Improving accuracy

Recall our small motion assumption

This is not exact • To do better, we need to add higher order terms back in:

This is a polynomial root finding problem

• Can solve using Newton’s method – Also known as Newton-Raphson method – For more on Newton-Raphson, see (first four pages) » http://www.ulib.org/webRoot/Books/Numerical_Recipes/bookcpdf/c9-4.pdf • Lucas-Kanade method does one iteration of Newton’s method – Better results are obtained via more iterations