getTrackVelocities
Obtain updated track velocities and velocity covariance matrix
Syntax
Description
returns velocities of tracked objects.velocity
= getTrackVelocities(tracks
,velocitySelector
)
[
also returns the track velocity covariance matrices.velocity
,velocityCovariances
]
= getTrackVelocities(tracks
,velocitySelector
)
Examples
Find Velocity of 3-D Constant-Acceleration Object
Create an extended Kalman filter tracker for 3-D constant-acceleration motion.
tracker = multiObjectTracker('FilterInitializationFcn',@initcaekf);
Initialize the tracker with one detection.
detection = objectDetection(0,[10;-20;4],'ObjectClassID',3);
tracks = tracker(detection,0);
Add a second detection at a later time and at a different position.
detection = objectDetection(0.1,[10.3;-20.2;4],'ObjectClassID',3);
tracks = tracker(detection,0.2);
Obtain the velocity vector from the track state.
velocitySelector = [0 1 0 0 0 0 0 0 0; 0 0 0 0 1 0 0 0 0; 0 0 0 0 0 0 0 1 0]; velocity = getTrackVelocities(tracks,velocitySelector)
velocity = 1×3
1.0093 -0.6728 0
Velocity and Covariance of 3-D Constant-Acceleration Object
Create an extended Kalman filter tracker for 3-D constant-acceleration motion.
tracker = multiObjectTracker('FilterInitializationFcn',@initcaekf);
Initialize the tracker with one detection.
detection = objectDetection(0,[10;-20;4],'ObjectClassID',3);
tracks = tracker(detection,0);
Add a second detection at a later time and at a different position.
detection = objectDetection(0.1,[10.3;-20.2;4.3],'ObjectClassID',3);
tracks = tracker(detection,0.2);
Obtain the velocity vector from the track state.
velocitySelector = [0 1 0 0 0 0 0 0 0; 0 0 0 0 1 0 0 0 0; 0 0 0 0 0 0 0 1 0]; [velocity,velocityCovariance] = getTrackVelocities(tracks,velocitySelector)
velocity = 1×3
1.0093 -0.6728 1.0093
velocityCovariance = 3×3
70.0685 0 0
0 70.0685 0
0 0 70.0685
Input Arguments
tracks
— Object tracks
array of objectTrack
objects | array of structures
Object tracks, specified as an array of objectTrack
objects or an
array of structures containing sufficient information to obtain the track
velocity information. At a minimum, these structures must contain a
State
column vector field and a positive-definite
StateCovariance
matrix field. For a sample
track structure, see toStruct
.
velocitySelector
— Velocity selection matrix
D-by-N real-valued matrix.
Velocity selector, specified as a D-by-N real-valued matrix of ones and zeros. D is the number of dimensions of the tracker. N is the size of the state vector. Using this matrix, the function extracts track velocities from the state vector. Multiply the state vector by velocity selector matrix returns velocities. The same selector is applied to all object tracks.
Output Arguments
velocity
— Velocities of tracked objects
real-valued 1-by-D vector | real-valued M-by-D matrix
Velocities of tracked objects at last update time, returned as a 1-by-D vector or a real-valued M-by-D matrix. D represents the number of velocity elements. M represents the number of tracks.
velocityCovariances
— Velocity covariance matrices of tracked objects
real-valued D-by-D-matrix | real-valued
D-by-D-by-M
array
Velocity covariance matrices of tracked objects, returned as a real-valued D-by-D-matrix or a real-valued D-by-D-by-M array. D represents the number of velocity elements. M represents the number of tracks. Each D-by-D submatrix is a velocity covariance matrix for a track.
More About
Velocity Selector for 2-Dimensional Motion
Show the velocity selection matrix for two-dimensional motion when the state consists of the position and velocity.
Velocity Selector for 3-Dimensional Motion
Show the velocity selection matrix for three-dimensional motion when the state consists of the position and velocity.
Velocity Selector for 3-Dimensional Motion with Acceleration
Show the velocity selection matrix for three-dimensional motion when the state consists of the position, velocity, and acceleration.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
See Also
Functions
Objects
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