Local and Relative Optical Flow Estimation

Abstract

In this paper, we deal with the fundamental equation of a optical flow estimation by gradient method. We introduce the fundamental equation keeps its form invariant in any coordinate systems, even if coordinates are time varying.
With the above fact, we can calculate a relative optical flow corresponding to the coordinate system, and/or local optical flow in the coordinate system spanned in a local area on the moving object, using the fundamental equation of the same form.
This kind of optical flow implies movements on the corresponding coordinate system. We call it the Local and Relative Optical Flow (LROF), and confirm it by simulation of some examples.
This method extremely saves calculation of optical flow estimation compared with the conventional method, since LROF needs a small calculation only on the region of interest.
LROF may be widely applicable to many problems for estimating movements in local area on an object moving or form-changing in scene, such as strain analysisses or motion estimations of muscle on some medical images.