This paper describes in detail the applicability of the developed ground-penetrating radar (GPR) model with a kinematic GPR and self-tracking (robotic) terrestrial positioning system (TPS) surveying ...setup (GPR-TPS model) for the acquisition, processing and visualisation of underground utility infrastructure (UUI) in a real urban environment. The integration of GPR with TPS can significantly improve the accuracy of UUI positioning in a real urban environment by means of efficient control of GPR trajectories. Two areas in the urban part of Celje in Slovenia were chosen. The accuracy of the kinematic GPR-TPS model was analysed by comparing the three-dimensional (3D) position of UUI given as reference values (true 3D position) from the officially consolidated cadastre of utility infrastructure in the Republic of Slovenia and those obtained by the GPR-TPS method. To determine the reference 3D position of the GPR antenna and UUI, the same positional and height geodetic network was used. Small unmanned aerial vehicles (UAV) were used for recording to provide a better spatial display of the results of UUI obtained with the GPR-TPS method. As demonstrated by the results, the kinematic GPR-TPS model for data acquisition can achieve an accuracy of fewer than 15 centimetres in a real urban environment.
Urban atmospheric environmental issues are commonly associated with the physical processes of urban surfaces. Much progress has been made on the building-resolving microscale atmospheric models, but ...a realistic representation of the physical processes of urban surfaces on those models is still lacking. This study presents a new microscale urban surface energy (MUSE) model for real urban meteorological and environmental applications that is capable of representing the urban radiative, convective, and conductive energy transfer processes along with their interactions, and that is directly compatible with the Cartesian grid microscale atmospheric models. The physical processes of shadow casting and radiative transfers were validated on an analytical accuracy level. The full capability of the model in simulating the three-dimensional surface heterogeneities in a real urban environment was tested for a hot summer day in August 2016 using the field measurements obtained from the Kongju National University campus, South Korea. The validation against the measurements showed that the model is capable of predicting surface temperatures and energy balance fluxes in a patch scale at the heterogeneous urban surfaces by virtue of the interactive representation of the urban physical processes. The excellent performance and flexible grid design emphasize the potential capabilities of the MUSE model for use in urban meteorological and environmental applications through the building-resolving microscale atmospheric models, such as computational fluid dynamics (CFD) and large-eddy simulations (LES).
In the field of mass-market location-based services, smartphones have become the mainstream terminals by their ubiquity, portability, and low cost. The release of GNSS raw observations in Android ...smart devices and the popularity of low-cost dual-frequency GNSS chipsets have greatly inspired the research on high-precision positioning for smartphones. In this contribution, we give the quality investigation results of the smartphone B1C and B2a observations of BDS-3 new signals for the first time and study in detail the characteristics of multi-frequency and multi-constellation smartphone raw observations in both static and kinematic situations. The results show that the accuracy of pseudorange and carrier phase in the L5 band is 2–5 times and 2 times higher than that in the L1 band, especially in kinematic situations. A multi-GNSS RTK positioning method for smartphones suitable for real kinematic conditions is proposed, and two specialized improvement strategies are given, including a comprehensive data quality control strategy combing prior and post-detection, and an improved method for constraining RTK float solutions in the position domain. Finally, multiple sets of experiments under different motion conditions and observation environments are carried out. In the playground, urban expressway, and urban main road tests, the DF-RTK position accuracy is at centimeter level, decimeter level, and 1-m level, respectively, and the ambiguity fixing rates are 87.1%, 55.9%, and 2.6%, respectively. Meanwhile, the SF-RTK positioning has a certain degree of decline for each performance indicator. It is demonstrated that smartphones have a great potential to achieve high-precision navigation and positioning in real urban environments.
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