One of the new features of ArcGIS 10 is the ability to “time-enable” your data in ArcMap. Visualizing how data changes over time provides opportunities for powerful, more in-depth analysis. Using ArcGIS 9.3, you can visualize temporal change by creating an animation. You can still create animations at version 10, but there’s an easy alternative as well.
The example below shows how to use the new tools to visualize piracy-related incidents that occurred between March, 2007 and February, 2009 in and around the Gulf of Aden.
The map document shown on the right includes the World Topographic Map basemap from ArcGIS Online for geographic context, and an Incidents point layer that represents locations where pirate attacks occurred. The Incidents data is a set of Anti-Shipping Activity Messages that was downloaded as a shapefile from the National Geospatial-Intelligence Agency (NGA) Maritime Safety Information portal and loaded into a file geodatabase feature class.
The points on the map reveal the number of attacks that occurred during the time period, and you can see the incident distribution. By time-enabling the incidents, however, you can visualize the progression of the attacks and find out whether there were “clusters within the cluster.”
The Incidents layer contains a DateOfOcc attribute, which stores the date (mmddyyyy) that each attack occurred. In order to time-enable a layer, you must have one (or more) fields that stores time data (such as dates). A best practice is to store time data in a date field, but numeric or text fields will also work.
Set Time Properties
At ArcGIS 10, the ArcMap Layer Properties dialog box has a Time tab. So the first step to visualizing the time component of a layer is to simply open the dialog box and click the Time tab. Then follow the steps below:
- Check the box in the upper-left to “Enable time on this layer.”
- In the Layer Time drop-down list, choose ”Each feature has a single time field.”
- For this example, this is the appropriate setting because the attribute table has only one time field. Sometimes, there are two fields that store time data; for example, StartDate and EndDate.
- For this example, this is the appropriate setting because the attribute table has only one time field. Sometimes, there are two fields that store time data; for example, StartDate and EndDate.
- For Time Field, choose the field in the layer that contains your time data. In this case, it’s DateOfOcc.
- For Time Step Interval, you can manually set the interval or you can let the software calculate an interval based on your data. In this example, 2 days was specified.
- At the bottom of the dialog box, check the box to “Display data cumulatively.”
These settings will draw incidents for each two-day increment and keep earlier incidents displayed as succeeding incidents draw—allowing you to see the pattern of occurrence over the two years spanned by the data.
Time-Enable the Map
- Click OK to apply the layer’s time properties, then click the button on the Tools toolbar to open the Time Slider window. The Time Slider window is new at version 10.
Click the “Enable time on map” button in the upper-left corner of the Time Slider window.
- After clicking this button, only the data associated with the start time displays on the map.
- Click the Play button to see the incidents display in order based on their date of occurrence.
This time visualization reveals that in 2007 there were fewer incidents of piracy, they were much more spread out, and they did not appear to be consistently in close proximity to land. By early 2009, there were significantly more incidents, and they appear to be far more concentrated in the Gulf of Aden, specifically on the Yemen side of the gulf.
The change in incident distribution could be due to an attempt by ships to avoid the Somali Coast. NGA Special Warning Number 123 advises mariners to remain at least 200 nautical miles distant from the Somali Coast.
Sharing Time Visualizations
The time properties are saved with the map document. You can share the time visualization by sharing the map document. But what if the people you want to share with don’t have ArcMap?
From the Time Slider window, you can quickly export a time-enabled map to an .AVI file, which can be viewed using the free Windows Media Player.
Knowing where things occur is the cornerstone of GIS analysis. You have to know where before you can hypothesize why. Another dimension to GIS analysis is when. Knowing where and when things occur means you can not only visualize patterns, but how patterns have evolved over time. With this information, you gain a deeper understanding of your data and can better model and predict future patterns.
Esri Educational Specialist Ryan Otto contributed to this post.
Great post, above, SuzanneB, is there a way to stop the video, at the full coverage? the example-video above stops at where all points are gone………thanks a lot,Nan Hongnnhong@monsanto.com
Yes, you can modify the time slider properties. See this help topic to learn how. http://help.arcgis.com/en/arcgisdesktop/10.0/help/#/About_modifying_time_slider_properties/005z00000019000000/
Many thanks, SuzanneB, I tried the time slider properties before, but I am still not able to get what I want.I have 1000 locations planted from Jan. 1 to Dec. 31, I want the moive ending with all of those 1000 locations in the map. My current movie ending is similar to your example-video above. would you please tell me the detailed steps to follow?thanks a lot,Nannnhong@monsanto.com
I think you may be referring to a video player issue. When viewing the exported video file (.AVI) with Windows Media Player, I’ve found the video automatically closes at the end. In QuickTime, the video stops with the last frame still showing (i.e., all features showing at the end of the time extent). Try QuickTime if you haven’t already.
Hello Suzanne,In my dataset, I have start and stop times for each feature. I’m unclear about Start-Time-Field and End-Time-Field on the Layer Properties > Time Tab. How does that relate to the Time Slider window tab “Time Extent”? What I would like to do is show features as they come online and go offline, year by year. I have different stores that open and close at different years. For each year, I would like all features that are open to cumulatively show on the map. I cannot figure out the right combination of options. thank you for your help. if you would rather take this offline, my email is nsavar@uic.edu–nina.
Hi Nina,It sounds like you need to set the time step interval in the Layer Properties dialog to one year, assuming you’re only interested in viewing stores by year. The time step interval controls how many features display on the map in each sequence of the animation–you could step through by week or month if you wanted to compare activity level within each year (to see which month had the most store openings, for example). In the Time Slider window, you set a time extent to play just a subset of your data in the animation (stores open in a specific year or group of years).