The rate of the spread and shape of a forest fire front is a problem that has not been thoughtfully studied from a computer graphics perspective. Here, using physically based computer graphics modeling, we propose a model for the simulation of wildland fires over 3D complex terrain. The model is based on conservation laws of energy and species, which includes radiation convection, reaction and natural convection, and takes into account the endothermic and exothermic phases of this kind of phenomenon. As an application, a simulation of a wildland fire in the Ebro basin of Spain is presented. The results are visualized on synthetic imagery, obtained by using the digital model of the studied terrain plus its corresponding images acquired by the Spot 4 and LandSat TM satellites.