Study on method of Study on method of detecting preceding detecting preceding

vehiclevehicle

Study on method of Study on method of detecting preceding detecting preceding

vehiclevehicleJilin university, CHINAJilin university, CHINA

2004 IEEE CNF2004 IEEE CNF

流程圖• Detecting possible object• Measure of symmetry• Distance Detction

Character of Target Vehicle

• Gray characteristics• Boundary characteristics• Symmetry characteristics

Detecting possible object

• The triangle area is called the primary area of interesting

Detecting possible object

• G(r) is the mean value of the pixel gray on r row• rb(r) is the coordinate of pixel on right end of r row

in the primary area of interesting• lb(r) is the coordinate of pixel on left end of r row in

the primary area of interesting• g(r,c) is a gray of pixel(r,c) on r row

Detecting possible object

Detecting possible object

• P(xk) is probability of the gray value xk

Detecting possible object

Identifying area of interesting

Measure of symmetry

• w is the width of symmetry area

• xs is origin• u = x-xs

Measure of symmetry• Energy function

dxxfxfE )())(( 2

• The Energy function of even function and odd function

2/

2/

2 ),,(),(w

wusse wxuewxE

2/

2/

2 ),,(),(w

wusso wxuowxE

Measure of symmetry

2/

2/

),,(1

),,(),,(w

wvsss wxve

wwxuewxue

• Transform the even function let its mean value is also zero.

2/

2/

2 ),,(),(w

wuss wxuewxE

Measure of symmetry

• The range of symmetry measure is (-1,1)• s=1, it is a full symmetry• s=-1, it is no symmetry

• The symmetry depends on parameters xs and w

Measure of symmetry

Measure of symmetry

w

sx

s wxsn

xs

),(1

)(

Measure of symmetry

• Calculate the symmetry measure about every row in the identifying area of interesting.

• Count the mean value of symmetry measure.

Distance Detction))/)arctan((tan(/ 0 fyyhd

• f is the focus of CCD camera.

• αis the incline angle of CCD camera

• h is the height of CCD camera to ground

• (x,y) is the point P projection in image plane

Distance Detction• image plane coordinate ： millimeter, (x,y)• store frame coordinate ： pixel, (u,v)

Experiment for detecting preceding

vehicleNo Alg：•overall detection rate 90%•false alarm rate 13%•mean time of detecting object 82ms

Have Alg：•verall detection rate 94%•false alarm rate 6%•mean time of detecting object 68ms

Experiment for distance detection