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

Preparing the Data

The following Skill Drills for preparing the data use the knowledge you have learned in previous courses, including Geospatial Concepts (GSP 101) and Geographic Information Science (GSP 270). Therefore, the instructions do not contain many step-by-step details. You should refer to previous coursework if needed. Registered students may also post questions on the weekly Q&A Discussion Forum on the Canvas LMS.

Skill Drill: Acquire data from the Los Angeles GIS Data Portal

An image of the Los Angeles Data Portal.

The Los Angeles County GIS Data Portal, maintained by the County of Los Angeles, is a website where you can download many different types of GIS datasets. The website includes instructional material on how to use the site, including text and videos. You should already be somewhat familiar with this website based on previous coursework. If you need a refresher, I recommend watching the instructional videos before you begin. Navigate to the Los Angeles County GIS Data Portal and use the keyword city boundaries to search for city polygons on the website. Locate a shapefile containing the city polygons and download the file. Decompress the file in your original folder and check the spatial reference system.

If necessary, use the Project tool to create a copy of the data with the NAD 83 UTM Zone 11 spatial reference system.

An image of the project tool
The Project tool never alters the original data. It creates a copy of the data with a new spatial reference system.

In ArcMap, open a new blank map document add the layer with the correct spatial reference to your Table of Contents. This layer will define the spatial reference for the dataframe window if it is the first layer loaded into the table of contents.

An image of the LA cities added to the map
In ArcMap, the dataframe window adopts the spatial reference from the first layer loaded into the Table of Contents.