The temporality of spatial data can add another dimension in finding patterns and relationships in your analysis. ArcMap comes with a suite of tools that allows you to “time-enable” your data layers, assuming that it comes with a date attribute.
The following tutorial takes a sample database for crime in Westwood (taken from http://crimemapping.com) over a 2 month period, and plots it on an interactive, temporal view in ArcMap.
Step 1: Loading your data onto ArcMap
- Download the tutorial data, unzip it to a local drive
- Open ArcMap and load the data (crime.shp)
- Symbolize the crime data by categories, choosing “type” as the value field, click on the “add all values” button, and choose a symbol style that looks better than the default “non” circle provided by ESRI.
- Go to the label tab, and label each feature by “type”
- Add a base layer of your choice
Step 2: Time enabling your data
- Open the attribute table for the crime data. Inspect the table, and notice the “date” field
- Open the property window for the crime layer and click on the “time” tab
- Click on the checkbox to “enable time on this layer”
- Click on the “calculate” button. This will calculate the time bounds for this layer.
- Set the “Time step interval” to 1 day, allowing us to inspect the data one day at a time.
- Click OK
Step 3: Visualizing data over time
- Click on the Time Slider button
- Push the play button, and inspect the map. What do you see?
- Click on the options button
- Under the “Time Display” tab, enable “Show time on map display” and choose a date display that you like.
- Under the “Playback” tab, set the speed to a desired setting and check the box next to “Refresh the display…” This will allow you to drag the time slider interactively.
- Click OK and play with the time enabled data. What trends do you see?
Step 4: Adding Directional Distributions
- Open ArcToolbox, and navigate to Spatial Statistics Tools, Measuring Geographic Distributions, and double click on Directional Distribution.
- For Input Feature Type, choose “crime”, for Case Field, choose “date”. Make sure to save the output to a local folder of your choice, and name it “crime_distribution.shp”
- When the new layer is loaded to your map, go to its properties and click on the “Time” tab
- Enable the time on the layer, click on “calculate”, and set the time interval to 1 day
- Go to the Symbology tab, click on the single symbol, fill color to red, and the outline color to “no color”
- Go to the Display tab, and set the Transparency to 80%
- Click OK, and play the time slider again.
Step 5: Post To the Course Website
Post a screenshot (something similar to the picture above) to your Lab 10 blog.