The ideal 3-D seismic survey would have offset and azimuth distributions which were spatially very consistent. This means that the fold would have to be high. Cost considerations, environmental concerns, topography, and the effects of surface infrastructure and other obstructions, usually result in the surface acquisition grid being quite coarsely sampled and the offset and azimuth distributions being less than uniform. These irregularities can cause difficulties in data processing and frequently result in significant spatial variations in the amplitudes and phase of the final data volume used for interpretation. Structural errors may also result. Because the variations in trace attributes follow the variations in the surface geometry used for the data acquisition, these effects cause an acquisition footprint or pattern of data acquisition lineations. Special processing algorithms may be required to minimize these effects, but they are almost always present at some level on every data set. Prior to the interpretation of any data volume the interpreter should become familiar with the acquisition geometry, the data processing flow, and potential artifacts that may have been produced. A careful balance between the spatial changes in trace attributes and the cost of the survey needs to be achieved during the design process.