1. A method for gathering materials on an ocean surface, comprising: determining, using a computer processor, an initial distribution of material based on observational sources; representing the material by a plurality of particles in a numerical ocean model; determining a plurality of trajectories for the numerical ocean model based on modeled surface currents data; computing a plurality of velocity gradients along a corresponding trajectory of the plurality of trajectories for each of the plurality of particles based on the initial distribution; computing a plurality of deformation tensors for each of the plurality of particles based on the plurality of velocity gradient; generating a dilation map for the plurality of particles based on a time step tensor of the plurality of deformation tensor for each of the plurality of particles; and monitoring collection of the plurality of particles based on the dilation map.