Abstract:

Two categories of spread models used for forest fire simulation, namely contiguous cellular model and wave propagation model, were strongly complemented each other in their advantages and limitations, which was utilized in the paper to design a spread model based on computer graphic techniques. In the new model, states of fire spread are expressed as a predefined gray level image. A series of fire shapes stored in metagraphic set are written to the gray level image according to given rules of raster operation while simulating the wave propagation of fire spread. Scan-line flood-fill algorithm is used to deal with the spread near some geographical elements with complex topological relations. Projection of fire shapes is translated into the combined transformation of graphic rotation and shear. The advantages and deficiencies of the model are discussed, including its effect on local distortion and aberration. By primary theoretical analysis and a calculation case, it is deduced that the new model can accomplish the simulation for forest fire faster than the previous models by more than one order of magnitude, while other performances of simulation are highly improved as well. Therefore, it can provide forest fire fighting with precise and overall predicted diagram of fire development in real time, not restricted by complexities of fire behaviors or geographical elements.

Key words: forest fire, computer simulation, spread model, graphics technique