Pilot project report - Campus Crime Mapping

January 8, 2008

Dr. Eric Compas
Eric Helwig
Brian Stueck
Jesse Stroms
UWW Geography/Geology Department

Summary

The purpose of this pilot project was to establish a procedure for mapping crime incidents on the UW-Whitewater campus utilizing existing police department data. The project was successful in integrating a set of points digitized using Google Earth with the police department incident reporting system to generate a GIS data set that can be used for a variety of mapping and query purposes. The project also established that the imagery used within Google Earth for the UWW campus is accurate to within 3m — accuracy sufficient for crime mapping. The campus's CAD files of building outlines, however, was not sufficient for mapping incidents and would require further refinement to be useful for this purpose.

Overview of procedure

1. Establish an accurate base for locating crime incidents

• tests using differentially-corrected GPS locations across campus confirmed that Google Earth's imagery was of sufficient accuracy (approx. 3m) for crime mapping purposes

• campus CAD files of building footprints, parking lots, and walkways could not easily be georeferenced to this level of accuracy

2. Digitize existing crime incident locations in Google Earth

• done for a sample of 2007 incidents by Deanne Thornsen within police department

• exported KML file and converted to Shapefile via GPS Utility (Shareware)

• Shapefile converted to Personal Geodatabase (a Microsoft Access file) via ArcCatalog

3. Export crime incidents from department recording software and import into Microsoft Access

• exported CSV (comma-separated value) text file provided by Deanne Thornsen

• imported in to the Personal Geodatabase file

4. Relate/join digitized points from Step 3 with incident date from Step 4

• temporary relate/join created within ArcMap

Products

With an integrated GIS data set for crime incidents, a variety of different products can be generated. Figure 1 shows an example map generated from the data set within ArcGIS. Given the fields within the GIS data file, additional “views” or “queries” of the data could be conducted to show only those incidents within a particular period of time or those of a particular type. Additionally, the data can be exported back to Google Earth (see Figure 2) (click here to view file within Google Earth).

Fig. 1. Crime incidents shown within ArcMap (click for full image).

Fig. 2. Crime incidents shown within Google Earth (click to view file in Google Earth).

Issues and resolutions

Several issues arose in this pilot which would need to be overcome before crime incident mapping could become a standard component of the police department's business practices. Issues encountered include:

1. Digitizing a crime location is a completely separate process from the police reporting system. Thus, the data is stored separately which increases the chances of errors or mismatches. Optimally, the location of the incident would be recorded within the police reporting system in latitude and longitude fields.

2. The ability to convert between Google Earth and ArcGIS formats was cumbersome and would be difficult to automate. Programming may be required to facilitate automated conversions.

3. While the import of incident data into Access from the police department's reporting software was successful, several refinements to the process and the police reporting system would be required to have full querying capabilities. For example, the time of the incident was imported as a text field and not as a time field. Selecting all evening crimes, therefore, wouldn't be possible. Better outlining the mapping products needed would help target where to refine this process.

Additional possibilities

In future work, several improvements could be made to the way crime information is viewed within Google Earth. Figure 3 shows a single point with a balloon providing additional information about the incident and a link to the incident's full record.

Fig. 3. Crime incident with description shown within Google Earth (click to view file in Google Earth).

Finally, the crime data could be made fully three-dimensional and displayed on a three-dimensional view of campus (see Figure 4 for an example).

Fig. 3. Crime incident with description shown within Google Earth (click to view file in Google Earth).