Urban Building Updates Monitoring Based on Sky Visibility Estimation from Satellite Signals

As the digital twins for the urban area, 3-D building models have been applied in many areas and their reliability has become more and more vital. In a fast-developing city, the scale of construction renewal is usually tremendous with a high frequency, which makes the existing 3-D building models easy to be out-of-date and introduces errors. In this article, we proposed a monitoring algorithm for building updates based on satellite signals. We use satellite measurements to estimate the sky visibility from building blockages. By comparing it to the sky visibility from the existing data set, we can obtain the direction of the building being updated. Finally, the building update directions detected from multiple agents are collaborated in a crowd-sourcing manner to estimate the overall update probability of buildings. A simulation and a real experiment are conducted to evaluate the performance of the proposed algorithm. The proposed monitoring algorithm is robust to sky visibility estimation accuracy, number of agents, and agent positioning error from the simulation analysis. In the real experiment, the building with updates can be accurately detected by the satellite measurements collected from a short pedestrian trajectory around this area.