This article describes a method for simulating the formation and the development of cracks on the surface of a shrinking volume. The simulated cracks are applied afterwards to any surface provided with a parameterization. The creation of a new crack is based on a distance map, and occurs in the locations of the maxima of this map. The 2D path of the cracks is precalculated by an appropriate algorithm which gives a graph of discrete ways, taking into account a possibly inhomogeneous thickness of the shrinking layer. The propagation of one crack is based on the respect of a given orientation for the crack. One of the originalities of our method is the calculation of the enlargement of each crack by a discrete shrinkage volume propagation. We consider the shrinking layer as a set of cubic cells which contain volumes of matter and pores. During the dessiccation process, the matter shrinks, creating what we call a ``shrinkage volume''. We propagate this shrinkage volume by summing it from the farthest to the nearest cell (according to the distance to the cracks), and we deduce the width of each edge of the cracks from the final sum on this edge. In this paper, we present this method in detail and we give images obtained from different simulations. Initially designed to help for the prediction of seedlings emergence in an agronomic environment, the method we present can also be applied to enhance the realism of virtual 3D objects.
simulation, computer graphics, terrain visualization, cracks, cellular automata, watershed, Dirichlet tessellation, 3D-meshes