Change Detection

Purpose

Describe the main ways remote sensing can detect and interpret differences between places, dates, and conditions.

Outline

• Change as difference, trend, threshold, or class transition
• Pre-event and post-event comparison
• Normal variation versus meaningful change
• Sensor consistency, seasonality, and atmospheric effects
• Validation and uncertainty in detected changes

Later Examples

• Comparing before and after imagery for disturbance
• Detecting vegetation loss with a simple index difference
• Summarizing class transitions within an area