Information Technology Reference
In-Depth Information
3.2 Evaluation Metrics
Success Frame Numbers (SFN).
Success frame numbers is the number of
successfully tracked frames in a video sequence [19]. A success is defined if the
overlap ratio of a tracked region and the ground truth is higher than a predefined
threshold
ʸ
.Hereweuse
ʸ
=0
.
5.
N
SFN
ʸ
=
1
N
ʴ
(
O
tracked
i
≥
ʸ
)
,
(6)
i
=1
where
O
tracke
i
is the overlap ratio of tracked region in frame
i
and
ʸ
is predefined
threshold. The higher the successful number, the better the performance of the
method.
The comparison between our proposed method, STRUCK [1] and TLD [2] in
terms of SFN shown in Table 2. From the results, we know that our proposed
method outperforms the other two approaches in the Diving video.
Tabl e 2.
Performance comparisons (ratio) of different object tracking approaches in
terms of SFN
STRUCK [1] TLD [2] Proposed Method
Crossing
0.48
0.42
0.38
Diving 0.7
0
0.49
Ironman
0.6
0.5
0.2
Accumulated Center Location Error (ACE).
ACE use to measure the
center location (
CE
i
) distance between the center location of the ground truth
and tracker [20]. The formulation is as follows:
N
f
i
1
ACE
=
CE
i
,
(7)
where
N
is the number of frames and
f
i
is the
i
th
frame. The lower the center
location error, the better the performance of the tracker.
The comparison between our proposed method, STRUCK [1] and TLD [2] in
terms of ACE shown in Table 3. The average ACE from our proposed method
is lower than the other two methods in the Crossing and Diving video. It means
that our proposed method works better with the minimum error number.
Overlap Ratio.
Overlap ratio is the percentage of overlapping area between
ground truth and tracked region in frame [20].
area
defines the total number of
pixels which overlapping between ground truth and tracker. The equation shown
in Eqn. 8.
=
area
(
R
tracked
R
GT
f
i
∩
)
f
i
O
tracked
i
)
,
(8)
area
(
R
tracked
f
i
∪ R
GT
f
i
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