Using all available subsurface information in the design of a 3-D seismic survey, we can better adjust the acquisition effort to the demands of illumination of the target horizon. I present a method that poses the choice of the acquisition parameters as an integer optimization problem. Rays are shot from grid points on the target reflector at uniform opening and azimuth angles and their emergence positions at the surface are recorded. The optimization (an exhaustive search in this example) minimizes the distance between the ray emergence coordinates and the source and receiver coordinates of candidate geometries subject to appropriate geophysical and logistics constraints. I illustrate the method with a 3-D subsurface model that I created featuring a target reflector whose depth changes significantly across the survey area. I show that for this model the standard approach would lead to a design requiring 200 shots/km2 whereas the optimum design requires only 80 shots/km2 without sacrificing the illumination of the target at any depth or the logistics of acquisition.