A method and apparatus are provided for efficiently obtaining navigational position of a sensor array based on a correlation between images captured by the sensor array at successive points in time. This is achieved by first acquiring a reference frame through said sensor array, successively acquiring a sample frame through said sensor array. Correlation data representing a relationship between the sample frame and the reference frame is then generated and a displacement of a reference feature contained in both the reference frame and the sample frame is determined based on the correlation data. The correlation surface of the correlation data is modeled as a general two-dimensional Taylor series expansion. The method and apparatus of the present invention can be advantageously employed in a scanning device to provide efficient scheme for obtaining navigational information based on a comparison of image frames captured by a sensor array of the scanning device at successive points in time.