Abstract
Visualization of recursively defined concepts is a general problem that appears in many areas. For example, drought areas based on the Standardized Precipitation Index (SPI) and long-term air pollution areas based on safe and critical level standards are recursively defined concepts. In this paper, we develop a general and efficient repre-sentation and visualization method for recursively defined spatio-temporal concepts. We illustrate our general method by visualizing drought and pollution areas.