The computation of the 2-D motion field from a sequence of images is one of the key tasks of many vision systems. Analysis and interpretation of flow fields is in general a complex task. One of the most interesting problems is to locate critical points in the motion field. The main theme of this thesis is the identification of critical points in motion fields, which have a physical significance for the corresponding application. The discrete Hodge Helmholtz decomposition is a vector decomposition algorithm which is used in this thesis for locating critical points in a motion field. Automatic processing of meteorological satellite data is a major field of research. In this context we propose a robust method for automatically detecting and tracking a hurricane eye over a sequence of satellite images. The hurricane eye is a rotational center and is detected as a critical point in the motion field extracted from a hurricane image sequence. The ridge and valley structure in a fingerprint image can be represented as a vector field. In this thesis, we develop a technique to detect the point of maximum curvature in the fingerprint ridge structure. This is done by analyzing the corresponding vector field and identifying the critical point that corresponds to the maximum curvature point. This point serves as a reference point for the registration of fingerprint images. Cardiac optical mapping is a relatively new technique for imaging the electrical activity on cardiac tissue. We present different techniques for the analysis of these optically mapped videos. Wavefront morphology and its relation to propagation velocity is studied and physical parameters of the cardiac tissue are predicted. We also compare two different techniques for velocity vector analysis.