Lab 01: Create an Area of Interest with GeoJSON.io (DRAFT)

Turn-in for grading: This lab includes material that must be turned in for grading. Export your AOI file using the naming convention below and submit it to Canvas.

Introduction

Almost every spatial analysis project starts with defining a study area — an Area of Interest (AOI). An AOI sets the geographic scope of your work: it tells your tools where to load data, where to clip rasters, and where to run calculations.

In this lab you will use geojson.io, a lightweight browser-based tool for creating and editing vector features without any software installation. You will draw a rectangular AOI that is at least as large as the Stanford campus, then relocate it to a place that is personally meaningful to you — a research site, hometown, field area, or any other location you want to study this quarter.

The result is a single GeoJSON file that you will use again in later labs as your personal study area.

Why GeoJSON?

GeoJSON is a plain-text, open standard for encoding geographic features using JSON.

• A single self-contained file (no sidecar files, unlike shapefiles).
• Human-readable — you can open it in any text editor and read the coordinates.
• Natively understood by QGIS, Google Earth Engine, Leaflet, Mapbox, GitHub, and most other modern GIS tools.
• Coordinates are always in WGS 84 (EPSG:4326) — the same geographic CRS you encountered in the projection error lab.

Part 1: Get Oriented with geojson.io

1. Open https://geojson.io in your browser. No login or installation is required.
2. You will see two main areas:
   • Right panel — a list of your features and panels for editing properties and raw JSON.
   • Left panel — an interactive map you can pan and zoom.

1. Take a moment to locate the drawing toolbar on the right side of the map. The tools, from top to bottom, are:
   • Draw point ()
   • Draw line ()
   • Draw polygon ()
   • Draw rectangle () ← this is the one you will use
2. At the top of the page, notice the Save button — you will use this at the end to save your work.

Part 2: Draw a Rectangle Around the Stanford Campus

You will use the Stanford campus as a size reference. Your final AOI must be at least this large.

Step 1: Navigate to the Stanford Campus

1. In the map search bar (top-left of the map, ⌘+K to open), type Stanford University, Palo Alto, CA and press Enter, or simply pan and zoom to the campus manually

   

2. Zoom to a level where you can see the full campus footprint including the Dish, the main quad, and the athletic facilities. A zoom level of 13–14 works well.

Step 2: Draw a Rectangle

1. Click the Draw Rectangle tool in the toolbar.
2. Click and then move across the map to draw a rectangle that covers the entire Stanford campus — from the Dish area in the southwest to the east edge of campus near El Camino Real.
3. Click again to finish the rectangle.
4. The rectangle's will appear in the </>JSON Panel panel and as a polygon on the map.

Tip: If the rectangle is not quite right, click on the Edit Geometries tool , then drag individual vertices to reshape it. Click Save to save your changes

Step 3: Check the Size

After drawing, look at the raw GeoJSON in the JSON panel on the left. You will see a FeatureCollection containing one Feature with a Polygon geometry. The four coordinate pairs define the corners of your rectangle in [longitude, latitude] order.

This is the minimum size your final AOI must be. A rectangle covering the full Stanford campus is roughly 3–4 km east-west by 5–6 km north-south.

Part 3: Now Create a Rectangle at Your Place of Significance

Now you will relocate the rectangle you just drew to a place that is meaningful to you. This might be:

• Your hometown, neighborhood, or campus back home.
• A research area or field site from another course or project.
• A place in the world you are studying or find interesting.

The requirement is that the relocated rectangle is at least as large as the Stanford campus box you just drew. You may make it larger.

Delete and Redraw

1. Right-click the rectangle in the feature list or on the map and choose Delete.
2. Navigate to your chosen location using the search bar.
3. Activate the rectangle tool and draw a new rectangle of at least the same size.

Part 4: Add a Property to Your Feature

Adding descriptive properties to your features is good practice — it makes the file self-documenting and easier to use in downstream analysis.

1. Select your rectangle (click it on the map or in the feature list).
2. The Feature Editor popup will appear.
3. Type the propery: name into the first cell, and the value: your location label into the second cell.
4. Click Add row and create property/vlue pairs for the following:

1. Click Save to Save the Properties of the feature.

2. Note how the properties look in the </>JSON Panel.

   

3. Click on the Table Tab for a more familiar spreadsheet view.

   

Part 5: Export Your AOI as GeoJSON

1. Click Save at the top of the page.
2. Choose GeoJSON as the format.
3. Save the file. Your browser will likely save it as map.geojson — rename it immediately using the naming convention below.

File Naming Convention

sunetid_week01_lab01_aoi.geojson

Replace sunetid with your actual Stanford SUNet ID. For example:

jsmith_week01_lab01_aoi.geojson

Deliverable

Submit your exported GeoJSON file to the Week 01 Lab 01 assignment on Canvas.

Checklist before submitting:

• [ ] The file is in GeoJSON format.
• [ ] The rectangle covers an area at least as large as the Stanford campus.
• [ ] The feature has name, sunetid, and description properties filled in.
• [ ] The filename follows the convention sunetid_week01_lab01_aoi.geojson.

Reference: geojson.io Interface Summary