Relating Visual Changes in Images with Spatial Metrics
Nina Lam, Guiyun Zhou, Wenxue Ju · 2008
Visualizing land cover and feature changes from time-series remote sensing images is the first and fundamental step in understanding the change dynamics of many geographic phenomena. In general, changes that are drastic and spatially concentrated can be discerned more easily, whereas small and gradual changes that scatter are very difficult to detect. Moreover, human visualization is not sufficient to detect changes continuously and rapidly. We need computation and measurement to support visualization and help identify where and what are the visual changes. Visual representation alone cannot satisfy analytical needs (Thomas and Cook 2005). Therefore, relating the change dynamics observed visually with quantitative measures that can be computed from the images is very much needed to enhance the visualization capability. These measures or metrics would enable automation and hence rapid and continuous monitoring, which is crucial to supporting timely decision-making and risk assessment especially during extreme events (e.g., terrorist attacks, hurricanes, forest fires, earthquakes, disease spread).