Smartphones for 3d model reconstruction

Today, it is possible to get three-dimensional information about the environment in the form of point clouds in a quick and easy way thanks to various types of existing sensors, like Laser Imaging Detection and Ranging (LiDAR), Red Green and Blues (RGB), Red-Green-Blue-Depth (RGB-D) sensors etc.., but also smartphones. Unlike the past, when the three-dimensional data acquisition tools were very expensive, they required to carefully planning the survey and they were used mainly by experienced users, today these sensors are widely available on the mass market at low prices allowing to get suitable results for different types of applications. Smartphones can now be easily mounted on UAV (Unmanned Aerial Vehicle) and UGV (Unmanned Ground Vehicle) systems in such a way that, potentially, anyone can access the data acquisition and extraction of 3D information, and, the advantage of using these techniques lies in the fact that it is possible to exploit the radiometric information contained in 2D image pixels using different strategies, like stereo matching and the structure from motion approach. Since, in recent years, smartphones devices have had a great improvement and the embedded sensors are becoming more efficient in terms of accuracy and reliability, this chapter attempts to analyse the complexity of the use of these kind of sensors for 3D reconstruction, but which require a lot of a priori knowledge of the internal sensors (e.g. camera calibration, data extraction, etc..) to reach stable results (e.g. camera calibration, data extraction, etc..). It will be briefly described how these technologies are categorized with the aim of highlighting the differences of the final products obtained according to the sensors used and of evaluating their performances in different environments.