1. A computer-implemented method of creating a polygon-based three-dimensional (3D) model from a two-dimensional (2D) pixel-based image, the method comprising: creating an inflatable polygon-based 3D image, by a vectorizing module running on one or more processors of one or more computer systems, based on a 2D pixel-based input image by representing pixels making up the 2D pixel-based input image as polygons; and extruding the inflatable polygon-based 3D image by generating z-coordinate values for reference points associated with the polygons, by an extrusion module running on the one or more processors, based upon a biased diffusion process.