1. A method for generating an illumination map, comprising: receiving an earth model representing one or more properties of the earth; receiving a target area in the earth model; simulating a propagation of one or more wavefields from the target area, using a computer, such that a portion of the propagated wavefields extends to a potential seismic data acquisition region in the earth model; decomposing the simulated propagated wavefields into a plurality of beamlets separated according to specific directions; creating the illumination map based on one or more of the plurality of beamlets, wherein the illumination map represents attributes of the one or more of the plurality of beamlets; and creating a seismic survey design based on the attributes represented in the illumination map.