# Testing the Effectiveness of Voxels for Structural Analysis
## 1 Introduction  
To conduct diagnostic research geared toward assessing the cutting-edge stage of degradation and the ongoing charge of deterioration in particular cultural heritage (CH) sites, the implementation of remote non-destructive testing (NDTIs) is essential. Identifying the best method for correct analysis is essential. FEA is a technique used to model the strain conduct of gadgets and structures, using 3D CAD (Computer Aided Design) models made from Non-Uniform Rational B-splines (NURBS) surfaces, which constitute an appropriate geometry of the item being simulated [1, 2]. Within FEA software program (Ansys 19.2), mesh creation modules are utilized to convert a NURBS model, which consists entirely of its outside surfaces, into a volumetric model [3]. This volumetric version features nodes distributed all over the model, using tetrahedra or hexahedra. When applied to 3D analysis of cultural heritage, which changes over time, the use of geometric CAD models can lead to over-simplifications, resulting in misguided simulation effects. Presently, the 3D documentation of CH has drastically progressed due to the use of both active and passive sensors. The initial result of this process is a dense 3D point cloud, which is later converted into a triangular mesh. These models accurately represent the exterior surfaces of the surveyed items and have usually high resolution, meaning millions of triangular elements. However, this high density makes them unsuitable for direct use in FEA. It is necessaryto convert meshes into a volumetric model and reduce their density, as the processing effort increases rapidly with the number of nodes representing the simulated object in the computational complexity of the analysis. The model developed aims to simulate stress behavior and predict potential damage, which enhances protection efforts, but several challenges have to be faced and addressed: (a) the process of generating volume suitable for finite element analysis from raw 3D data lacks clear guidelines, which can significantly affect the results; (b) the 3D acquisition process is often a mismatch between geometric resolution and reliability of simulation results compared to the 3D model obtained from the process. FEA is commonly employed in engineering as a standard technique for structural evaluation. In the context of ancient structures, to mitigate the risk of error propagation, one viable approach is to create a volumetric model directly from a 3D point cloud. The primary concern is ensuring that the model created for FEA closely resembles the original structure. The established methodology utilizes NURBS surfaces to define the form of the object intended for simulation. However, applying this method to 3D cultural heritage models may introduce significant approximations, potentially resulting in inaccurate simulation outcomes. A review of previous studies indicates various strategies have been adopted: (a) employing a CAD modeler to develop a new model from the surface mesh derived from the acquired 3D data; (b) directly utilizing the triangular mesh for volumetric models; (c) creating a volume from the point cloud; (d) transitioning from reality-based 3D models to BIM/HBIM (Building/Heritage Building Information Modeling) for FEA; (e) developing a new tool. The first approach was applied to simulate the behavior of various cultural heritage buildings [4; 5; 6; 7], further refined by incorporating a few patches of reality-based surface meshes [8] and for both 2D facade models [9; 10] as well as 2D and 3D modeling [11; 12], which also involved a significant discretization of the model using both a 3D model and a 3D composite beam model [13].