Adaption of Unscen
ted Particle filter for Visual
tracking in Electro-Optic Theodolite
R
ongtai Cai, Rui Zhang ,Qingxiang Wu
Coll
ege of Photonic and Electronic Engineering,
Fujian Normal University
Fuzhou, 350108, China
{gjrtcai, qxwu}@163.com
Honghai Sun
Changchu
n Institute of Optics, Fine Mechanics and
Physics,
Chinese Academy of Science
Changchun, 130033, China
{HHSun }@ciomp.ac.cn
Abstra
ct—To satisfy the need of visual tracking in electro-optic
theodolite, we use some simplification technology to adapt UPF
(Unscented Particle Filter), which reduce the computational
complexity considerably. The state space equation in electro-
optic theodolite tracking system is linear; the sigma sampling
in unscented transform can be simplified as a decomposition-
composition process; the nonlinear transmit of sigma sampling,
state vector, measurement vector and their covariance matrix
are simplified by an MSUPF (UPF for Mixture system)
algorithm. Experiment result shows that the proposed
algorithm has better calculation accuracy with considerable
lower computational complexity compare with UPF. The
computation work of the proposed algorithm is only 81.13% of
that of the UPF.
Keywords- particle filter; unscented particle filter; visual
tracking; object tracking
I
.
I
N
TRODUCTION
As
we know, the academic society and the industry
society are considering different aspect of an algorithm. So
the adaptation of an algorithm derives from academic society
to satisfy the need of industry application is an important
topic
[
1]
.
Bay
esian filter based algorithm is one kind of important
methods in visual tracking, especially the Particle filters (PFs)
[2]
which have
large spectrum of applications in visual
tracking. But the PFs in academic society are not cut into the
industry shape. So we adapt the traditional PFs in academy
society to satisfy the need of the industry application.
II. M
OTIO
N
M
ODEL
F
OR
T
RA
CKED
O
BJECT
In
simple visual tracking applications, the location of
tracked object is recorded with X-axis and Y-axis in
orthogonal coordinates, but the location of tracked object in
electro-optic theodolite system is recorded with angle of
orientation, angle of pitch and radial distance in spherical
coordinates.
Suppose that the tracked object is moving in a smooth
trajectory, the motion trace can be described with a
polynomial curve. Specifically, a second order polynomial is
employed to describe the motion trace of the tracked object.
In orthogonal coordinates, that is
2
0 1 2
x
,
(1)
2
0 1 2
y
,
(2)
2
0 1 2
z
,
(3)
where x(t), y(t) and z(t) is the position of the object in x-axis,
y-axis, and z-axis respectively; n
x
(t),
n
y
(t)
and n
z
(t) are
noise
respectively
[
3]
.
Acc
ording to (1), (2) and (3), the state equation of the
tracked object is
x
x Ax n
(4)
where
( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
T
k x k x k x k y k y k y k z k z k z k
x
is th
e state parameters,
, , , , , , , ,x x x y y y z z z
are
position,
speed and acceleration components in x-axis, y-axis and z-
axis respectively.
A
is state transition matrix:
1 1 1
2 2 2
1 1 1
0 1 0 1 0 1
0 0 1 0 0 1 0 0 1
T T T T T T
T T T
A
, T
is the
sampling period, And suppose that
n
x
(k)
is Gaussian white
noise with zero-mean. k is time variable. The correlation
matrix of the noise is defined by
nx xx
k diag
R
,
where
is corr
elation coefficient of noise.
According to the relationship of spherical coordinates
and rectangular coordinates, the measurement equation is
2 2
2 2 2
( )
( )
( )
( ) ( )
( ) ( ) ( ) ( ) ( )
( ) arctan ( )
( ) ( )
arctan
R
y k
V
x k
z k
H
x k y k
R k x k y k z k n k
V k n k
H k n k
, (5)
where x(k), y(k)and z(k) are position components in x-axis,
y-axis and z-axis respectively, R(k),V(k) and H(k) are radial
distance, azimuth angle and elevation angle respectively,
n
R
(t), n
V
(t) and n
H
(t) are noise in radial distance, azimuth
angle and elevation angle respectively.
For conciseness, (5) can be written as
y
( ) [ ( ), ] ( )k h k k k
z x n
,
(6)