Day 2—Advanced Stacks, Color, and Scaling
A common challenge encountered when dealing with real-world data is working with extremely large images and datasets. This section offers practical solutions to working with large images and image stacks. The images you'll be working with are, in fact, large. Please make sure you have completed the section on memory management in Day 1 Part 2 and that you have set the memory allocation for ImageJ as high as possible for the amount of RAM installed in your computer. If necessary, quit other applications to free up as much memory for ImageJ as possible.
Where possible, backup image files are provided in case you have difficulty downloading large datasets over your network connection. Be sure to read any instructions specific to those files that may depart from the printed instructions, such as different size and scale information for scaled-down versions of the images.
Day 2 Goals
- Become comfortable downloading Landsat images from USGS GloVis or Landsat Click and Pick.
- Locate and interpret metadata associated with image data.
- Calibrate an image using its spatial resolution.
- Compare and contrast the spectral data from different Landsat bands.
- Understand the memory constraints of working with large images and stacks.
- Appropriately scale and crop images.
Day 2 Tasks
- USGS GloVis or Landsat Click and Pick to download at least three bands of Landsat data.
- Read and explore metadata associated with image data.
- Use the spatial resolution given in the metadata to calibrate a landsat image and make measurements.
- Scale and crop large images, such as Landsat data.
- Create true and false color Landsat images by merging different spectral bands.