Temporal data represents a state in time, such as the land-use patterns of Hong Kong in 1990 or rainfall in Honolulu on July 1, 2009. This data comes from many sources, ranging from manual data entry to data collected using observational sensors or generated from simulation models. The following are applications of temporal data in GIS:
- Visualize the locations of ocean mammals to understand patterns in their movement.
- Understand population increases per city.
- Indicate how fatalities from a disease are increasing based on changing colors in the layer symbology.
- View ocean temperature changes or weather patterns over time.
Store time values
Time values in data can represent a moment in time, sampled at a regular or irregular interval. These time values are stored in a single attribute field and can be used to visualize temporal data at a particular time. For example, stream flow data might be collected at a regular interval every 15 minutes. However, lightning or earthquake data is collected irregularly—meaning, whenever the lightning storm or earthquake occurs.
Time values can also represent durations of time, such as when an event occurs over a period of time. Time values in this case are stored in two fields, one representing the start time of the event, and the other representing the end time of the event. For example, polygon features representing a fire perimeter have a start and end time that depend on when the fire started and ended.
Any layer that does not have stored time field values can be made time aware manually by providing a fixed time extent layer property. This will show the entire layer within that time extent when stepping or playing through the time slider. An example is an aerial image that was taken on a particular date and considered current for three months.
Use temporal data
Maps that contain temporal data provide additional functionality and controls to explore the data over time. Individual layers are configured to indicate which attribute fields define the data's time extent, then the data can be explored and filtered through time with the time slider. The time slider provides controls to explore temporal data and is available at the top of any map view that contains temporal layers or stand-alone tables. Table views opened for a time-aware layer will, by default, filter the displayed rows based on the map's current time extent. This option can be disabled using the filter controls at the bottom of the table view.
You can filter the list of layers in the Contents pane of a map or scene to only time-configured layers.
Time properties are stored when you create a bookmark, which captures the location in both space and time.
Animation can also be used in conjunction with time-aware layers in your map. You can use animation to show content changes through time and export it to a video to share.