3-D Shape Recovery Using A Deformable Model

The paper describes a method for recovering the 3-D shape of a moving object from a sequence of images. While following the motion of the object, a 3-D surface model, initialised to be spherical, progressively deforms itself under the action of simulated external forces applied to the model to drive its profile towards the object profile extracted from the image. An internal energy coupled to the model encourages a smooth and uniform deformation. The model is also constrained to be symmetrical about an plane parallel to the direction of motion. Poses for the model to correctly align with the object in 3-D are computed by using the motion trajectory of the object in the image plane and a non-linear least squares method. Experimental results are presented for recovery of shape models of vehicles. The resulting model represents the 3-D object shape, and may be used for several purposes including object recognition, tracking and visualisation.