Working with video layers and time
Like many other GIS data sources, video layers often have a temporal component. That is, the video has a position and extent in time. You can define time properties for video layers in ArcGlobe on the Time tab of the Layer Properties dialog box, including information such as the start time, duration, and time zone of the video. This allows the definition of time for very diverse video sources, for example, real-time security camera video, a time-lapse weather pattern video that spans an entire day, or even a simulated geological video that spans thousands of years.
When to define time for video layers
Video layers do not need to have time information defined for them to display them inside ArcGlobe. They can always be played individually by right-clicking the layer in the table of contents and clicking Play. This way of displaying video layers will ensure that all video frames are displayed and is the most intuitive way of seeing videos draped on the surface of the globe.
If, however, you need to view specific moments in time, with your video layer synchronized with other videos and time-enabled data, then you must define the temporal properties of your video layer. This way of displaying video layers will not ensure that all video frames are displayed, as the interactive Time Slider window only displays a set of predefined moments in time, or ticks, which all time-enabled layers must share. The influence of multiple data sources can easily result in time slices that are significantly coarser than what the video layer contains. The advantage is that you will be able to move the slider to a specific time and see all your time-aware data sources in sync.
The image here depicts the temporal extents and time step intervals for three layers in an ArcGlobe document. Each labelled section is further defined in the following table.
Labelled feature | Description |
|---|---|
Video layer | This is an example of 30 minutes of security footage, at 10 frames per second, starting at 1:07 A.M. on 1/1/2001. |
Weather layer | This is an example of five hours of precipitation imagery, at one-hour snapshots, starting at 12:00 A.M. on 1/1/2001. |
Traffic layer | This is an example of three hours of traffic congestion line data, at five-minute intervals, starting at 12:40 A.M. on 1/1/2001. |
Location of all layers synchronized | When the time slider is moved to the location marked by the vertical dashed line, you will see all three layers synchronized to 1:20 A.M. on 1/1/2001. |
Time properties for video layers
For a video layer to honor time, you will use the Time tab of the Layer Properties dialog box and check the Enable time on this layer option. This will allow you to view a specific moment in time within the video layer by adjusting the slider on the Time Slider window. It will also allow you to view other time-enabled data synchronized with your video layer.
Below is an image labelling the different time properties for video layers. Each property is further defined in the table following the image.
Property | Description |
|---|---|
Start Time | The start date and time defines the moment in time captured in the first frame of the video. |
Time Step Interval | This defines the granularity of the temporal data and can be thought of as how often the time values were recorded for your data. For video layers, this value represents the length of time each frame represents; the duration can be very small, such as 100 milliseconds (for example, a security camera video recorded at 10 frames per second). |
Live feed (no end time) | The live feed option is an indicator whether the video has an end time, for example, whether or not the source is a continuous stream of images, such as from a live webcam. The video layer will keep requesting frames from the source beyond the initial day and time when the layer was added into ArcGlobe, when this option is checked. |
Time Zone | This specifies the time zone in which your data was recorded. This is important if you want to visualize datasets from different time zones. |
Daylight savings | This indicates that the source data was collected with time values that incorporate daylight savings time. |
Viewing a moment in time for a video layer
Once your video has time properties enabled and configured, you can view a specific time slice within that video using the Time Slider window. Add the window to the display by clicking the Time 
control on the Tools toolbar. Then simply move the slider to the desired time increment, and the video layer will draw the frame for that moment in time. If the specified time is outside the range of the video, it will show a placeholder frame to indicate that the video does not have content for that moment.
Playing video layers through the time slider
A video that has time properties can also be viewed by using the Play button on the Time Slider window. However, you should be aware that the time slider will define the frame rate in real-time units, and this will override any properties defined in the video layer. For example, if you have a security camera video that plays at 20 frames per second, but the time slider defines a time interval of one second, you will only see every 20th frame when playing that video layer through the time slider.
Tip:- To play a video layer at its full resolution using the Time Slider window, make the video layer the only time-enabled layer in ArcGlobe and define the layer's Time Step Interval property as Milliseconds to match the video's frame rate. For example, a 20-frames-per-second video layer would use a time step interval of 50 milliseconds.
- Be cautious when applying very small time step intervals on multiple layers. For example, defining a 50-millisecond time step interval when one of your time-enabled layers represents a few years of monthly rainfall values would create billions of time slices on the time slider.