## 4 Three-Dimensional Modelling by the SfM-MVS Approach
### Software for UAV Photogrammetry  
Using software based on SfM-MVS algorithms, it is possible to obtain 3D point clouds useful to build realistic 3D models, digital surface models, and other derived technical representations such as orthophotos, features, contours, etc. In recent years, there has been an increase in the development of new photogrammetric commercial software; as a consequence, more and more high-performance software packages are available on the market. In the following Table 7, a review of the main commercial photogrammetric software is reported. In addition, open-source software is being continuously developed by the scientific community [110]. Indeed, the development of open-source software is an important research direction in order to maximise efficiency in the construction of 3D models, make  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Software** & **Description** & **Reference** \\ \hline \multirow{6}{*}{Metashape} & Agisoft Metashape is a professional software that can perform photogrammetric processing of digital images and videos and generate 3D spatial data for use in GIS applications, cultural heritage documentation, environmental monitoring, and more. It allows the generation and export in different formats of point clouds, textured 3D models, high-resolution motophotos, digital elevation models, and contour lines, as well as the possibility of measuring distances, areas, and volumes thanks to tools integrated into the software. & \\ \hline \multirow{6}{*}{Metashape} & 3 DF Zephyr software is produced in Italy and distributed by 3 Dflow, a private consulting and software production company operating in the field of computer vision and image processing. It was founded in 2011 as a spin-off of the University of Verona and, in 2012, was recognised as a spin-off of the University of Udine. 3 DF Zephyr is an automatic photogrammetry software that enables the creation of a 3D survey using photographs or digital videos. It allows us to create and export meshes and point clouds in the most common 3D formats, generate video animations, orthophotos, digital terrain models, sections, and contour lines, and calculate angles, areas, and volumes. & \\ \hline \multirow{6}{*}{R AUTODESK RECAP} & ReCap software, owned by Autodesk, can convert digital images into 3D models or 2D drawings from aerial photogrammetric datasets or through close-up photogrammetry. The software makes it easy to create a point cloud or mesh ready for use with other CAD software or tools. AutoDesk ReCap Photo is part of the broader subscription programme, ReCap Pro is bundled with ReCap Pro as of 2019. ReCap Photo limits the amount of processing a single user can do by providing a limited number of ‘Cloud Credits’. & \\ \hline \multirow{6}{*}{_DIX4D_} & Pix4D is a software developed by the Computer Vision Lab in Switzerland and implemented for both the image acquisition phase through mobile apps available for Android and iOS and the image processing phase. Pix4 Dmapper generates point clouds, orthomosaics, and elevation models and is suitable for applications such as agriculture, surveying, architecture, and real estate by providing tools and instruments for measuring distances, areas, and volumes, enabling virtual inspections.