2. Configure the DWELL configuration options for target detection.
Warning Symbol
Enter the name of an icon to display. If no icon exists by this name, then the text
that is entered shall be displayed at each centroid location. The icon
automatically rotates to point in the direction of target motion.
In the example above, Plane is an icon of an airplane that is flying North. Bird
icons are also provided.
Correlation Threshold
This is the threshold for the number of points in the "pile" product X4. For
example, the number 8 represent 2 points. Note that the smoothing in the pile
product typically reduces the number of points from the maximum value. Thus a
pile product value of 2 would correspond to a greater number at very sharp
maximum.
The correlation threshold is the primary tunable parameter to optimize the
probability of detection and false alarm rate.
The appropriate value of the correlation threshold depends on the length of
the DWELL sequence. Longer DWELL times (more input products) produce
larger "piles".
Add Wind, Use VVP, Speed, and Heading Range
The track of the targets is used during the "pile" process to add up targets that
are moving at the expected velocity. The velocity of the targets is the result of the
target's flight (air velocity) and the wind. These fields are used to account for
these eects.
Add Wind specifies whether you want the wind eect to be added to the target
flight velocity vector. If this is enabled, the Speed Range is the expected range of
speed of the targets in still air, that is, their flight speed.
If you select Add Wind, select Use VVP to control where the algorithm gets the
wind. The UNFOLD VVP product is used for mean wind information.
Otherwise the Setup product section has a default wind speed and direction. In
tropical maritime trade wind regions this could be set fairly reliably to a single
value of speed and direction. For most regions, the default wind is not usually a
very good value. You can change this value in real time using the setup_change
utility.
If you choose not to use the Add Wind feature, then the range of speeds
must include the expected variation in the wind speed as well as the target
speed. The greater range of speeds results in more false alarms and requires
more trial winds (slower algorithm performance).
Target Size
IRIS Product and Display User Guide M211319EN-H
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