Conversational twins: The virtual engineering assistants of

3d twinTouted as the world’s first dital twin of a country, the 3D simulation of Singapore is exquisite in its detail. Any point in the country can be inspected in 360° of clarity. Users can flyAbstract. In this article, we propose a 3D mobile crowdsensing (3D-MCS) framework aimed at sustainable urban dital twins (UDTs). The framework comprises four key mechanisms: