Working with time-based KML data

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With increasing frequency, spatial data collection of various phenomena has grown to include a temporal component; put more simply: data capture may include the means to begin to answer the question of what happened when and where did it happen or what may happen in the future and where will it occur. By animating time-based data you can visualize it at each step and see patterns or trends emerging over time. Examples of phenomena whose data are well-suited for this purpose include:

• Hurricanes, tornados, and other violent meteorological events
• Human or animal migration
• Land use change
• Wildfire or flood progression
• Climate change

One source of this data is KML or KMZ files; so, when you display the Contents of a KML file that you've added to the map that includes time-based data, a time-based animation window appears:

To display the Animate window when it's not visible

If the Animate window is not visible, right click the parent node of an item in the KML Contents window that contains time-based data or right-click the node itself to display its context menu; then on the context menu click Animate...

To play an animation of the KML file's time-based data

To play an animation of the KML file's time-based data, click the Play button (the arrow button in the upper left corner of the Animation window).

To pause or stop the animation at any time

Click the Pause button (dual bars) to pause or stop the animation.

To adjust the time span of the data

1. Uncheck the Lock time span check box. Doing this will allow you to narrow or widen the default time span.





2. Drag the thumbs of the time span sliders. The upper slider moves back in time, the lower slider moves forward in time.
3. Check the Lock time span check box.

To move the time span backwards and forwards manually

• Grab and move the upper slider bar's thumb to move the time span backwards.
• Similarly, use the lower slider bar's thumb to move the span forwards through the total time range of the file.
• If the Lock time span check box is checked you can use either slider to move the time span.

To control what happens after the animation plays once

At the upper right of the dialog you'll see a list of choices.

Select one of the three options to determine what happens after the animation plays once:

To keep the earliest displayed date visible throughout the animation

1. Uncheck the Lock time span check box.
2. Click the Play button.

To set the speed at which the animation plays

Move the Speed control's thumb to the right to increase the speed at which the animation plays.