Lab 5 - Challenge: Refreshers

Objective: Practice creating natural color and false color composites independently.

Introduction

This challenge lab gives you the opportunity to practice the skills you've learned in the previous labs. You'll work with a specific Landsat image to create both natural color and near-infrared false color composites, then analyze what each reveals about an environmental event.

Challenge Task

Create a new script to make two composites - natural color and near-infrared false color for this image:

Image ID:

'LANDSAT/LT05/C02/T1_L2/LT05_022039_20050907'

In your script, make comments with the following information:

  • Where is this image?
  • What environmental event do you think the images show?
  • Compare and contrast the natural and false-color composites.
  • What do the false-color composite help you see that is more difficult to decipher in the natural color composite?

Hints

Remember:

  • Landsat 5 uses Collection 2 Level 2 data
  • Natural color composite: Use bands SR_B3 (Red), SR_B2 (Green), SR_B1 (Blue)
  • False color (NIR) composite: Use bands SR_B4 (NIR), SR_B3 (Red), SR_B2 (Green)
  • You may need to adjust min/max values for optimal visualization
  • Use Map.centerObject() to center on the image
  • Scale factors for Landsat Collection 2 Level 2: multiply by 0.0000275 and add -0.2

Sample Code Structure

// Load the image
var image = ee.Image('LANDSAT/LT05/C02/T1_L2/LT05_022039_20050907');

// Apply scaling factors
function applyScaleFactors(image) {
  var opticalBands = image.select('SR_B.').multiply(0.0000275).add(-0.2);
  return image.addBands(opticalBands, null, true);
}

var scaledImage = applyScaleFactors(image);

// Center the map
Map.centerObject(image, 8);

// Create natural color composite
// YOUR CODE HERE

// Create false color composite
// YOUR CODE HERE

Analysis Questions

After creating your composites, explore the image and answer these questions in your script comments:

  1. Location: Where is this image located? (Hint: Look at the path/row and use geographic features)
  2. Environmental Event: What type of environmental event or phenomenon do you observe? Look for clues in both the natural and false color composites.
  3. Comparison: How do the natural color and false color composites differ in what they reveal? Which features are more prominent in each?
  4. False Color Advantage: What specific information does the false color composite reveal that is harder to see in the natural color composite?

📧 Lab Submission

Submit lab via email.

Subject: Lab 5 - Challenge Refreshers - [Your Name]

Submit:

A shareable URL to your Google Earth Engine script that includes:

  • Code to create both natural color and false color composites
  • Comments answering all four questions above
  • Proper visualization parameters for both layers
  • Descriptive layer names

Total: 50 Points