change detection

So far, we’ve been looking at how we can extract information from single images - that is, a snapshot of what an area looks like at a single point in time. One of the most powerful applications of remote sensing, however, is the ability to view large-scale changes over time - that is, to detect changes.

In this section, we’ll look at a few different examples of change detection - starting from visually inspecting the differences between images, to making multitemporal composites, to looking at entire time series of values over time.

• visual analysis of changes
  • false-color composites
  • individual bands
  • multi-temporal false color composites
• band maths and thresholding
  • interpreting changes
  • choosing a threshold
  • references and notes
• repeat classification
• change vector analysis
  • preparation
  • calculating change vectors
  • interpreting changes
  • next steps
  • notes and references
• time series analysis