A Fire Perimeter Expansion Algorithm-Based on Huygens Wavelet Propagation

Abstract

To model the spread of the perimeter of a wildfire, the perimeter can be regarded as a continuous curve, or more simply as a discrete number of points, which approximate the curve. Each point on the perimeter can be regarded as a point source which expands as a small ellipse. The parameters of each ellipse depend on the local fuel type, slope and meteorological conditions and the time step. According to Huygens' principle, the envelope of these ellipses describes the new perimeter. With discontinuous terrain and fuel, the perimeter may become complex, developing concavities and surrounding areas of low rate of spread. An algorithm which defines this envelope has been developed as part of the National Bushfire Model (a real-time computer application for personal computers).