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This paper reports on a set of intensive interdisciplinary field operations by a Belgian team of Ghent University in 2007 in the Marche region of central Adriatic Italy. Most of the interventions, comprising geophysical prospections, geomorphologic observations, aerial photography, surface artifact surveys, excavations, topographic surveys and pottery studies, aim at a better understanding of the developing Romanisation of this part of Picenum and the rapid urbanization of the area from the late Republic onwards. Quite spectacular are the results of combined remote sensing work on such towns as the coastal colony Potentia and the interior municipium Trea, with unusually detailed mapping of the majority of public and private town structures. In Potentia these intrasite and peri-urban surveys are now also being checked in the field with focused excavations on a town gate and an amphora workshop. Also important are original contributions towards a better comprehension of the townlandscape nexus, involving the discovery of roads, cemeteries, aqueducts and quarries discovered near the four Roman cities. Finally new observations concerning the pre-Roman situation of centrally organized settlement and its links with the establishment of more Roman style towns, add much to the debate about the relatively late urbanization of this Adriatic region.

In this paper, the impact of spatial sample density and three-dimensional migration processing on the interpretation of archaeological ground-penetrating radar (GPR) data is assessed. First, the question of how to determine the sample interval required to take full advantage of the spatial resolution capabilities of GPR without oversampling is addressed. To this end, we transform a test profile into the frequency-wavenumber (f-k) domain and estimate the required sample interval from the wavenumber values. For the presented data set, collected at the Roman town Ammaia (Portugal), this resulted in a transect spacing approximately three times the distance prescribed by the λ min /4 criterion (where λ min is the minimum observed wavelength). Second, the effect of three-dimensional migration is assessed. The data set, sampled as prescribed by the analysis of the f-k plot, is migrated with two-and three-dimensional phase-shift algorithms, and the migrated results are compared with non-migrated data. It is shown that certain subtle features are better resolved by three-dimensional migration. Third, it is investigated whether three-dimensional migration following the application of an interpolation algorithm such as Delaunay triangulation or interpolation based on τ-p transform, can further relax spatial sampling requirements. For the GPR data shown in this article, it is demonstrated that interpolation and three-dimensional migration of slightly aliased data, collected with a transect spacing equal to five times the outcome of the λ min /4 criterion, still allow a faithful reconstruction of the original, non-aliased time-slices. Figure 5. Energy time-slices from between 31 and 32 ns, showing details from areas 1A and 1B, surveyed with a 0.05 m × 0.05 m grid spacing in east west and north south directions, respectively: (a and b) data after three-dimensional phase-shift migration; (c and d) data after two-dimensional phase-shift migration in in-line direction; (e and f) Unmigrated data. The large arrows show the direction of the survey lines. The numbers are explained in the text.

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