Volume 6, Issue 1 - Special Issue on Multi-sensor Systems in Engineering Geodesy and Navigation

Abstract. This paper demonstrates the performance of a deeply integrated GPS/inertial architecture under extreme canopy coverage, where traditional receiver technology fails to acquire and track GPS signals. GPS and inertial experimental data collected in various canopy coverage areas are applied to evaluate the system performance. Test results demonstrate that the deeply integrated approach enables reliable trajectory reconstruction capabilities and maintains sub-meter level of differential positioning precision for cases where the GPS signal is severely attenuated by the canopy.

Abstract. As a result of the Real-Time IGS Pilot Project (RT-IGS) and the EUREF Real-Time Analysis Project (EUREF-RT), real-time GNSS satellite orbit and clock corrections to broadcast ephemeris, the so-called real-time broadcast corrections (BC), have become available for the application in precise point positioning (PPP). The real-time BCs are currently available in global as well as in regional reference frames. In this contribution the PPP usage and performances of these global and regional BCs are analysed for the Australian continent. We identify the limitations of the current regional BCs, which results in scale-induced biases, and show how they can be improved. We also present an alternative, more user friendly, approach for regional BCs. It provides PPP users with simple means to correct for the biases of the regional approach.

Abstract. This paper reports on investigation of measurement uncertainty in positioning of a terrestrial laser scanner with network RTK (Real-Time Kinematic) service provided by SWEPOS®, Swedish national network of permanent reference stations for GNSS (Global Navigation Satellite System). To simulate measurements by a scanner, a rotating flat bar fixed to a prism base, attached to a tribrach, was used. The tests have been carried out with both a rotating GNSS antenna (placed at different distances from the centre of rotation – radii) and a stationary antenna, under different time intervals (1–5 min). The results show that it is possible to achieve a standard uncertainty of less than 10 mm in plane and 16 mm in height, independently of the observation time and radius. Hence, network RTK can be used with advantage for precise direct georeferencing of point clouds, not only for determination of the position of the scanner, but also its orientation.

Abstract. The paper presents an iterative matching method to improve a direct geo-referencing approach for stationary terrestrial 3D laser scans by means of the positional and transformational uncertainties of two 3D point clouds. In this approach, a geo-referenced point cloud from a station inherits the following stochastic information: (1) transformational uncertainties from processed GNSS data through the Kalman filter and (2) positional uncertainties through the range and angular uncertainties from the terrestrial laser scanner as well as the incident angle of the laser beam to a surface. This stochastic information from two (pre-) geo-referenced 3D point clouds is implemented within a novel iterative matching algorithm, named Geo-referencing ICP with Helmert 3D transformation , for subsequent post-processing procedures such as segmentation and further calibration.

Abstract. The new generation RFID-Radar system provides the function of detecting the targets' locations with the measurements of range and angle using a reader and an antenna array to transmit and receive the RF signals. It enhances the application value for RFID when combined with the geospatial information. In this study, an information system embedded with a plan coordinate detection function was developed using the spatial data provided by the RFID-Radar system, to expand the application of indoor locating and meet the inventory management requirements. The in-house developed management system can work for processing the measurements detected by the RFID-Radar system, calculating the target's location, checking the target's status and analyzing the target's movement occurring between the two detecting epochs through a designed GUI (graphical user interface). The system has been tested to show an internal precision of 0.76 m for locating, based on the stability test of the range and angle measurements, and effectively demonstrates the functions for detecting the target's movement and archiving the inventory's management information with a database.

Abstract. In 2007 the Centre of Applied Geomatics of the Military University of Technology started measurements aimed at the monitoring of the dynamic state of the engineering structures using GNSS. The complexity of the problem forced us to apply an integrated system architecture. This concept is based on simultaneous measuring some selected elements of the structure using various types of sensors. Measurement information from numerous instruments is numerically integrated for determining the investigated parameter, e.g., the displacement vector. The CAG team performed the tests using such a system on the two permanent 500-meters long bridges, the temporary bridge crossing for military purposes and the 300-meters high chimney of the CHP station. The information about displacement vector together with the characteristic frequencies of the structure were determined using different techniques for increasing of its reliability. This paper presents the results of such tests, gives description of the integrated system designed in the CAG and brings forward with the plans for the future.