# Optimised Extraction of Archaeological Features from Full 3-D GPR Data
## 6 Conclusions  
We showed the advantages achievable when using full 3-D GPR data instead of 2-D or pseudo 3-D GPR archaeological surveys, giving examples of the importance of accurate data processing, in particular for the EM velocity field estimation and the migration algorithms.  
By using integrated attributes, it is possible to determine shapes and borders and characterise archaeological targets; amplitude-based and coherency are the most effective and promising attributes. A correct parametrization of the process is mandatory, as shown in the case of the coherency calculation. We found that a vertical window length close to the dominant wavelength of the data is usually the best trade-off between resolution on one side and stability of the results on the other. Volume attributes on a full 3-D GPR dataset allow us to recognize and map even complex archaeological targets by means of isosurfaces extracted from a few manually selected control points by autotracking procedures, which are available on commercial software originally developed for the analysis and interpretation of reflection seismic datasets. It is essential to compare results obtained using different attributes, exploiting and emphasizing different signal characteristics such as amplitude, phase continuity, and spectral behaviour, especially when data are characterized by low SNR. Selection of seeds is a quite subjective procedure that can potentially produce incorrect results. In our experience, the best approach is to first carefully analyse time- or depth-slices, then select seeds on the most promising and apparent structures. To achieve correct results, it is important to collect GPR data with a centimetric positioning accuracy that is guaranteed (in favourable conditions) by recent RTK GPS devices. Integration of geophysical data with DTM and photographs obtained with UAV surveys and georeferenced with the same coordinate system is a key factor in achieving the following:  
* Storage of all the data in the same digital suite;
* Integrated analyses and correlation of events with the results coming from the new excavated areas.  
Further achievements could be obtained by using MO datasets, allowing for more accurate velocity field definition and imaging, and by integrating GPR data with multispectral surveys from UAV when the expected depth of the archaeological targets is limited.  
Conceptualization, E.F., P.B., and R.Z.; methodology, E.F., A.M., G.C., D.M., S.P., and M.P.; data curation, E.F., A.M., D.M., S.P., and M.P.; writing--original draft preparation, E.F., A.M., and P.B.; writing--review and editing, all the authors; supervision, P.B. and R.Z. All authors have read and agreed to the published version of the manuscript.  
This research was founded by Fondazione Aquileia.  
Not applicable.  
**Data Availability Statement**: Geophysical data are available, upon specific request, from Esplora srl.  
We gratefully acknowledge Schlumberger through the University of Trieste, the Petrel\({}^{\circledR}\) interpretation package academic grant, as well as dGB Earth Sciences for making available for free the OpenDect software. Three anonymous reviewers are acknowledged for their useful comments and suggestions.  
The authors declare no conflict of interest.