A method is provided that determines velocity encoding direction of volumetricimage data sets comprising three-directional velocity information (V0, V1, V2)of atarget volume, which involves:a) defining a coordinate system (X, Y, Z),b) determining all the possible arrangements of the three velocitycomponents (V0, V1, V2) along the three coordinate axes (X, Y, Z)c) determining reference point or points in the target volume eitherautomatically or upon user inputd) determining streamlines for each point for all possible combinations ofvelocity components as determined in b) ande) considering as velocity encoding direction the arrangement of the threevelocity components corresponding to the streamlines having the longest lengthora length above a thresholdA corresponding apparatus and computer program are also disclosed.
