Accuracy Evaluation of Real-Time GNSS Precision Positioning with RTX Trimble Technology

Abstract In this paper, authors present results of accuracy verification of the Trimble RTX technology. The GNSS receiver Spectra Precision SP60 was used in Cyprus (Kato Paphos Archaeological Park). To evaluate the accuracy of the receiver, two measuring test networks (consisting of 30 and 55 control points) were established. All points were determined in four measuring cycles. Additionally, in order to make more advanced analysis of the data, the bases were also measured by using another GNSS receiver - Geomax-Zenith 25. The point positions, in this case, were conducted in the local coordinate system of Kato Paphos Archaeological Park by using RTK positioning technology. To make a comparison, it was necessary to transform the coordinates based on different groups of fitting points. Analysis allowed to conclude that the Spectra Precision SP60 receiver and the RTX Trimble technology guarantee repeatable results (on the level of 4 cm) of point positioning measurements.

Download Full-text

A Real-Time and On-Line Visual System for Seamless Steel Pipe Linearity Measurement

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.295-296.393 ◽

2005 ◽

Vol 295-296 ◽

pp. 393-398

Author(s):

C.J. Liu ◽

Xue You Yang ◽

Ji Gui Zhu ◽

S.H. Ye

Keyword(s):

Coordinate System ◽

Real Time ◽

Local Coordinate System ◽

Steel Pipe ◽

Sensor Calibration ◽

Steel Pipes ◽

Global Calibration ◽

On Line ◽

Linearity Error ◽

Seamless Steel

Linearity is a very important parameter for seamless steel pipes. A real-time and on-line visual measurement system for seamless steel pipe linearity is presented. The system consists of several structured-light visual sensors. Each sensor can achieve the coordinate of the center of partial steel pipe in its local coordinate system. Through global calibration, all coordinates measured can be transformed into an integrated coordinate system. The linearity error of steel pipe can be assessed. This method can fulfill 100% on-line and real-time linearity measurement. A pair structure-light sensor is designed to improve accuracy and a suspension-wires method for sensor calibration and global calibration is used. Through experiments, it shows that the method not only meets the need of precise calibration but also significantly improves the efficiency and feasibility.

Download Full-text

Performance Comparison of Geo-Referencing a Radar Using Prism Method With Global Positioning System

10.20944/preprints202105.0276.v1 ◽

2021 ◽

Author(s):

Ebenhezer Mabotha ◽

Nkateko Mabunda

Keyword(s):

Coordinate System ◽

Real Time ◽

Local Coordinate System ◽

Performance Comparison ◽

Open Pit ◽

Open Pit Mining ◽

Matrix System ◽

Total Station ◽

Data Points ◽

Time Movement

Monitoring of the surface operations using movement and surveying radar (MSR) can prevent loss of life, equipment, production and loss of the mine. Slope monitoring using MSR is an important aspect of open-pit mining as it provides real-time movement of deformation data for the slope. It is therefore important that the radar is accurately geo-referenced in order to provide accurate real-time movement data. Geo-referencing is defined as the process of determining an instrument’s position (in the form of Easting, Northing, Height) as well as the orientation with respect to the mine’s local coordinate system. This helps in getting geo-referenced data points from the radar that are identified by a unique set of coordinates in relation to the mine’s coordinate system which allows the radar to track movement for a specific set of coordinates. In this research, we assess the performance of geo-referencing a radar using the total station method and compare it with the integration of Advance Navigation – Spatial Dual GPS system connected via RS422 on the MSR. This includes usage of the Spatial Dual navigation coordinates output to calculate the radar’s position relative to the mine local coordinates and mapping the radar’s azimuth, elevation and Range (Az, El and Rl) values to the measured pit-slope data points. Furthermore, a comparison of key attributes of both methods of geo-referencing is performed using a matrix system and giving an overall performance appraisal of both systems. Integrating a navigation system allows the radar to have an auto geo-referencing functionality that will reduce the time spent in completing this process. The findings reveal that the GPS obtained a higher score than the total station with prism method on the weighted matrix system. The total station was found to be more accurate than the GPS however, the deployment time for the GPS is quicker than that of the total station. This is important for different operation such as strip and open-pit mining to choose the preferred method of geo-referencing depending on the level of accuracy required.

Download Full-text

Absolute Positioning and Orientation of MLSS in a Subway Tunnel Based on Sparse Point-Assisted DR

Sensors ◽

10.3390/s20030645 ◽

2020 ◽

Vol 20 (3) ◽

pp. 645

Author(s):

Qian Wang ◽

Chao Tang ◽

Cuijun Dong ◽

Qingzhou Mao ◽

Fei Tang ◽

...

Keyword(s):

Coordinate System ◽

Laser Scanning ◽

Local Coordinate System ◽

Point Clouds ◽

Measurement Unit ◽

Scanning System ◽

Control Points ◽

Starting Point ◽

Inspection Work ◽

Subway Tunnels

When performing the inspection of subway tunnels, there is an immense amount of data to be collected and the time available for inspection is short; however, the requirement for inspection accuracy is high. In this study, a mobile laser scanning system (MLSS) was used for the inspection of subway tunnels, and the key technology of the positioning and orientation system (POS) was investigated. We utilized the inertial measurement unit (IMU) and the odometer as the core sensors of the POS. The initial attitude of the MLSS was obtained by using a static initial alignment method. Considering that there is no global navigation satellite system (GNSS) signal in a subway, the forward and backward dead reckoning (DR) algorithm was used to calculate the positions and attitudes of the MLSS from any starting point in two directions. While the MLSS passed by the control points distributed on both sides of the track, the local coordinates of the control points were transmitted to the center of the MLSS by using the ranging information of the laser scanner. Then, a four-parameter transformation method was used to correct the error of the POS and transform the 3-D state information of the MLSS from a navigation coordinate system (NCS) to a local coordinate system (LCS). This method can completely eliminate a MLSS’s dependence on GNSS signals, and the obtained positioning and attitude information can be used for point cloud data fusion to directly obtain the coordinates in the LCS. In a tunnel of the Beijing–Zhangjiakou high-speed railway, when the distance interval of the control points used for correction was 120 m, the accuracy of the 3-D coordinates of the point clouds was 8 mm, and the experiment also showed that it takes less than 4 h to complete all the inspection work for a 5–6 km long tunnel. Further, the results from the inspection work of Wuhan subway lines showed that when the distance intervals of the control points used for correction were 60 m, 120 m, 240 m, and 480 m, the accuracies of the 3-D coordinates of the point clouds in the local coordinate system were 4 mm, 6 mm, 7 mm, and 8 mm, respectively.

Download Full-text

SURVEY OF ARCHAEOLOGICAL SITES OF GORNY ALTAY USING UAV

Vestnik SSUGT (Siberian State University of Geosystems and Technologies) ◽

10.33764/2411-1759-2021-26-2-56-64 ◽

2021 ◽

Vol 26 (2) ◽

pp. 56-64

Author(s):

Evgeny P. Krupochkin ◽

◽

Sergei I. Sukhanov ◽

Dmitry A. Vorobyov ◽

◽

...

Keyword(s):

Coordinate System ◽

Unmanned Aerial Vehicles ◽

Local Coordinate System ◽

Archaeological Sites ◽

Control Points ◽

Heritage Sites ◽

Gps Survey ◽

Aerial Vehicles ◽

Russian Federa Tion

The article describes a methodology for determining the boundaries of archaeological sites using GPS survey and unmanned aerial vehicles (UAVs) with subsequent registration in the cadastral record. The method of georeferencing and photogrammetric processing of orthophotomaps using a system of control points has been tested. The digital photogrammetric program Agisoft Metashape (company Agisoft LLC, St. Petersburg) was chosen for the research. By means the program an orthomosaic was obtained with georeferencing with the Local Coordinate System (LCS-04). The result of the work was the construction of topographic plans and the determination of the boundaries of archaeological sites in accordance with the "Methodology for determining the boundaries of the territories of archaeologi-cal heritage sites, recommended for use by the letter of the Ministry of Culture of the Russian Federa-tion No. 12-01- 39/05-AB dated 27.01.2012".

Download Full-text

Design of a Smartphone Indoor Positioning Dynamic Ground Truth Reference System Using Robust Visual Encoded Targets

Sensors ◽

10.3390/s19051261 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1261 ◽

Cited By ~ 5

Author(s):

Xuan Liao ◽

Ruizhi Chen ◽

Ming Li ◽

Bingxuan Guo ◽

Xiaoji Niu ◽

...

Keyword(s):

Real Time ◽

High Precision ◽

Reference System ◽

Local Coordinate System ◽

Recognition Rate ◽

Ground Truth ◽

Indoor Positioning ◽

Accuracy Evaluation ◽

Base Points ◽

Time Accuracy

Smartphone indoor positioning ground truth is difficult to directly, dynamically, and precisely measure in real-time. To solve this problem, this paper proposes and implements a robust smartphone high-precision indoor positioning dynamic real-time ground truth reference system using color visual scatter-encoded targets based on machine vision and photogrammetry. First, a kind of novel high-precision color vision scatter-encoded patterns with a robust recognition rate is designed. Then we use a smartphone to obtain a sequence of images of an experimental room and extract the base points of the color visual scatter-encoded patterns from the sequence images to establish the indoor local coordinate system of the encoded targets. Finally, we use a high-efficiency algorithm to decode the targets of a real-time dynamic shooting image to obtain accurate instantaneous pose information of a smartphone camera and establish the high-precision and high-availability smartphone indoor positioning direct ground truth reference system for preliminary real-time accuracy evaluation of other smartphone positioning technologies. The experimental results show that the encoded targets of the color visual scatter-encoded pattern designed in this paper are easy to detect and identify, and the layout is simple and affordable. It can accurately and quickly solve the dynamic instantaneous pose of a smartphone camera to complete the self-positioning of the smartphone according to the artificial scatter feature visual positioning technology. It is a fast, efficient and low-cost accuracy-evaluation method for smartphone indoor positioning.

Download Full-text

Determining the Suitable Number of Ground Control Points for UAS Images Georeferencing by Varying Number and Spatial Distribution

Remote Sensing ◽

10.3390/rs12050876 ◽

2020 ◽

Vol 12 (5) ◽

pp. 876 ◽

Cited By ~ 5

Author(s):

Valeria-Ersilia Oniga ◽

Ana-Ioana Breaban ◽

Norbert Pfeifer ◽

Constantin Chirila

Keyword(s):

Coordinate System ◽

High Precision ◽

Random Distribution ◽

Low Cost ◽

Local Coordinate System ◽

Point Clouds ◽

Ground Control ◽

Unmanned Aerial Systems ◽

Control Points ◽

Ground Control Points

Currently, products that are obtained by Unmanned Aerial Systems (UAS) image processing based on structure-from-motion photogrammetry (SfM) are being investigated for use in high precision projects. Independent of the georeferencing process being done directly or indirectly, Ground Control Points (GCPs) are needed to increase the accuracy of the obtained products. A minimum of three GCPs is required to bring the results into a desired coordinate system through the indirect georeferencing process, but it is well known that increasing the number of GCPs will lead to a higher accuracy of the final results. The aim of this study is to find the suitable number of GCPs to derive high precision results and what is the effect of GCPs systematic or stratified random distribution on the accuracy of the georeferencing process and the final products, respectively. The case study involves an urban area of about 1 ha that was photographed with a low-cost UAS, namely, the DJI Phantom 3 Standard, at 28 m above ground. The camera was oriented in a nadiral position and 300 points were measured using a total station in a local coordinate system. The UAS images were processed using the 3DF Zephyr software performing a full BBA with a variable number of GCPs i.e., from four up to 150, while the number and the spatial location of check points (ChPs) was kept constant i.e., 150 for each independent distribution. In addition, the systematic and stratified random distribution of GCPs and ChPs spatial positions was analysed. Furthermore, the point clouds and the mesh surfaces that were automatically derived were compared with a terrestrial laser scanner (TLS) point cloud while also considering three test areas: two inside the area defined by GCPs and one outside the area. The results expressed a clear overview of the number of GCPs needed for the indirect georeferencing process with minimum influence on the final results. The RMSE can be reduced down to 50% when switching from four to 20 GCPs, whereas a higher number of GCPs only slightly improves the results.

Download Full-text

Establishment of local coordinate systems in the transition to the geodetic system of coordinates of GSK-2011

Geodesy and Cartography ◽

10.22389/0016-7126-2017-929-11-2-10 ◽

2017 ◽

Vol 929 (11) ◽

pp. 2-10

Author(s):

A.V. Vinogradov

Keyword(s):

Coordinate System ◽

Small Businesses ◽

Transition Period ◽

Local Coordinate System ◽

Initial Point ◽

Central Meridian ◽

Administrative District ◽

Local Networks ◽

Small Areas ◽

Geodetic System

Pretty before long there will be transition to the geodetic system of coordinates of GSK-2011. For the transition period it is necessary to develop a method of recalculating coordinates from one system to another. The existing methods of recalculating coordinates are designed for recalculating coordinate points of state geodetic networks (GGS) and geodetic local networks (GSS). For small areas (administrative districts, populated areas) simplified methods are more acceptable. You need to choose the resampling methods that can be applied in small businesses, performing surveying works. The article presents the the results of calculations of changes of coordinates of the same point in GSK-2011 and SC-95 in six-degree zones of Gauss projection. It was found that in each region values of the shifts changed to small ones. Therefore, it is possible to convert the coordinates of the points by the simplified formulae. For recalculation from the coordinates of GSK-2011 in SK-95 or local coordinate system (WCS) of the administrative district it is necessary to find the origin of coordinates, scale value and rotation of the coordinate axes. The error of the conversion shall not exceed 0,001 m. The coordinates of the initial point of the local coordinate system relative to the central meridian of the local coordinate system shall be added in the list of parameters of the transition from local coordinate system to the state one.

Download Full-text

Consistent co-rotational framework for Euler-Bernoulli and Timoshenko beam-column elements under distributed member loads

Advances in Structural Engineering ◽

10.1177/1369433220986632 ◽

2021 ◽

pp. 136943322098663

Author(s):

Yi-Qun Tang ◽

Wen-Feng Chen ◽

Yao-Peng Liu ◽

Siu-Lai Chan

Keyword(s):

Coordinate System ◽

Stiffness Matrix ◽

Traditional Method ◽

Local Coordinate System ◽

Frame Structures ◽

Global Coordinate System ◽

Single Element ◽

Geometrically Nonlinear ◽

Geometrically Nonlinear Analysis ◽

Geometric Stiffness

Conventional co-rotational formulations for geometrically nonlinear analysis are based on the assumption that the finite element is only subjected to nodal loads and as a result, they are not accurate for the elements under distributed member loads. The magnitude and direction of member loads are treated as constant in the global coordinate system, but they are essentially varying in the local coordinate system for the element undergoing a large rigid body rotation, leading to the change of nodal moments at element ends. Thus, there is a need to improve the co-rotational formulations to allow for the effect. This paper proposes a new consistent co-rotational formulation for both Euler-Bernoulli and Timoshenko two-dimensional beam-column elements subjected to distributed member loads. It is found that the equivalent nodal moments are affected by the element geometric change and consequently contribute to a part of geometric stiffness matrix. From this study, the results of both eigenvalue buckling and second-order direct analyses will be significantly improved. Several examples are used to verify the proposed formulation with comparison of the traditional method, which demonstrate the accuracy and reliability of the proposed method in buckling analysis of frame structures under distributed member loads using a single element per member.

Download Full-text

Simulation case study of deformations and landslides using real-time GNSS precise point positioning technique

Geomatics Natural Hazards and Risk ◽

10.1080/19475705.2015.1137243 ◽

2016 ◽

Vol 7 (6) ◽

pp. 1856-1873 ◽

Cited By ~ 6

Author(s):

Raquel M. Capilla ◽

José Luis Berné ◽

Angel Martín ◽

Raul Rodrigo

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Positioning Technique ◽

Point Positioning

Download Full-text

Precise Point Positioning Using the Regional BeiDou Navigation Satellite Constellation

Journal of Navigation ◽

10.1017/s0373463313000842 ◽

2014 ◽

Vol 67 (3) ◽

pp. 523-537 ◽

Cited By ~ 7

Author(s):

Aigong Xu ◽

Zongqiu Xu ◽

Xinchao Xu ◽

Huizhong Zhu ◽

Xin Sui ◽

...

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Satellite System ◽

Convergence Time ◽

Asia Pacific ◽

Satellite Orbits ◽

Navigation Satellite ◽

Asia Pacific Region ◽

Point Positioning

On 27 December 2012 it was announced officially that the Chinese Navigation Satellite System BeiDou (BDS) was able to provide operational services over the Asia-Pacific region. The quality of BDS observations was confirmed as comparable with those of GPS, and relative positioning in static and kinematic modes were also demonstrated to be very promising. As Precise Point Positioning (PPP) technology is widely recognized as a method of precise positioning service, especially in real-time, in this contribution we concentrate on the PPP performance using BDS data only. BDS PPP in static, kinematic and simulated real-time kinematic mode is carried out for a regional network with six stations equipped with GPS- and BDS-capable receivers, using precise satellite orbits and clocks estimated from a global BDS tracking network. To validate the derived positions and trajectories, they are compared to the daily PPP solution using GPS data. The assessment confirms that the performance of BDS PPP is very comparable with GPS in terms of both convergence time and accuracy.

Download Full-text