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; 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; and wherein the biased diffusion process employs an equation having general form as follows: z 0 , t + 1 = z 0 , t + D [ p + ∑ i = 1 n ⁢ ( z i , t - z 0 , t ) ] where, n represents a number of neighboring agents used as inputs for the biased diffusion process; z 0,t represents a diffusion value of a center agent; z i,t represents a diffusion value of a neighboring agent (i>0); D represents a diffusion coefficient; and p represents a pressure value.