The real impact and usefulness of this methodology arises in 3-D land seismic acquisition where the cost of the surveys oftentimes requires the design to be a compromise of the different subsurface parameters in different parts of the survey. The design is then kept constant for the whole area. By adapting the acquisition effort locally to the imaging demands of the subsurface we could in principle acquire better data at the same cost or perhaps even cheaper.
It is all too common in 3-D land data that significant obstacles force us to deviate from the original design. The common practice is to displace shots and receivers to alternative positions chosen to maintain, as much as possible, the uniformity of fold and the regularity of offsets and azimuth distribution. All sources and receivers are considered equally important to the subsurface image, which is probably not a good idea in general. The presence of large obstacles can be incorporated into the design procedure and alternative source and receiver locations chosen to optimize the regularity of the illumination as opposed to the regularity of fold, offset or azimuth distributions as is standard practice. It may very well happen that some shots in the excluded area turn out not to contribute significantly to the critical parts of the image and so can be simply ignored if they are difficult to replace. On the other hand, it may turn out that those shots are critical and then there are concrete reasons to make a stronger effort to acquire them.
In conclusion, we should be able to use all the available information when designing the acquisition of a new survey and make decisions with as much information as possible. Shifting the emphasis from surface parameters (fold, offsets and azimuths) to subsurface parameters (illumination) is a step in the right direction.