remote sensing Article Studying the Construction of Floor Mosaics in the Roman Villa of Pisões (Portugal) Using Noninvasive Methods: High-Resolution 3D GPR and Photogrammetry Bento Caldeira 1,* , Rui Jorge Oliveira 2 , Teresa Teixidó 3 , José Fernando Borges 1 , Renato Henriques 4 , André Carneiro 5 and José Antonio Peña 3 1 Institute of Earth Sciences/Physics Department, University of Évora, Rua Romão Ramalho, 59, 7002-554 Évora, Portugal 2 Institute of Earth Sciences, University of Évora, Rua Romão Ramalho, 59, 7002-554 Évora, Portugal 3 Andalusian Institute of Geophysics, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain 4 Institute of Earth Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 5 Centre for Art History and Artistic Research/History and Archaeology Department, University of Évora, Largo dos Colegiais, 2, 7000-803 Évora, Portugal * Correspondence:
[email protected] Received: 29 June 2019; Accepted: 9 August 2019; Published: 12 August 2019 Abstract: Over the past decade, high-resolution noninvasive sensors have been widely used in explorations of the first few meters underground at archaeological sites. However, remote sensing actions aimed at the study of structural elements that require a very high resolution are rare. In this study, layer characterization of the floor mosaic substrate of the Pisões Roman archaeological site was carried out. This work was performed with two noninvasive techniques: 3D ground penetrating radar (3D GPR) operating with a 1.6 GHz central frequency antenna, which is a very high-resolution geophysical method, and photogrammetry with imagery obtained by an unmanned aerial vehicle (UAV), which is a very high-resolution optical method.