Playback Manager is a tool used to analyze tracking data by playing it back in Tracking Analyst.
In Tracking Analyst, there are two different modes for viewing tracking data: real-time mode and playback mode. By default, Tracking Analyst begins in real-time mode and remains in real-time mode as long as the Playback Manager dialog box is closed. In real-time mode, Tracking Analyst sets the time displayed on the map equal to the time on your system clock. This is useful because it allows data from real-time tracking layers to appear on your map as soon as they are received by the tracking service. While in real-time mode, fixed-time tracking layers will only be displayed on your map if their events exist in the past.
Whenever the Playback Manager dialog box is open, Tracking Analyst is in playback mode. In playback mode, Playback Manager controls the time that is being displayed on the map, rather than your system clock. Playback Manager allows you to play back fixed-time tracking data in the past or in the future as well as real-time tracking data.
Real-time tracking data is temporarily stored in memory as it streams in. If you are viewing a real-time tracking layer, opening the Playback Manager dialog box allows you to replay all the events that were received up to the instant that you opened Playback Manager. Real-time tracking events that are received while Playback Manager is open are held in system memory, and the real-time tracking layer is updated when you close Playback Manager and exit playback mode.
Displaying data using Playback Manager
Playback Manager controls the display of tracking data by controlling the current time that is displayed on your map. By default, only events in the past—before the current time—will be displayed on your map. As the current time increases during playback, more and more events appear on the map. However, if the symbology options provided by Tracking Analyst are used, it can make the playback of tracking data more interesting. For example, time windows can be used to selectively display data as current time changes. Also, special symbology can be defined for the most current events in your tracking data. This allows you to see each tracked object in your data moving around your map as time passes. Once you become familiar with Playback Manager and the symbology options provided by Tracking Analyst, you will discover that the possibilities are endless.
The playback rate
The playback rate determines the speed at which tracking data will be played back by Playback Manager. It also determines the step size if you step forward or backward through your data. You must understand the characteristics of your data to choose an appropriate playback rate. For example, a playback rate of one day per second will not work if the temporal extent of your tracking layer is only one hour. Usually, an appropriate playback rate can be found through trial and error.
The playback rate is set using the Set the playback rate text box and drop-down list. It can be further adjusted by clicking and dragging the speed indicator in the center of Playback Manager toward the Slower or Faster label.
The playback window
The playback window is defined by the start and end times specified in the Playback Manager dialog box. Playing back data can only occur within the playback window. The playback window can be changed manually by clicking in the Start and End drop-down lists and changing the dates and times displayed. The Set playback window to temporal extent of drop-down list can also be used to set the playback window to the temporal extent of a layer in your map document. The temporal extent of a layer is the time between the earliest and latest events in the data.
The first time Playback Manager is opened, the playback window defaults to the temporal extent of all tracking layers in your map. Changes made to the playback window are saved by Playback Manager. If you add new tracking layers to your map after using Playback Manager, the playback window will not be updated automatically to include the new data. By setting the temporal extent to all temporal layers, you can be sure that the new layer is included in the playback window.
Changing the start, current, and end times
There are several ways to change the current time. If you push the Play button, the current time changes automatically as Playback Manager steps through the time until it reaches the end of the playback window. If you are not playing back data, the buttons to the right of the histogram can be used to move the current time forward or backward by set increments. To jump to a specific time, you can click the data histogram or enter a new value directly into the Current text box. Playback Manager always shows the current date and time in the text box. It can be modified by clicking any of the settings in the text box (month, day, year, hour, minute, or second) and entering a new value. You can also use the UP and DOWN ARROW keys to change these values. Clicking the drop-down arrow reveals a calendar object that can be used to set the date. You can change the start and end times displayed in the Start and End text boxes in the same way.
By default, the current time set in Playback Manager is a single time used to display data cumulatively. If you uncheck the Cumulative check box, you can display data by setting a time window instead.
The data histogram
The data histogram in the panel at the top of the Playback Manager dialog box indicates how much data exists at different times in the playback window you have specified. The histogram only shows data that is within the current playback window. The red time indicator in the histogram represents the current time. When you aren't playing back data, you can click any point on the histogram to set the current time equal to where you click. You will notice that the red time indicator moves to the point in time where you clicked. You can also click and drag the red time indicator back and forth across the histogram to change the current time. The map display refreshes constantly, allowing you to manually play back the data forward or in reverse.