Head Tracking Using a Textured Polygonal Model

We describe the use of a three-dimensional textured model of the human head under perspective projection to track a person’s face. The system is hand-initialized by projecting an image of the face onto a polygonal head model. Tracking is achieved by finding the six translation and rotation parameters to register the rendered images of the textured model with the video images. We find the parameters by mapping the derivative of the error with respect to the parameters to intensity gradients in the image. We use a robust estimator to pool the information and do gradient descent to find an error minimum.