
which point the camera array is triggered. In post production a
straight cut joins the two shots. Dayton Tayloršs company,
Digital Air (http://www.virtualcamera.com),
has produced a special Arri mount lens with a mirror in front of it
that allows a motion picture camerašs point of view to connect with
his Timetrack camera without the two cameras crashing into each other
at the transition point.
Because frozen moment shots often use interpolation
to create in-between frames, the number of cameras in the array does
not necessarily equal the number of frames in the final shot.
Interpolation is used to overcome camera spacing limitations.
Frames can be interpolated that appear to have been recorded from
camera positions between the actual cameras. When integrating camera
array shots with motion control, scenes can be designed that take this
into account. For example, even a small (ten camera) array can produce
a significant spatial perspective shift. If the ten camera array
shot is interpolated to sixty frames then the corresponding match move
motion control shot should record all sixty frames, not just the ten
frames that match the camera arrayšs individual camera positions.
This is particularly useful because it allows interpolation to be used
only on the elements which require it and motion control can be used
to produce the footage of the other elements in the shot such as
background and moving elements.
The photos below show Digital Air's camera array
being used with the Milo motion control rig, for a Schweppes
commercial. Director Jon Hollis from Smoke and Mirrors, London, used
Timetrack cameras for product shots and a Milo for matched moves of
the background, which included the commercial's main character, a
Specific Music Video Effects - Audio Timecode Triggering
Motion Control in shooting music videos (promos) is not as such a
separate use of motion
control. Unlike the earlier mentioned uses of motion control, it is
not used to achieve
something that was previously impossible or difficult, rather it
uses the previous uses of motion
control together with timecode to achieve the effects specifically
in synchronization to sound. It
is noted not because it allows motion control to achieve a new type
of effect, but simply
because triggering to audio or video timecode allows the normal uses
of motion control to be
incorporated into music promo productions.
By feeding the audio timecode into the motion control software to
trigger the start (or any part)
of the moco rig's movement, it becomes very simple to create and
join film footage to audio
sound-track in a repeatable and synchronized manner.
Then all the features of the Flair software come into play, such as
scaling, actor replication,
repeat moves, varying shooting speeds etc.
One clever use of Motion Control with timecode triggering is a music
video by Kylie Minogue
"Come Into My World" which was shot by Michael Gondry using a Milo
which was placed in
the centre of a road junction and made to rotate around and around.
It was made to repeat the
same move again 3 times all synchronized to music so that by the end
of compositing there
are 4 Kylie Minogue's walking and singing together through the
Four Kylie Minogue's interacting using Timecode Synchronisation.
A similar in-studio effect is achieved in the recent award winning
Outkast video "Hey - Ya"
Another example is where very fast camera moves are required and the
speed of the timecode
is actually slowed down during shooting. When the footage is then
played back the actors
appear to be singing in realtime but the camera motions around them
are extremely fast.
Outkast's Love Below Promo