Using Self Organizing Maps to Visualize Structural Change in Geographic Regions of Interest: Las Vegas across the Years

Time-series of satellite images reveal important information about changes in environmental conditions and natural or urban landscape structures that are of potential interest to citizens, historians, or policymakers. We applied a fast method of image analysis using Self Organized Maps (SOM) and, more specifically, the quantization error (QE), for the visualization of critical changes in satellite images of Las Vegas, generated across the years 1984-2009, a period of major restructuration of the urban landscape. The satellite images were subdivided into geographic regions of interest. As shown in previous work by the authors, the QE from the SOM output is a reliable measure of variability and local changes in image contents. In the present work, we show how the QE from SOM run on satellite images of specific geographic regions of interest can be exploited for visualizing structural change across time at a glance, and facilitate the interpretation of related demographic data for a specific time period. The method is fast and reliable, and can be implemented for a rapid detection of critical changes in contents of time series of large bodies of satellite images.