How to extract NDVI from Landsat 8 Satellite Imagery Data in ArcGIS?

Introduction

This tutorial guides you through the process of extracting the Normalized Difference Vegetation Index (NDVI) from Landsat 8 satellite imagery using ArcGIS. NDVI is a crucial metric for assessing vegetation health and monitoring environmental changes. By following these steps, you will gain practical skills in remote sensing analysis, which can be applied in various fields, including public health and environmental management.

Step 1: Download Landsat Imagery Data

• Visit the USGS Earth Explorer website: glovis.usgs.gov
• Create an account or log in if you already have one.
• Search for your area of interest using the Path: 24 and Row: 36.
• Select the desired Landsat 8 imagery and download the data. Choose the appropriate level (e.g., Level 1) for accurate analysis.

Step 2: Unzip and Explore the Bands

• Locate the downloaded Landsat data on your computer.
• Use a file extraction tool (such as WinRAR or 7-Zip) to unzip the data.
• Open the unzipped folder to view the individual band files. Typical bands for Landsat 8 include:
  • Band 2 (Blue)
  • Band 3 (Green)
  • Band 4 (Red)
  • Band 5 (Near Infrared)
  • Band 6 (Shortwave Infrared)
  • Band 7 (Shortwave Infrared)

Step 3: Load the Data into ArcMap

• Open ArcMap and create a new project.
• Use the “Add Data” button to load the individual band files into the project.
• Ensure that all bands are correctly displayed in the table of contents.

Step 4: Create a Composite Band

• In ArcMap, go to the “Data Management” toolbox.
• Navigate to “Raster” and select “Composite Bands.”
• Choose the bands that you want to include in the composite (typically Bands 4, 3, and 2 for true color).
• Name the output file and click OK to generate the composite.

Step 5: Calculate NDVI

• NDVI is calculated using the formula:

  NDVI = (NIR - Red) / (NIR + Red)
  

• In ArcMap, open the “Raster Calculator” from the Spatial Analyst tools.
• Enter the following expression:

  ([Band_5] - [Band_4]) / ([Band_5] + [Band_4])
  

• Replace [Band_5] and [Band_4] with the names of your Near Infrared and Red bands as they appear in ArcMap.
• Name the output NDVI raster and click OK to perform the calculation.

Step 6: Analyze NDVI Results

• Once NDVI is calculated, visualize the NDVI raster.
• Apply color ramps for better interpretation, such as using a gradient from red (low NDVI values) to green (high NDVI values).
• Identify areas of healthy vegetation versus stressed vegetation based on NDVI values.

Step 7: Explore Applications of NDVI

• Understand how NDVI can be applied in various fields:
  • Public health studies to assess habitats of ticks and other vectors.
  • Agriculture for monitoring crop health and growth.
  • Environmental management for assessing land cover change.

Conclusion

You have now learned the steps to extract and analyze NDVI from Landsat 8 imagery using ArcGIS. This process opens doors to various applications in environmental science and public health. Consider exploring additional resources and tutorials to deepen your understanding of remote sensing analysis. For further data, you can download the associated datasets from GitHub.