objectTrack
Description
objectTrack
captures the track information of a single object.
objectTrack
is the standard output format for trackers.
Creation
Description
creates an
track
= objectTrackobjectTrack
object with default property values. An
objectTrack
object contains information like the age and state of a
single track.
Tip
To create an empty objectTrack
object, use
objectTrack.empty()
.
allows you to set properties using one or more name-value pairs. Enclose each property
name in single quotes.track
= objectTrack(Name,Value
)
Properties
TrackID
— Unique track identifier
1
(default) | nonnegative integer
Unique track identifier, specified as a nonnegative integer. This property distinguishes different tracks.
Example:
2
BranchID
— Unique track branch identifier
0
(default) | nonnegative integer
Unique track branch identifier, specified as a nonnegative integer. In
multi-hypothesis tracking, a track may have multiple hypotheses, each represented by a
different branch. This property distinguishes different track branches. For more
information, see trackerTOMHT
(Sensor Fusion and Tracking Toolbox).
Example:
1
SourceIndex
— Index of source track reporting system
1
(default) | nonnegative integer
Index of source track reporting system, specified as a nonnegative integer. This property identifies the source that reports the track.
Example:
3
UpdateTime
— Update time of track
0
(default) | nonnegative real scalar
Time at which the track was updated by a tracker, specified as a nonnegative real scalar.
Example: 1.2
Data Types: single
| double
Age
— Number of times track was updated
1
(default) | positive integer
Number of times the track was updated, specified as a positive integer. When a track
is initialized, its Age
is equal to 1
. Any
subsequent update with a hit or miss increases the track Age
by 1.
Example:
2
State
— Current state of track
zeros(6,1)
(default) | real-valued N-element vector
The current state of the track at the UpdateTime
, specified as
a real-valued N-element vector, where N is the
dimension of the state. The format of track state depends on the model used to track the
object. For example, for 3-D constant velocity model used with constvel
, the state vector is [x;
vx;
y; vy;
z;
vz].
Example:
[1 0.2 3 0.2]
Data Types: single
| double
StateCovariance
— Current state uncertainty covariance of track
eye(6,6)
(default) | real positive semidefinite symmetric N-by-N
matrix
The current state uncertainty covariance of the track, specified as a real positive
semidefinite symmetric N-by-N matrix, where
N is the dimension of state specified in the
State
property.
Data Types: single
| double
StateParameters
— Parameters of the track state reference frame
struct()
(default) | structure | structure array
Parameters of the track state reference frame, specified as a structure or a structure array. Use this property to define the track state reference frame and how to transform the track from the source coordinate system to the fuser coordinate system.
ObjectClassID
— Object class identifier
0
(default) | nonnegative integer
Object class identifier, specified as a nonnegative integer. This property distinguishes between different user-defined object types. For example, you can use 1 for objects of type "car", and 2 for objects of type "pedestrian". 0 is reserved for unknown classification.
If you specify this property as a nonzero integer, you can use the
ObjectClassProbablities
property to specify the classification
probabilities.
Example:
3
ObjectClassProbablities
— Object classification probabilities
1
(default) | N-element vector of nonnegative scalars
Object classification probabilities of the track, specified as an
N-element vector of nonnegative scalars. N is
the total number of possible classes of the track. Each element must be a scalar in the
range [0 1]
, and the sum of all elements must be equal to 1.The
i-th element of the vector corresponds to the probability that the
track belongs to the class i.
Example:
[0.7 0.3]
TrackLogic
— Track confirmation and deletion logic type
'History'
(default) | 'Integrated'
| 'Score'
Confirmation and deletion logic type, specified as:
'History'
– Track confirmation and deletion is based on the number of times the track has been assigned to a detection in the latest tracker updates.'Score'
– Track confirmation and deletion is based on a log-likelihood track score. A high score means that the track is more likely to be valid. A low score means that the track is more likely to be a false alarm.'Integrated'
– Track confirmation and deletion is based on the integrated probability of track existence.
TrackLogicState
— State of track logic
1-by-M logical vector | 1-by-2 real-valued vector | nonnegative scalar
The current state of the track logic type. Based on the logic type specified in the
TrackLogic
property, the logic state is specified as:
'History'
– A 1-by-M logical vector, where M is the number of latest track logical states recorded.true
(1) values indicate hits, andfalse
(0) values indicate misses. For example,[1 0 1 1 1]
represents four hits and one miss in the last five updates. The default value for logic state is 1.'Score'
– A 1-by-2 real-valued vector, [cs, ms]. cs is the current score, and ms is the maximum score. The default value is[0, 0]
.'Integrated'
– A nonnegative scalar. The scalar represents the integrated probability of existence of the track. The default value is 0.5.
IsConfirmed
— Indicate if track is confirmed
true
(default) | false
Indicate if the track is confirmed, specified as true
or
false
.
Data Types: logical
IsCoasted
— Indicate if track is coasted
false
(default) | true
Indicate if the track is coasted, specified as true
or
false
. A track is coasted if its latest update is based on
prediction instead of correction using detections.
Data Types: logical
IsSelfReported
— Indicate if track is self reported
true
(default) | false
Indicate if the track is self reported, specified as true
or
false
. A track is self reported if it is reported from internal
sources (senors, trackers, or fusers). To limit the propagation of rumors in a tracking
system, use the value false
if the track was updated by an external
source.
Example: false
Data Types: logical
ObjectAttributes
— Object attributes
struct()
(default) | structure
Object attributes passed by the tracker, specified as a structure.
Object Functions
toStruct | Convert objectTrack object to
struct |
Examples
Create Track Report using objectTrack
Create a report of a track using objectTrack
.
x = (1:6)'; P = diag(1:6); track = objectTrack('State',x,'StateCovariance',P); disp(track)
objectTrack with properties: TrackID: 1 BranchID: 0 SourceIndex: 1 UpdateTime: 0 Age: 1 State: [6x1 double] StateCovariance: [6x6 double] StateParameters: [1x1 struct] ObjectClassID: 0 ObjectClassProbabilities: 1 TrackLogic: 'History' TrackLogicState: 1 IsConfirmed: 1 IsCoasted: 0 IsSelfReported: 1 ObjectAttributes: [1x1 struct]
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
The
TrackLogic
property can only be set during construction.
Version History
Introduced in R2020aR2022b: Represent track class probability
The objectTrack
object has a new property,
ObjectClassProbabilities
, which represents the probabilities that the
tracked target belongs to specific classes.
See Also
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