Figure
Chromak
ey
T
ec
hnology
tak
es
form
during
the
ev
ening
w
eather
telecasts
Fig
where
c
hromak
ey
tec
h
nology
allo
ws
actors
to
b
e
placed
in
a
scene
through
the
use
of
a
blue
screen
By
replacing
the
blue
bac
k
drop
with
a
video
image
a
p
erson
can
b
e
situated
an
ywhere
This
tec
hnology
do
esn t
allo
w
for
m
uc
h
in
teraction
though
as
the
actor
sees
only
the
blue
screen
and
m
ust
observ
e
an
o camera
monitor
to
see
himself
as
immersed
Early
uses
of
non con
tact
in
terfaces
date
bac
k
to
the
s
with
the
w
ork
of
Leon
Theremin Cha
His
use
of
capacitance
pro
ximit
y
sensing
as
a
m
usical
instrumen
t
w
as
the
earliest
electronic
free
gesture
device
More
recen
tly
other
t
yp
es
of
non
con
tact
sensing
ha
v
e
b
een
applied
to
HCI
applications
in
The
Br
ain
Op
er
a
Wil
a
large
scale
in
teractiv
e
m
usic
pro
ject
dev
elop
ed
at
the
MIT
Media
Lab
The
sensing
systems
v
aried
from
sonars
and
radars
to
electric
eld
sensors P
ar
Electric
Field