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

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.
An image of the Los Angeles County GIS Data Portal

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.