The paper proposes a new algorithm for constructing the velocity field, which is based on the study of the integral functional on the ensemble of trajectories. The resulting analytical representation of the variation of the integral functional gives us the gradient of the investigated functional. It allows to find the desired parameters using gradient methods, which determine the velocity field. This approach allows both optical flow and non-optical flow construction. The proposed algorithm can be used in the analysis of various images, in particular in radionuclide image processing.