Initial Publication Date: July 20, 2011

Day 5—Bring It All Together Into an Investigation

By the Numbers

Landsat Histogram

The theme of Day 5 is "by the numbers"— In Part 1, you use math to manipulate images and produce new data by combining the data from mutliple image. In Part 2, you get the numbers out of digital images, gathering the data needed for the final step in the research process.

Day 5 Goals

  • Understand the difference between performing mathematical operations on vs. between images.
  • Understand the mathematical basis of contrast enhancement.
  • Be able to perform image math to create a Normalized Difference Vegetation Index (NDVI) image.
  • Interpret histograms.
  • Intersect regions of interest.
  • Threshold to select regions of interest.

Day 5 Tasks

  1. Add to, subtract from, multiply, and divide images by constants.
  2. Perform mathematical operations to enhance image contrast.
  3. Create a Normallized Difference Vegetation Index (NDVI) image.
  4. Apply a look up table to an image.
  5. Threshold satellite images to identify sea ice extents.
  6. Intersect the sea ice extents with study areas.
  7. Use the intersections to measure the sea ice in each study area.

Sources

1Adapted from Earth Exploration Toolbook chapter instructions under Creative Commons license Attribution-NonCommercial-ShareAlike 1.0.
2Adapted from Eyes in the Sky II online course materials, Copyright 2010, TERC. All rights reserved.
3New material developed for Earth Analysis Techniques, Copyright 2011, TERC. All rights reserved
4From Remote Sensing Math: A Brief Mathematical Guide by Dr. Sten Odenwald, NASA 2011.