In Broadcast - July 2016 - 32


32

www.inbroadcast.com | Vol: 6 - Issue 7 | July 2016

InStudio

Why Mo-Sys StarTracker
Could Be The Winning Virtual
Studio Technology
M

o-Sys' StarTracker in-studio
tracking system was recently
used again by the BBC, writes
Mel Noonan, this time on the EU
referendum, making it the fifth time
that the technology has been used in
election programming by the BBC, the
previous being in the local and general
election coverage.
While establishing this standard for
high profile virtual studio election
programmes at the BBC, StarTracker
technology is also gaining popularity
with
international
broadcasters.
Michael Geissler, Mo-Sys CEO says:
"StarTracker is consistently being
chosen above older technology from
the competition, as it brings a muchneeded
state-of-the-art
tracking
solution to those wanting to reach
a new level of virtual production
capability in the broadcast industry."
System Development
Let's look back at how StarTracker
has changed the way of working in
virtual studios.
The system that is closest to
StarTracker is Free-D that was initially
developed by the BBC, and the
Lightcraft system that uses tracking
technology from Intersense. They both
employ an upwards looking camera
finding its bearing by way of circular
barcode plates.
Geissler says: "Free-D was the best of
in-studio camera tracking for its time,
but it came to market 15 years ago.
Sadly it did not reach its real potential
popularity due to having a complex set
up, and its barcodes placed limitations
on lighting.
Mo-Sys retro-reflective star sticker

"StarTracker removed these
limitations, making setup fast
and simple, and removing the
lighting restrictions. At the same
time, the system retains the
unsupervised nature of these
systems - not requiring any dayto-day calibrating, operating, or
changes in workflow - it is a true
'set up and forget' solution."
Target Tracking
The
main
characteristics
of StarTracker are flexibility,
simplified setup, unrestricted
lighting, and uncompromised
accuracy. StarTracker brings
unparalleled flexibility as a
universal solution, whether on a
large crane, small jib, pedestal or
hand-held. From small rooms with few
lights to arena-sized studios covered
with moving spotlights and LED
screens, StarTracker will still be able
to track.
The simplified setup comes from
elimination of cumbersome targets
and automatic surveying of its
'stars'. With systems based on older
technology, targets had to be large
because the camera needed to see the
position and identify several targets to
be able to track. On high ceilings this
meant many targets with diameters
20 cm or more. Each target needed
to be mounted on a separate rigid
substructure that was often a scaffold
or aluminium pole coming down from
the ceiling and lighting grid. The
presence of air conditioning ducts,
pipes and machinery complicated this.
Star Characteristics
StarTracker utilises a system that
does not require barcodes or other
identifying marks to know which target
is which. StarTracker technology takes
the identification of the target from its
constellation - its position relative to
the other stars. The lack of identifying
marks allowed the stars to be made
very small and light, negating the
need for special mounting hardware
- the stars are now stickers instead of
plates. A permanent set up with small

number of targets that can be
applied and seen unobstructed
in any given position. In contrast,
StarTracker's small stickers can
be applied in abundance, and
have a higher chance of being
seen among the multitude of
lights and structures. In a midsize studio there can easily be
500 to 1000 stickers, all placed
by a worker with a crane or
ladder in a day.
Target Calibration
Surveying the 3D positions
of these stickers in space
would be a daunting task to
do manually. Systems prior to
StarTracker often required the
StarTracker mounted to Steadicam in green position of every target needed
screen environment to be measured with surveying
stickers was suddenly achievable in techniques. It would take hours to days
hours rather than days.
to measure the exact position of each
Geissler says: "The large size of the target.
targets of previous systems restricted
StarTracker uses an automated
the hanging of lighting fixtures. The smart surveying technique to build
lighting director was restricted to place up the 3D positions of the randomly
lights out of the way of the targets. placed stars as it is moved around the
Often the area above the camera was studio. The star map is referenced to
taken up by targets, leaving the outer the real world via a simple one-time
edge of the studio as the only place to calibration where the tracking unit
hang lights. Lighting directors do not is placed in three known positions
want to compromise and be restricted to define the real-world floor and
in where they can hang their lights."
map axes. From there on the system
The StarTracker stickers are so will find its position and track
small that they can be randomly stuck automatically from power on.
in abundance above or below any
Geissler concludes: "It is clear
lighting fixture, including on metal that StarTracker has overcome the
frames and air-conducts. Because limitations of earlier systems and is
of their size there can be so many offering the ultimate easy to use and
stickers that there are always enough most effective virtual studio system
for tracking even if some are occluded available today."
by lights or structures. The result
is that there is no restriction for
the lighting director and lights
can be hung according to creative
choices rather than technical
requirements.
The density of targets directly
affects the tracking accuracy.
The more targets are in view by
the tracking camera the more
accurate the tracking will be.
The competitors' need for large
Encoded target disks used by earlier systems
barcoded targets limits the
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