Exploring Patterns of Crime In Los Angeles County Using A Density Surface Model

Table of Contents

  1. Exploring Patterns of Crime In Los Angeles County Using A Density Surface Model
  2. Setting up Your Workspace
  3. Preparing the Data
  4. Skill Drill: Clipping the LA City Boundaries to the Census LA County Boundary
  5. Skill Drill: Adding XY Data
  6. Skill Drill: Clipping the Crime Data to the Census LA County Boundary
  7. Skill Drill: Creating a Subset of the Data Based on Crime Category
  8. Changing Global Environment Settings for Raster Processing
  9. Creating a Density Surface Model Using the Simple Method
  10. Creating a Density Surface Model Using the Kernel Method
  11. Skill Drill: Creating A Density Surface Model Based on Your Criteria

Setting up Your Workspace

By now you should be familiar with file management protocols for GIS. In a workplace setting, having consistent file management rules is necessary to prevent errors and lost data. In this course, we will be using a particular folder structure. For each lab activity, you will start by creating your workspace folder on the local hard drive. If you are a registered student at Humboldt State University working in a computer lab, you will use the desktop as your local hard drive location. You may also use an external USB drive if you plan to work in multiple places.

Avoid using networked drives such as Google Drive. Networked drives can increase processing time and cause technical glitches.

The top-level folder should indicate the lab assignment. Within this folder, create the following three subfolders: original, working, and final. Your original folder will contain original unaltered data. Your working folder will contain data you create or alter through GIS analysis operations. The final folder contains any output, such as JPG, PDF maps, QAQC forms, or lab reports in the form of Microsoft Word documents. This organization represents the core folder structure you should maintain. You can create more detailed organizational structures within these folders if you wish.

An image of a basic folder structure used in this course.
A basic workspace folder structure.

Disable Background Geoprocessing

In the ArcGIS software, the Background Geoprocessing setting is often turned on by default. This setting allows users to continue to work while a tool is running in the background. However, sometimes this setting will stop tools from running or cause other unforeseen problems. To reduce that chances of the ArcGIS software crashing during this exercise, I recommend turning this setting off. After launching ArcMap, open the Geoprocessing options from the Geoprocessing menu. Under Background Geoprocessing, uncheck the box next to the word Enable.

 Spatial Analyst Extension

The steps in this activity involve using the Spatial Analyst extension. After launching ArcMap, make sure this extension is activated.