<s>
Video	B-Operating_System
tracking	I-Operating_System
is	O
the	O
process	O
of	O
locating	O
a	O
moving	O
object	O
(	O
or	O
multiple	O
objects	O
)	O
over	O
time	O
using	O
a	O
camera	O
.	O
</s>
<s>
It	O
has	O
a	O
variety	O
of	O
uses	O
,	O
some	O
of	O
which	O
are	O
:	O
human-computer	O
interaction	O
,	O
security	O
and	O
surveillance	O
,	O
video	O
communication	O
and	O
compression	O
,	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
traffic	O
control	O
,	O
medical	O
imaging	O
and	O
video	O
editing	O
.	O
</s>
<s>
Video	B-Operating_System
tracking	I-Operating_System
can	O
be	O
a	O
time-consuming	O
process	O
due	O
to	O
the	O
amount	O
of	O
data	O
that	O
is	O
contained	O
in	O
video	O
.	O
</s>
<s>
The	O
objective	O
of	O
video	B-Operating_System
tracking	I-Operating_System
is	O
to	O
associate	O
target	O
objects	O
in	O
consecutive	O
video	O
frames	O
.	O
</s>
<s>
For	O
these	O
situations	O
video	B-Operating_System
tracking	I-Operating_System
systems	O
usually	O
employ	O
a	O
motion	O
model	O
which	O
describes	O
how	O
the	O
image	O
of	O
the	O
target	O
might	O
change	O
for	O
different	O
possible	O
motions	O
of	O
the	O
object	O
.	O
</s>
<s>
When	O
tracking	O
planar	O
objects	O
,	O
the	O
motion	O
model	O
is	O
a	O
2D	O
transformation	O
(	O
affine	B-Algorithm
transformation	I-Algorithm
or	O
homography	B-Algorithm
)	O
of	O
an	O
image	O
of	O
the	O
object	O
(	O
e.g.	O
</s>
<s>
For	O
video	O
compression	O
,	O
key	O
frames	O
are	O
divided	O
into	O
macroblocks	B-General_Concept
.	O
</s>
<s>
The	O
motion	O
model	O
is	O
a	O
disruption	O
of	O
a	O
key	O
frame	O
,	O
where	O
each	O
macroblock	B-General_Concept
is	O
translated	O
by	O
a	O
motion	O
vector	O
given	O
by	O
the	O
motion	O
parameters	O
.	O
</s>
<s>
To	O
perform	O
video	B-Operating_System
tracking	I-Operating_System
an	O
algorithm	O
analyzes	O
sequential	O
video	O
frames	O
and	O
outputs	O
the	O
movement	O
of	O
targets	O
between	O
the	O
frames	O
.	O
</s>
<s>
There	O
are	O
two	O
major	O
components	O
of	O
a	O
visual	B-Operating_System
tracking	I-Operating_System
system	O
:	O
target	O
representation	O
and	O
localization	O
,	O
as	O
well	O
as	O
filtering	O
and	O
data	O
association	O
.	O
</s>
<s>
Kernel-based	O
tracking	O
(	O
mean-shift	B-Algorithm
tracking	O
)	O
:	O
an	O
iterative	O
localization	O
procedure	O
based	O
on	O
the	O
maximization	O
of	O
a	O
similarity	O
measure	O
(	O
Bhattacharyya	O
coefficient	O
)	O
.	O
</s>
<s>
active	O
contours	O
or	O
Condensation	B-General_Concept
algorithm	I-General_Concept
)	O
.	O
</s>
<s>
Particle	B-Algorithm
filter	I-Algorithm
:	O
useful	O
for	O
sampling	O
the	O
underlying	O
state-space	O
distribution	O
of	O
nonlinear	O
and	O
non-Gaussian	O
processes	O
.	O
</s>
