*Article* **3D Thermal Imaging System with Decoupled Acquisition for Industrial and Cultural Heritage Applications**

#### **Ivo Campione 1,\*, Francesca Lucchi 1, Nicola Santopuoli 2 and Leonardo Seccia 3**


Received: 18 December 2019; Accepted: 22 January 2020; Published: 23 January 2020

**Abstract:** Three-dimensional thermography is a recent technique—with various fields of application—that consists of combining thermography with 3D spatial data in order to obtain 3D thermograms, high information objects that allow one to overcome some limitations of 2D thermograms, to enhance the thermal monitoring and the detection of abnormalities. In this paper we present an integration methodology that can be applied to merge data acquired from a generic thermal camera and a generic laser scanner, and has the peculiarity of keeping the two devices completely decoupled and independent, so that thermal and geometrical data can be acquired at different times and no rigid link is needed between the two devices. In this way, the stand-alone capability of each device is not affected, and the data fusion is applied only when necessary. In the second part, the real effectiveness of our approach is tested on a 3D-printed object properly designed. Furthermore, one example of an application of our methodology in the cultural heritage field is presented, with an eye to preservation and restoration: the integration is applied to a marble statue called Madonna with the Child, a fine work of the Florentine sculptor Agostino di Duccio (1418–1481). The results sugges<sup>t</sup> that the method can be successfully applicable to a large set of scenarios. However, additional tests are needed to improve the robustness.

**Keywords:** 3D thermography; thermal imaging; laser scanning; integration methodology; extrinsic calibration; decoupled acquisition; heritage conservation
