Texture Mapping

Once alignment of the 3D object's anchor points is complete, the eyes, nose and mouth of the 3D model are aligned with the eyes, nose and mouth of the face in the 2D image. The transformation, Equation , can then be computed. Each point in the 3D object undergoes this transformation to determine its locus relative to the 2D image. Essentially, the 3D object's range data points are rotated, translated and stretched to superimpose the 2D face's intensity points. It is then possible to compute the projection of the 3D range model onto the 2D plane and to associate each of its range data points with a corresponding 2D plane point. Each projected 3D range point can then be ``colorized'' by the intensity value of the 2D plane point (or pixel) it intersects. The end result is a 3D model which is ``coated'' with the textural data of the face in the 2D image (see Figure ).

  

Figure 4.12: The 3D model coated with an intensity image's face.