Heart illnesses influence the functioning of the cardiac muscle and are the major causes of death in the world. Optic flow methods are essential tools to assess and quantify the contraction of the cardiac walls, but are hampered by the aperture problem. Harmonic phase (HARP) techniques measure the phase in magnetic resonance (MR) tagged images. Due to the regular geometry, patterns generated by a combination of HARPs and sine HARPs represent a suitable framework to extract landmark features. In this paper we introduce a new aperture-problem free method to study the cardiac motion by tracking multi-scale features such as maxima, minima, saddles and corners, on HARP and sine HARP tagged images.