Suitability Of 3D Dense Models For Rapid Mapping Strategies On Cultural Heritage Documentation And Conservation. Validation of metric and non-metric information extraction from integrated solutions.

This dissertation deals with the suitability of digital models for the 3D documentation of built heritage (BH), in terms of its resolution, measure and representation regarding the building’s morphology and state of conservation. Specifically, the research enquires into the 3D models’ consistency and validation, generated by new methodological developments of geomatics-integrated techniques for obtaining geospatial data, by means of rapid mapping solutions in 3D survey, generally with low-cost approaches, to obtain metric and non-metric definition of the historical structures. Starting from the bounding of the concept of user-oriented models in the reality-based modelling issues at the first part of the dissertation, the documentation of cultural heritage (CH) in critical contexts is defined as investigation workspace. The established workflows of the digital metric survey based on range-based and image-based sensors are analysed in the second part, and the possible integrated acquisition and processing phases on the point clouds data treatment for the surface model definition are proposed and validated. The assessment issues are weighted on employed techniques, well-established and more innovative, and on the initially introduced requirements about scale accuracy and achievable details. 

The aim of this research is thus to focus on the 3D model features and their confidence levels to define and classify the extracted multi-scale geometric and radiometric information that can be useful to be addressed toward interdisciplinary interventions on the state of conservation, on the damage mapping and assessment around cultural heritage assets. This content is bound around the 3D model, according to a multi-parameter framework that wants to cover the overall validation attributes, such as: operational efficiency or the practicality and sustainability of data achievement; reliability or the confidence level of the metric contents on the model; contents or the richness of the embedded data; completeness or the comprehensiveness of gatherable information. 

The extensive testing, addressed in the fourth part of the discussion, is based on a set of examples regarding the analysed BH typologies located in the different urban and landscape contexts, featured by increasing levels of critical issues. It aims is the supporting the comparative multi-parameter evaluation and validation in the central part of the dissertation. Herein, the validation of 3D models is proposed from integrated workflows which take into account consolidated approaches (like terrestrial laser scanning or close-range photogrammetry) flanked by rapid mapping strategies with the employment of alternative techniques (such as the UAV photogrammetry, in the nadir and oblique configurations, and the portable Mobile Mapping Systems). The information richness, according to a 3D integration perspective, demonstrates across the dataset presentation and the final discussion, the promising and flexible ability of documenting the morphology and material characterization of complex historical structures, even proving their aptitude to support the mapping of structures consistence and conservation in case of emergency and damage assessment.