Geodaysit 2023

The new concept of Digital Twins (DT) as a city model is interlinked with the Smart City applications on many levels, like interactivity between virtual model and real world, simulations and analysis of present and planned city, emergency planning and management to mention a few. The strength of DT is related to the incorporation of time as a fourth dimension, considering the time as a variable that modifies the data and the semantic information. The aim of this emerging concept DT is provide a physical infrastructure, data, information and procedures for the management of a complex system, in order to offer to the public administration a platform for designing, testing, simulations and analysis of present and planned city, and offer through web-sharing high quality urban 3D model as open data to all operators in Open Source (OS) environments. There are several applications to share on the web a 3D model, but the lack of a detailed and adequately sized development platform is a bottleneck in this contest. The purposes of this work are based on the Torino DT project, source data for the 3D model had been acquired from images and point clouds data sets from 2022. The first step after the acquisition phase have been the source data processing, in order to build up a 3D model of the entire city. There have been rapid technological developments in the field of photogrammetric and LiDAR techniques to produce detailed and accurate 3D models. 3D point clouds from the state of the art LiDAR and photogrammetry provides a powerful collection of geometric elements of a scene with their position, orientation and shape in the 3D space. There are numerous computer vision programs like 3D Zephyr, VisualSfM, meshroom, WebODm etc which offers OS solutions for the 3D reconstruction processing from 2D images. The processing capabilities of these open source solutions are comparable as compared to the commercial ones in terms of geometric features and information. These open source tools are adequate for the research purposes to explore the potential of 3D models from photogrammetry and LiDAR. 3D model is based on a reality mesh model with a specific and well-known work-flow. The next step is share, part of, the 3D model in OS environments that can be accessed with JavaScript code like Cesium platform. 3D web platforms analyzed in this work reflect the ever greater interest in OS software, interoperability and collaboration standards, in order to work in the openness ecosystem. This research field open the way to new opportunities, for instance DT as Open Data. The free availability of an urban 3D model, build up from the reality, could create a new order of opportunity for future model updates or utilizations, especially for real estate operators. Furthermore, particular attention has been paid to model update with collaborative and crowdsourcing solutions, with the perspective to develop a community able to use and update the 3D model.