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Tracking H akan Ard o March 4, 2013 H akan Ard o Tracking - - PowerPoint PPT Presentation

Introduction Tracking with static camera Tracking with moving camera Tracking H akan Ard o March 4, 2013 H akan Ard o Tracking March 4, 2013 1 / 57 Introduction Tracking with static camera Tracking with moving camera State


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SLIDE 1

Introduction Tracking with static camera Tracking with moving camera

Tracking

H˚ akan Ard¨

  • March 4, 2013

H˚ akan Ard¨

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SLIDE 2

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

Outline

1

Introduction State space Sliding Window Detection

2

Tracking with static camera Greedy Kalman filter Particle filter

3

Tracking with moving camera Self-motion

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SLIDE 3

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

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SLIDE 4

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

H˚ akan Ard¨

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SLIDE 5

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

H˚ akan Ard¨

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SLIDE 6

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

H˚ akan Ard¨

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SLIDE 7

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

H˚ akan Ard¨

  • Tracking

March 4, 2013 3 / 57

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SLIDE 8

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

State space

State: position X = (X, Y , Z, 1), velocity, v = (vx, vy, vz, 0), ... Observation: detection in image x = (x, y, 1) Observation model: λx = PX Dynamic model: Xt+1 = Xt + vt and vt+1 = vt Sthocastic dynamic model: Introduce noise, random numbers q and w Xt+1 = Xt + vt + q vt+1 = vt + w Sthocastic observation model: Introduce noise, a random number r λx = PX + r

H˚ akan Ard¨

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SLIDE 9

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

Sliding window detectors

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SLIDE 10

Introduction Tracking with static camera Tracking with moving camera State space Sliding Window Detection

Detection probability

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SLIDE 11

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Greedy tracker

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SLIDE 12

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 1

STC Lecture Series An Introduction to the Kalman Filter

Greg Welch and Gary Bishop

University of North Carolina at Chapel Hill Department of Computer Science

http://www.cs.unc.edu/~welch/kalmanLinks.html

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SLIDE 13

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Sanjay Patil1 and Ryan Irwin2 Graduate research assistant1, REU undergrad2 Human and Systems Engineering

URL: www.isip.msstate.edu/publications/seminars/msstate/2005/particle/

HUMAN AND SYSTEMS ENGINEERING:

Gentle Introduction to Particle Filtering

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SLIDE 14

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 5

Some Intuition

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SLIDE 15

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 6

First Estimate

ˆ x

1 = z1

ˆ σ

2 1 = σ 2 z1

Conditional Density Function

14 12 10 8 6 4 2

  • 2

N(z1,σz1

2 )

z1 σ 2

z1

,

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SLIDE 16

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 7

Second Estimate

Conditional Density Function

z2 σ 2

z2

,

ˆ x

2 =...?

ˆ σ

2 2 = ...?

14 12 10 8 6 4 2

  • 2

N(z2,σz2

2 )

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SLIDE 17

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 8

Combine Estimates

= σ z2

2

σ z1

2 + σ z2 2

( )

[ ]z1+ σ z1

2

σ z1

2 + σ z2 2

( )

[ ]z2

ˆ

x

2

= ˆ x

1 + K2 z2 − ˆ

x

1

[ ]

where

K2 = σ z1

2

σ z1

2 + σ z2 2

( )

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SLIDE 18

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 9

Combine Variances

1 σ 2 = 1 σ z1

2

( )+ 1 σ z2

2

( )

2

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SLIDE 19

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 10

Combined Estimate Density

ˆ x = ˆ σ

2 = σ 2

2

ˆ

x

2

14 12 10 8 6 4 2

  • 2

Conditional Density Function N( σ 2)

ˆ

x,ˆ

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SLIDE 20

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 11

Add Dynamics dx/dt = v + w

where v is the nominal velocity w is a noise term (uncertainty)

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SLIDE 21

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 7 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering algorithm step-by-step (1)

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SLIDE 22

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 8 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering step-by-step (2)

H˚ akan Ard¨

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SLIDE 23

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 9 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering step-by-step (3)

H˚ akan Ard¨

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SLIDE 24

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 10 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering step-by-step (4)

H˚ akan Ard¨

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SLIDE 25

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 11 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering step-by-step (5)

H˚ akan Ard¨

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SLIDE 26

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Page 12 of 20 Particle Filtering – Gentle Introduction and Implementation Demo

Particle filtering step-by-step (6)

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SLIDE 27

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 13

Some Details

x x A A x x w w z z H H x x . . . . . . . . = + =

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SLIDE 28

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 14

Discrete Kalman Filter

Maintains first two statistical moments

process state (mean) error covariance z y x

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SLIDE 29

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 16

Necessary Models

measurement model dynamic model

previous state next state state measurement

image plane

( u , v )

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SLIDE 30

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 17

The Process Model

x k+1 = Axk + wk zk = Hxk + vk

Process Dynamics Measurement

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SLIDE 31

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 18

Process Dynamics

x k+1 = Axk + wk

xk ∈ Rn contains the states of the process

state vector

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SLIDE 32

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 19

Process Dynamics

nxn matrix A relates state at time step k to time step k+1

state transition matrix

x k+1 = Axk + wk

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SLIDE 33

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 20

Process Dynamics process noise

wk ∈ Rn models the uncertainty of the process wk ~ N(0, Q)

x k+1 = Axk + wk

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SLIDE 34

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 21

Measurement

zk = Hxk + vk

zk ∈ Rm is the process measurement

measurement vector

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SLIDE 35

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 22

Measurement

zk = Hxk + vk

state vector

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SLIDE 36

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 23

Measurement

mxn matrix H relates state to measurement

measurement matrix

zk = Hxk + vk

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SLIDE 37

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 24

Measurement measurement noise

zk ∈ Rm models the noise in the measurement vk ~ N(0, R)

zk = Hxk + vk

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SLIDE 38

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 25

State Estimates

a priori state estimate a posteriori state estimate

ˆ x –

k

ˆ xk

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SLIDE 39

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 26

Estimate Covariances

a priori estimate error covariance a posteriori estimate error covariance

Pk

– = E[(xk- xk –)(xk - xk –)T]

ˆ ˆ

Pk = E[(xk- xk)(xk - xk)T]

ˆ ˆ

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SLIDE 40

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 27

Filter Operation

Time update (a priori estimates) Measurement update (a posteriori estimates)

Project state and covariance forward to next time step, i.e. predict Update with a (noisy) measurement

  • f the process, i.e. correct

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slide-41
SLIDE 41

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 28

Time Update (Predict)

state error covariance

H˚ akan Ard¨

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slide-42
SLIDE 42

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 29

Measurement Update (Correct)

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slide-43
SLIDE 43

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 30

Time Update (Predict)

a priori state and error covariance

ˆ

xk+1 = Axk

Pk+1 = APk A + Q

H˚ akan Ard¨

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SLIDE 44

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 31

Measurement Update (Correct)

a posteriori state and error covariance Kalman gain

ˆ

xk = xk + Kk (zk - Hxk )

ˆ ˆ

– –

Pk = (I - Kk H)Pk

Kk = Pk HT(HPk HT + R)-1

– –

H˚ akan Ard¨

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slide-45
SLIDE 45

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

UNC Chapel Hill Computer Science Slide 32

Filter Operation

Time Update (Predict) Measurement (Correct) Update

H˚ akan Ard¨

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SLIDE 46

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Kalman filter tracker

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SLIDE 47

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Kalman filter tracker

H˚ akan Ard¨

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SLIDE 48

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Kalman filter tracker

H˚ akan Ard¨

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SLIDE 49

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Kalman filter tracker

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SLIDE 50

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter

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SLIDE 51

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Patricle filter states

Current state

  • x(1)

k , x(2) k , x(3) k , · · · , x(n) k

  • Predicted state (a priori state extimate)
  • x−(1)

k+1 , x−(2) k+1 , x−(3) k+1 , · · · , x−(n) k+1

  • Corrected state (a posteriori state extimate)
  • x(1)

k+1, x(2) k+1, x(3) k+1, · · · , x(n) k+1

akan Ard¨

  • Tracking

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slide-52
SLIDE 52

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Patricle filter states

Current state

  • x(1)

k , x(2) k , x(3) k , · · · , x(n) k

  • Predicted state (a priori state extimate)
  • x−(1)

k+1 , x−(2) k+1 , x−(3) k+1 , · · · , x−(n) k+1

  • Corrected state (a posteriori state extimate)
  • x(1)

k+1, x(2) k+1, x(3) k+1, · · · , x(n) k+1

akan Ard¨

  • Tracking

March 4, 2013 46 / 57

slide-53
SLIDE 53

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Patricle filter states

Current state

  • x(1)

k , x(2) k , x(3) k , · · · , x(n) k

  • Predicted state (a priori state extimate)
  • x−(1)

k+1 , x−(2) k+1 , x−(3) k+1 , · · · , x−(n) k+1

  • Corrected state (a posteriori state extimate)
  • x(1)

k+1, x(2) k+1, x(3) k+1, · · · , x(n) k+1

akan Ard¨

  • Tracking

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slide-54
SLIDE 54

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Dynamic model

Any sthocastic model from which we can sample f (xk+1 |xk ) Example: The dynamic model from the kalman filter xk+1 = Axk + wk f (xk+1 |xk ) = N(Axk, Q)

H˚ akan Ard¨

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slide-55
SLIDE 55

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Dynamic model

Any sthocastic model from which we can sample f (xk+1 |xk ) Example: The dynamic model from the kalman filter xk+1 = Axk + wk f (xk+1 |xk ) = N(Axk, Q)

H˚ akan Ard¨

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slide-56
SLIDE 56

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter prediction step

Propagate each particle i, separately The prediction x−(i)

k+1 is choosen as a sample from

f

  • xk+1
  • x(i)

k

akan Ard¨

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slide-57
SLIDE 57

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Measurement model

Any sthocastic model from which we can calculate likelihoods f (zk |xk ) Example: The measurement model from the kalman filter zk = Hxk + vk f (zk |xk ) = N(Hxk, R)

H˚ akan Ard¨

  • Tracking

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slide-58
SLIDE 58

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Measurement model

Any sthocastic model from which we can calculate likelihoods f (zk |xk ) Example: The measurement model from the kalman filter zk = Hxk + vk f (zk |xk ) = N(Hxk, R)

H˚ akan Ard¨

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slide-59
SLIDE 59

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter correction step

The measurement model gives a weight for each particle, i w(i)

k

= f

  • zk
  • x−(i)

k

  • Resample the set of particles using the weights

Each corrected particle, x(i)

k , is choosen randomly

x(i)

k

= x−(j)

k

for some random j The probability of choosing sample j is w(j)

k

  • l w(l)

k

The same particle may be choosen several times

H˚ akan Ard¨

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slide-60
SLIDE 60

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter correction step

The measurement model gives a weight for each particle, i w(i)

k

= f

  • zk
  • x−(i)

k

  • Resample the set of particles using the weights

Each corrected particle, x(i)

k , is choosen randomly

x(i)

k

= x−(j)

k

for some random j The probability of choosing sample j is w(j)

k

  • l w(l)

k

The same particle may be choosen several times

H˚ akan Ard¨

  • Tracking

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slide-61
SLIDE 61

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter correction step

The measurement model gives a weight for each particle, i w(i)

k

= f

  • zk
  • x−(i)

k

  • Resample the set of particles using the weights

Each corrected particle, x(i)

k , is choosen randomly

x(i)

k

= x−(j)

k

for some random j The probability of choosing sample j is w(j)

k

  • l w(l)

k

The same particle may be choosen several times

H˚ akan Ard¨

  • Tracking

March 4, 2013 50 / 57

slide-62
SLIDE 62

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter correction step

The measurement model gives a weight for each particle, i w(i)

k

= f

  • zk
  • x−(i)

k

  • Resample the set of particles using the weights

Each corrected particle, x(i)

k , is choosen randomly

x(i)

k

= x−(j)

k

for some random j The probability of choosing sample j is w(j)

k

  • l w(l)

k

The same particle may be choosen several times

H˚ akan Ard¨

  • Tracking

March 4, 2013 50 / 57

slide-63
SLIDE 63

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter correction step

The measurement model gives a weight for each particle, i w(i)

k

= f

  • zk
  • x−(i)

k

  • Resample the set of particles using the weights

Each corrected particle, x(i)

k , is choosen randomly

x(i)

k

= x−(j)

k

for some random j The probability of choosing sample j is w(j)

k

  • l w(l)

k

The same particle may be choosen several times

H˚ akan Ard¨

  • Tracking

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slide-64
SLIDE 64

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter

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SLIDE 65

Introduction Tracking with static camera Tracking with moving camera Greedy Kalman filter Particle filter

Particle filter tracker

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slide-66
SLIDE 66

Introduction Tracking with static camera Tracking with moving camera Self-motion

Recording sport events

H˚ akan Ard¨

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slide-67
SLIDE 67

Introduction Tracking with static camera Tracking with moving camera Self-motion

Self-motion

Detect keypoints Track each keypoint separately Use RANSAC to find camera motion Compensate for camera motion (stiching)

H˚ akan Ard¨

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slide-68
SLIDE 68

Introduction Tracking with static camera Tracking with moving camera Self-motion

Self-motion

H˚ akan Ard¨

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slide-69
SLIDE 69

Introduction Tracking with static camera Tracking with moving camera Self-motion

Self-motion

H˚ akan Ard¨

  • Tracking

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slide-70
SLIDE 70

Introduction Tracking with static camera Tracking with moving camera Self-motion

Master Thesis: Automatisk inspelning av sport

Detta projekt syftar till att utveckla mjukvara som automatiskt kan filma, f¨

  • lja och m¨

ata tider f¨

  • r ett idrottsevenemang, till exempel ett 100m-lopp i
  • friidrott. F¨
  • r detta kr¨

avs dels kunskaper i matematisk bildanalys, men en del kunskaper i programmering kommer ¨ aven att beh¨

  • vas. Vi f˚

ar hj¨ alp av IFK Lund att spela in film och utv¨ ardera resultatet. Ett examensarbete syftar till att utveckla algoritmer f¨

  • r automatisk

  • ljning av lopp. Fr˚

an b¨

  • rjan ¨

ar kameran stilla och efter starten skall den hela tiden f¨

  • lja l¨
  • parna genom att rotera och zooma. Algortimen

m˚ aste kunna kompensera och den egna kamerar¨

  • relsen.

Ytterligare ett examensarbete behandlar automatisk detektion av l¨

  • parbanan. Genom kamerakalibrering och banans k¨

anda m˚ att kan l¨

  • parnas hastighet ber¨

aknas och diagram ¨

  • ver hur hastigheten

andrats genom loppet presenteras f¨

  • r publik och tr¨
  • anare. Denna

information efterfr˚ agas av aktiva l¨

  • pare. Automatisk detektion av

m˚ allinje ¨ ar ¨ aven viktigt f¨

  • r tidtagningen ovan.

Contact: Petter Strandmark <petter@maths.lth.se>

H˚ akan Ard¨

  • Tracking

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