Showing papers in "Journal of Surveying Engineering-asce in 2017"
TL;DR: In this paper, the influence of flight altitude, terrain morphology, and the number of ground control points (GCPs) on digital surface model (DSM) and orthoimage accuracies obtained with UAV photogrammetry was explored.
Abstract: This paper explores the influence of flight altitude, terrain morphology, and the number of ground control points (GCPs) on digital surface model (DSM) and orthoimage accuracies obtained with unmanned aerial vehicle (UAV) photogrammetry. For this study, 60 photogrammetric projects were carried out considering five terrain morphologies, four flight altitudes (i.e., 50, 80, 100, and 120 m), and three different numbers of GCPs (i.e., 3, 5, and 10). The UAV was a rotatory wing platform with eight motors, and the sensor was a nonmetric mirrorless reflex camera. The root-mean-square error (RMSE) was used to assess the accuracy of the DSM (Z component) and orthophotos (X, Y, and XY components RMSEX, RMSEY, and RMSEXY, respectively). The results show that RMSEX, RMSEY, and RMSEXY were not influenced by flight altitude or terrain morphology. For horizontal accuracy, differences between terrain morphologies were observed only when 5 or 10 GCPs were used, which were the best accuracies for the flattest morph...
105 citations
TL;DR: In this article, a low-cost multisensor integrated navigation system was developed for a quadrotor aerial vehicle (QAV), which integrates a global positioning system (GPS) module, triaxial gyroscope, accelerometer, magnetometer, and digital barometer.
Abstract: The performance of navigation sensors may be seriously affected by the operating rotors of a drone. To address this kind of disturbance, a low-cost multisensor integrated navigation system was developed for a quadrotor aerial vehicle (QAV). The navigation board integrates a global positioning system (GPS) module, triaxial gyroscope, accelerometer, magnetometer, and a digital barometer. The sensors’ outputs were mathematically modeled and subsequently used in the integration Kalman filter. The data processing consisted of several steps: prefiltering, centralized filtering, and feedback. On the basis of onboard tests, the stochastic models of sensors were established in the presence of vibration, revolution, and ventilation caused by the QAV rotor’s operation, and in particular, its electromagnetic and aerodynamic characteristics. Flight experiments indicate that the proposed integrated navigation system can significantly improve flight accuracy and reliability.
54 citations
35 citations
TL;DR: In this paper, the free Online Positioning User Service (OPUS) was used to study land subsidence in the greater Houston area for over two decades (1993-2016).
Abstract: Global positioning system (GPS) techniques have been applied to study land subsidence in the greater Houston area for over two decades (1993–2016). The free Online Positioning User Service ...
34 citations
TL;DR: This paper proposes a new method that identifies the unstable points of a network based on the generalized likelihood ratio (GLR) test, called the simultaneous adjustment of two epochs (SATE) method, which is applicable to one-, two-, or three-dimensional deformation networks with any type of observations.
Abstract: An important issue in deformation analysis is identification of (un)stable points in a monitoring network. This paper proposes a new method that identifies the unstable points of a network based on the generalized likelihood ratio (GLR) test. The method, which simultaneously uses the observations of two epochs, is called the simultaneous adjustment of two epochs (SATE) method. The existing methods apply individual least-squares adjustment to the observations of each epoch. SATE is applicable to one-, two-, or three-dimensional deformation networks with any type of observations, including distances, angles, global positioning system (GPS) baselines, and height difference. To investigate the performance of the proposed method, observations of a real GPS deformation-monitoring network were used. The results for unstable points identification are identical to those of the existing methods. Furthermore, a few simulation case studies were used to evaluate the efficacy of the proposed method. The simulat...
28 citations
26 citations
TL;DR: In this paper, the authors proposed a weighted total least squares (WTLS) method to adjust an errors-in-variables (EIV) model containing random errors both in the observation vector and in the coefficient matrix.
Abstract: Weighted total least squares (WTLS) has been widely used as a standard method to optimally adjust an errors-in-variables (EIV) model containing random errors both in the observation vector and in the coefficient matrix. An earlier work provided a simple and flexible formulation forWTLS based on the standard least-squares (SLS) theory. The formulation allows one to directly apply the available SLS theory to the EIV models. Among such applications, this contribution formulates the WTLS problem subject to weighted or hard linear(ized) equality constraints on unknown parameters. The constraints are to be properly incorporated into the system of equations in an EIV model of which a general structure for the (singular) covariance matrix QA of the coefficient matrix is used. The formulation can easily take into consideration any number of weighted linear and nonlinear constraints. Hard constraints turn out to be a special case of the general formulation of the weighted constraints. Because the formulation is based on the SLS theory, the method automatically approximates the covariance matrix of the estimates from which the precision of the constrained estimates can be obtained. Three numerical examples with different scenarios are used to demonstrate the efficacy of the proposed algorithm for geodetic applications. DOI: 10.1061/(ASCE)SU.1943-5428.0000239.© 2017 American Society of Civil Engineers. Author keywords: Weighted total least squares (WTLS); Errors-in-variables (EIV) model; Linear equality constraints; Two-dimensional (2D) affine transformation.
23 citations
TL;DR: This data indicates that cooperative networks in low-cost unmanned aerial vehicles (UAVs) are attracting researchers because of their potential to enhance UAV performance.
Abstract: Cooperative networks of low-cost unmanned aerial vehicles (UAVs) are attracting researchers because of their potential to enhance UAV performance. Cooperative networks can be used in many a...
22 citations
22 citations
TL;DR: In this article, track survey cars are used to measure the parameters of the geometric quality of the tracks in long sectors, whereas traditional surveying methods (TSMs) or an automated measuring system based on a track-surveying trolley assisted by a robotic total...
Abstract: Maintenance of the rail track plays an important role in the policies that promote railway transport in the European Union. Each member state has its own railway infrastructure manager that is regulated by the standards set by the European Committee for Standardization (CEN). The standards define three levels for the track geometric quality: the alert limit (AL), the intervention limit (IL), and the immediate action limit (IAL). In the United States, the Federal Railroad Administration (FRA) manages the railroad safety and national rail transportation policy. They classify nine classes of tracks depending on the maximum allowable speed for freight and passenger trains; each classification has its own track geometric limits from nominal values. Usually, track-survey cars are used to measure the parameters of the geometric quality of the tracks in long sectors, whereas traditional surveying methods (TSMs) or an automated measuring system based on a track-surveying trolley assisted by a robotic total...
21 citations
TL;DR: With standard deviations of a few 0.01 mm for the estimated three-dimensional coordinates, it is demonstrated that the telescope camera of a modern IATS can be used as a highly accurate measurement sensor.
Abstract: Video theodolites were used in the 1980s for highly accurate, automated measurements. However, they disappeared from the market and research on these instruments was done by only a few institutions using self-made prototypes. Because of the release of new-generation image-assisted total stations (IATS) by different manufacturers since 2004, these instruments have become relevant again for broader user groups. In this article, different error sources that occur when working with an IATS are assessed. The theoretical origins of these errors are discussed, their dependence on the measurement geometry is worked out, and strategies for avoidance and modeling are provided. In experimental geodetic network measurements, the impact of the different error sources on the results are evaluated. With standard deviations of a few 0.01 mm for the estimated three-dimensional (3D) coordinates, it is demonstrated that the telescope camera of a modern IATS can be used as a highly accurate measurement sensor.
TL;DR: Lin et al. as mentioned in this paper proposed two structured total least squares (STLS) algorithms named constrained TLS (CTLS) and structured TLS normalization (STLN) to solve the linearly structured EIV (LSEIV) model.
Abstract: The paper focuses on a specific errors-in-variables (EIV) model named the linearly structured EIV (LSEIV) model in which all the random elements of design matrix are in a linear combination of an input vector with random errors. Two existing structured total least-squares (STLS) algorithms named constrained TLS (CTLS) and structured TLS normalization (STLN) are introduced to solve the LSEIV model by treating the input and output vectors as the noisy structure vectors. For comparison purposes, the weighted TLS (WTLS) method is also performed based on the partial EIV model. Approximated accuracy assessment methods are also presented. The plane fitting and Bursa transformation examples are illustrated to demonstrate the accuracy and computational efficiency performance of the proposed algorithms. It shows that the proposed STLS and WTLS algorithms can achieve the same accuracy if the dispersion matrix of the WTLS method is constructed based on the partial EIV model.
TL;DR: The heading solution from the dual-antenna configuration of the Spatial Dual was found to be more stable than the heading obtained with the reference SPANIMU, and the MTi-G-700 achieved a better roll/pitch accuracy.
Abstract: Small-sized unmanned aircraft systems (UAS) are restricted to use only lightweight microelectromechanical systems (MEMS)- based inertial measurement units (IMUs) due to their limited payload capacity. Still, some UAS-based geospatial remote sensing applications, such as airborne spectroscopy or laser scanning, require high accuracy pose (position and orientation) determination of the onboard sensor payload. This study presents ground-based experiments investigating the pose accuracy of two MEMS-based IMUs: the single-antennaMTi-G-700 (Xsens, Enschede, Netherlands) and the dual-antenna/dual-frequency Spatial Dual IMU (Advanced Navigation, Sydney, Australia)/global navigation satellite system (GNSS).A tightly coupled and postprocessed pose solution froma fiberoptic gyroscope (FOG)-based NovAtel synchronized position attitude navigation (SPAN) IMU (NovAtel, Calgary, Canada) served as a reference to evaluate the performance of the two IMUs under investigation. Results revealed a better position solution for the Spatial Dual, and the MTi-G-700 achieved a better roll/pitch accuracy. Most importantly, the heading solution from the dual-antenna configuration of the Spatial Dual was found to be more stable than the heading obtained with the reference SPANIMU.
TL;DR: In this paper, a workshop composed of 193 civil engineering students, 35 belonging to a control group, was conducted to determine whether spatial orientation skills can be developed through map reading and the virtual way-finding experience.
Abstract: Engineers use spatial information. Mapping and wayfinding in the real world are activities that use spatial orientation skills. A set of resources available on the Internet whereby engineers work with maps and spatial georeferenced information is termed geographic information science (GISc), which allows the use of mapping and exploratory navigation with maps and a continuous three-dimensional (3D) digital image of the real world to simulate navigation at a ground-level perspective. In this case study, a workshop composed of 193 civil engineering students, 35 belonging to a control group, was conducted to determine whether spatial orientation skills can be developed through map reading and the virtual wayfinding experience. After the workshop, the results showed a significant improvement in the spatial orientation skill, ranging between a minimum of 14.56° and a maximum of 26.61° rank in the Perspective Taking/Spatial Orientation Test: training had a positive impact on the development of spatial o...
TL;DR: In this article, a ray-tracing method for deriving the effect of instrumental systematic errors in terrestrial laser scanner (TLS) instruments is proposed, which can be effectively compensated for by model variables already inherent to the augmented TLS positioning equations.
Abstract: A new ray-tracing method for deriving the effect of instrumental systematic errors in terrestrial laser scanner (TLS) instruments is proposed. Three cases of mirror inclination error for the panoramic scanner architecture are used as examples to demonstrate the applicability of the method. The results show that all three errors can be effectively compensated for by model variables already inherent to the augmented TLS positioning equations. Specifically, the effects can be compensated for by the collimation axis and trunnion axis error terms and the tertiary rotation angle of the exterior orientation parameters.
TL;DR: This data indicates that the acquisition of geometric information about objects by using a moving sensor platform has gained increasing popularity in the surveying community and is likely to be useful for future surveys.
Abstract: During the last few years, the acquisition of geometric information about objects by using a moving sensor platform has gained increasing popularity in the surveying community. A large numb...
TL;DR: In this paper, the optimum horizontal location of a total station with respect to two control points is analyzed for a single-input single-out (SISO) system. But at least two CPs must be available to determine the position and orientation of the total station.
Abstract: At least two control points (CPs) must be available to determine the position and orientation of a total station (TS). This paper analyzes the optimum horizontal location of the TS with respect to ...
TL;DR: In this paper, the authors proposed a new array-aided state-space RTK (SS-RTK) method, which is applicable to the single-frequency network data processing.
Abstract: The concept of real-time kinematic precise point positioning (PPP-RTK) is to achieve integer ambiguity resolution (IAR) at a single global navigation satellite system (GNSS) user by providing network-derived satellite phase biases (SPBs) in addition to the standard PPP corrections. The integerness of the user ambiguities gets recovered and resolved, obtaining high-precision position solutions with the aid of the precise carrier-phase observables. Most of current PPP-RTK methods focus on processing dual-frequency or multifrequency GNSS network observations. The new developing Indian regional navigation satellite system (IRNSS), however, provides only a single-frequency signal in L-band, and shares the L5 frequency with the American global positioning system (GPS), the European Galileo, and the Japanese quasi-zenith satellite system (QZSS). This contribution proposes a new array-aided state-space RTK (SS-RTK) method following the concept of PPP-RTK, which is applicable to the single-frequency network data processing. A small array of multi-GNSS stations, separated by a few meters, takes the role of reference station to provide a batch of single-frequency RTK corrections. Similar to PPP-RTK, the single-frequency stand-alone user ambiguities are a double-differenced (DD) form after applying the SS-RTK corrections. Based on the proposed array-aided SS-RTK concept, the authors analyze the capability of the single-receiver positioning with IAR using L5/E5a frequency observations from IRNSS, as well as GPS, Galileo, and QZSS. Results from real-data experiments demonstrate that even though stand-alone RTK using current IRNSS satellites is not yet possible, they effectively contribute to the tightly integrated multisystem RTK. By increasing the number of antennas in the array used for SS-RTK corrections, the user would achieve more precise and reliable positions. After increasing the dimension of the array to four antennas, a 4-10% improvement in the IAR success rate is experienced. Moreover, the convergence time of the float solutions, reaching a subdecimeter precision level, reduces from 30 to 40 min (single-antenna array) to about 20 min (four-antenna array).
TL;DR: The efficacy of the least-squares VCE (LS-VCE) to height determination is demonstrated and the algorithm is applied to real data sets to evaluate the EGM2008 and GGMplus Earth geopotential models and a regional geoid model (named IRGeoid10) in terms of agreement to the GPS/leveling observations.
Abstract: In the last few years, satellite-based positioning techniques, such as the Global Positioning System (GPS), proved their abilities in various geodetic fields. Height determination, as one of such applications, requires a more likely correct geoid model to provide reliable geoid heights for transformation of the ellipsoidal heights to orthometric heights. An important step is then to establish such a model by optimal combination of the available geoid models. This can be achieved via variance component estimation (VCE) methods, which provide appropriate weights to GPS and leveling observations as well as the geoid models. The authors demonstrate the efficacy of the least-squares VCE (LS-VCE) to this problem. The algorithm is applied to real data sets in Shahin-Shahr, Isfahan, Iran, to evaluate the EGM2008 and GGMplus Earth geopotential models and a regional geoid model (named IRGeoid10) in terms of agreement to the GPS/leveling observations and introduce the more likely correct model over the case-...
TL;DR: In this paper, the geodetic datum of a deformation monitoring network is defined using its reference points, and how deformation analysis is affected when reference points have been disassociated.
Abstract: The geodetic datum of a deformation monitoring network is defined using its reference points. This article discusses how deformation analysis is affected when reference points have been dis...
TL;DR: In this article, an inversion method of the atmospheric refraction coefficient based on a trigonometric leveling network is proposed to solve the issue of deformation measurements in which the measuring environment might be the same in different epochs, but it sometimes changes significantly.
Abstract: Deformation measurements are repeatable. Therefore, they are often performed with the same equipment, methods, and geometric conditions in different epochs. However, although the measuring environment might be the same in different epochs, it sometimes changes significantly. Of all environmental parameters (atmospheric pressure, temperature, etc.), the atmospheric refraction coefficient is the most significant. Because it is unstable and changeable, measurement accuracy is affected. To solve this issue, an inversion method of the atmospheric refraction coefficient based on a trigonometric leveling network is proposed. This method is based on a mathematical model of the atmospheric refraction coefficient with weighted values, which are determined according to the difference between direct and reversed elevations. Therefore, the weighted average height of the closure errors of all triangles are considered. By iterative calculation, the atmospheric refraction coefficient is estimated. The estimated a...
TL;DR: In this article, a linear modification of Huber's mean error function is proposed to fit a high-accuracy levelling network to points of the vertical national control network, the control points of which are unstable because of vertical terrain movements caused by underground mining.
Abstract: The purpose of this research was to fit a high-accuracy levelling network to points of the vertical national control network, the control points of which are unstable because of vertical terrain movements caused by underground mining. For this reason, the robust M-estimation is used to reduce a negative impact of control points with gross errors on the estimated parameters. Because it has been found that the classical nonlinear Huber mean error function does not lead to any reasonable solutions, a new error function, a linear modification of Huber’s function, is introduced here. Using this function, a consistent solution of the robust adjustment and correct values of the estimated parameters can be achieved. To validate the results, other robust weight functions proposed by other authors are implemented as well. The results obtained in the particular variants are very close to those obtained using the proposed linear modification of Huber’s function. Moreover, the authors propose an adjustment str...
TL;DR: This work presents a meta-modelling architecture suitable for 3D image recognition and 3D3D image analysis and shows the architecture’s role in image recognition, as well as investigates its applications in medicine and engineering.
Abstract: In recent years, three-dimensional (3D) models have been used in a large variety of applications, and the steadily growing capacity in both quality and quantity is increasing demand. To app...
TL;DR: A new method is proposed for data fusion of aerial images and lidar data to extract road features by utilizing color components, such as luminance, saturation, and hue, in hue/saturation/intensity and brightness/blue difference/red difference color spaces.
Abstract: This paper presents a new framework of road feature extraction from color component–based data fusion of aerial imagery and lidar data. The proposed framework consists of six procedures: (1) removal of elevated objects (e.g., buildings) from lidar data with a flatness index constraint; (2) removal of shadows and vegetation from aerial images using the Otsu segmentation; (3) data fusion of the modified lidar data and aerial images; (4) initial extraction of road features from the fused data; (5) refinement of road features to remove false positives and join up misclosures; and (6) final extraction of road surfaces and centerlines. A new method is proposed for data fusion of aerial images and lidar data to extract road features by utilizing color components, such as luminance, saturation, and hue, in hue/saturation/intensity and brightness/blue difference/red difference color spaces. A series of refinement processes, including hierarchical median filtering and k-nearest-neighborhood, are implemented...