Reflectorless Total Station Research Articles

JUSTIFICATION OF THE ACCURACY OF GEODESIC WORKS DURING THE INSPECTION OF THE BRIDGE IN RIVNE

Bridges are important structures for the safe operation of roads, railways and pedestrian areas. The purpose of this work is to substantiate the accuracy of geodetic works during the inspection of bridges. There are no requirements for the accuracy of such works in state construction standards. The relevance of this problem consists in the fact that it is necessary to perform any geodetic work with optimal accuracy, which, on the one hand, excludes excessive costs for geodetic equipment, and on the other, guarantees the safe functioning of the engineering structure. Based on such calculations, it is possible to choose geodetic equipment with appropriate characteristics and select measurement methods. Three options for calculating the required accuracy of geodetic measurements are considered: by the deviation of the top of the piles from the design position in the plan, by the deviation of the top of the bridge supports from the vertical and by the limit deflection of the beams-slabs of the bridge floor. As values for the marginal errors of geodetic work, it is suggested to choose the smaller value of the three options. The developed method was tested during the survey of the bridge is on Joliot Curie Street in Rivne. Based on the calculation results, the ground survey method chosen using the free station method with an electronic reflectorless total station Leica TCR 405 ultra, which provides the necessary accuracy and is the most economical. All elements of the bridge have been coordinated and the geodesy survey of the upper part of the bridge and the surrounding area has been carry out. According to the results of geodetic works, the tilts of the column-piles, the deflections of the longitudinal load-bearing beams-panels were calculated, and the plan of the top of the bridge was constructed. So, the geodetic work performed provided a high-quality examination of the bridge and allowed construction engineers to formulate the measures necessary for the further safe operation of this bridge structure. The scientific novelty and practical significance of this work consists in the fact that a methodology has been developed for substantiating the accuracy of geodetic works during the inspection of bridge structures, which guarantees the safe functioning of the bridge structure.

Beam Deflection under Static Loading: Comparison Between Dial Gauge and Total Station Measurements

This paper presents the results of experimental findings for beam deflection measurements under static loading using dial gauges and a reflector-less Total Station. The ultimate objective of this work is to compare the performance of the Total Station with respect to the Dial Gauge (DG). Cement bags were utilized for loading test.These loads are accumulated evenly in six steps. The total tested load was 4.2 tons. The tested beams were located in the Sport City-Khartoum State. This work reveals that the reflector-less Total Station-Leica 1202 (RLTS) produces a very strong correlation and an acceptable accuracy that stands within the limits of its minimum decimalfraction of the metric units. Several tests were carried out to confirm the linearity of the deflections against the loads. These tests are very important since they convey the information about the elastic behavior of the tested beams. In this regards, both measuring techniques produce correlation factors and R2 values for the loads vs. thedeflections of more than 0.98. The deflection accuracy of the Total Station, in terms of root-mean-square-error (RMSE), for the three beams were:  0.30 mm,  0.36 mm, and  0.39 mm, respectively. This finding indicates that the Total Station can provide sub-millimeter accuracy with respect to the dial gauge. The maximum deflection was found in beam number 3, which amounts to 7.9 mm from the Total Station and 7.85 mm from the dial gauge. Both measurement techniques produce recovery percentages that were greater than 88%. The overall findings of this experiment indicates that this reflector-less Total Station can be used for on-site measurement of deflection and for awide range of deflection/deformation measurement applications.

3-D modelling and visualization of large building using photogrammetric approach

The progress in modern technologies such as precise lightweight cameras mounted on unmanned aerial vehicles (UAV) and the more user-friendly software in the photogrammetric field, allows for 3-D model construction of any structure or shape. Software now achieves in sequence the processes of matching, generating tie points, block bundle adjustment, and generating digital elevation models.The aim of this study is to make a virtual 3-D model of the college of engineering /University of Duhok. Kurdistan Region, Iraq. The data input is vertical and oblique imagery acquired by UAV, ground control points distributed on the surrounded ground, facades, and roof. Ground control points were measured by the GPS RTK system in addition to the reflectorless total station instrument. The data is processed mainly using Agisoft PhotoScan software as well as the Global Mapper and the ReCap software. The output is a 3-D model, digital elevation model, and orthomosaic.Geometric and visual inspections were carried out. Some imperfections appeared on the sharp edges and parapets of the building. In the geometric accuracy of selected points on the building, the maximum standard deviation in the coordinates was ±4cm. The relative accuracy in distance measurements were in the range of 0.72% to 4.92 %

Important methods measurements to exam the accuracy and reliability of reflector-less total station measurements

Inaccessible points are difficult to measure because the prism cannot be position in these points, so reflector-less total station has solved this problem and these points can be measured easily. But the vital question is, if these measurements are accurate and reliable. This research has carried out to identify the vital methods measurements that have to be done to identify the reliability and the exact accuracy of the reflector-less measurements. Results are not general for all total station types because each instrument has its own specifications, and the continues use of the instrument (old used instruments) could affect the accuracy of measurements. In the third world countries or in specific in our cities, old version surveying instruments are still used in most projects. In some projects specially in high accuracy projects (such as bridges monitoring by using total station), it is important to know the exact distance that errors are going to be introduced by using reflector less total station (the distance between the target and the instrument). By identifying the limitations, the errors can be avoided, and the required accuracy can be obtained. In this research many observations in different locations are carried out in two situations, the first one by using prism and the second one by using reflector-less mode to compare between them. This study has identified many aspects include: the effects of beam divergence and the incidence angle on the accuracy and reliability of the measurements. In addition, the limitation of the reflector-less technology when the high accuracy is required. Furthermore, it has suggested the solution to this problem. In this research methods measurements to exam the reliability and the exact accuracy of the reflector-less measurements have been identified for total station Topcon ES-103, and these methods could be used to any type of total station before start in any high accuracy project. When the reflector-less measurements limitations are identified, the errors could be avoided.

Technique of constructing a measuring base for determining the azimuthal attitude of the dynamic test-bench Actidyn “ST2356C”

Calibration of inertial sensors is one of the most important tasks in the development of inertial navigation systems. The solution to this problem is impossible without achieving the required level of accuracy of dynamic modeling test-benches used in their development. The paper describes a technique of constructing a measuring base for determining the azimuthal attitude of the precision dynamic test-bench. This techniques used industrial geodesy technologies for providing ability to calibrate all major types of modern inertial measuring units in a wide temperature range. The azimuthal attitude determining is based on measuring the angular attitude of the mirror placed on the test-bench’s turntable by an autocollimation measurements technique by using a high-precision reflectorless total station, the coordinates of which are determined by rangefinder-goniometric measurements to reflectors with known coordinates, mounted on the room’s walls. The calculation results shows that proposed technique of constructing a measuring base allows to ensure the measurement accuracy for carrying out research and calibration of highly accuracy inertial measuring systems.

A new Approach for surveying the axis of cylindrical pipes using a reflectorless total station

Abstract To survey the pipe’s axis used in the installation of the cable-stayed bridge, a reflectorless total station and a proposed surveying observation technique were used. The approach includes a new method for observation and a graphical solution for the pipe’s axis determination. The technique shown in this paper can be applied for vertical and semi-vertical cylindrical pipes. A field test with real data and results is also presented.

Surrounding Factors’ Influence on the Accuracy of the Digital Level and Total Station

The digital level (SOKKIA SDL-30) and total station (SOKKIA CX-105) are highlighted as examples of digital surveying instruments. In this study, it is clarified how some surrounding factors can affect their efficiency such as vibration, sunlight, and its direction, temperature, and battery capacity. Through vibration testing as one of these factors ,both the digital level and the total station using the reflector-less were exposed to vibration up to 25 KHZ/Sec, the average and the standard deviations elevation error for the digital level increased by 2 times at 80 m distance , and the average and the standard deviations positioning error increased 3 times for the total station using the reflector-less total at 80 m distance between the instrument and bar code. 64.3% and 51.25% are the increasing ratios in average error for digital level and total station with reflector-less prism by testing the effect of sunlight and its position. The increase in temperature leads to an increase in the average error with 150 % and 66.6% for digital level and reflectorless total station. Finally, the lack of battery efficiency led to a shortage of accuracy of the Surveying Instruments.

Finite Element Application in Reservoir Deformation Analysis (Pilot Phase 2)

Finite element method (FEM) is a numerical technique for solving Engineering problem and Mathematical Physics. Useful problems with complicated geometries, Loading, and material properties where analytical solutions may not be obtained. Some of the complicated problems involving load is a cylindrical Reservoir structures where crude oil is stored in a Tank Farm. This paper demonstrates the use of Finite Element Analysis in above surface cylindrical Reservoir Engineering Structure. The reservoir which has sixteen (16) monitoring station was monitored using reflectorless Total station. This paper is the second phase of our pilot model and we hope to developed this second phase further to cover nine studs. The studs covered ranges from northern part of the Reservoir to the southern parts to further test the application of FEM triangular shaded (Truss) elements.

Precision Comparison and Analysis of Reflector-less Total Station Observations

In order to achieve the results that meet the specifications of given project, such as setting out and monitoring the structural deformation, the knowledge of reliability and accuracy of surveying equipment is inevitable. Reflector-less total station are widely used nowadays for several applications in geodetic engineering due to its highly accurate and fast measurements. A shortcoming is that it gives less accurate measurements in some cases of observations. The point position determination using reflector-less total station is subjected to some uncertainty due to angle of observation, incidence angle of signal to the surface, distance from the instrument to the point, instrument precision and material of reflecting surfaces. This paper investigates the accuracy of reflector-less total station observations during the process of monitoring and setting out of engineering structures. This paper is performed also to find out the effect of inclined angle of reflecting surface, its color and type on the accuracy of reflector- less total station measurements. It has been converted to a group of charts that assure the accuracy required in determining the point coordinates. A formula is developed to represent the effect of these parameters on the uncertainty of the observations. The results of the practical measurements, adjustment and analysis of the observations are also presented. From the results, It can be concluded that the white reflector surface have stronger reflectivity than any other surface. The unpainted metal target was the worst reflecting surface and the brick target was the best surface.

Efficient three-dimensional field documentation methods for labour cost studies: Case studies from archaeological and heritage contexts

The aim of this paper is to present alternatives for three-dimensional field documentation methods which can be used to record architectural features for econometric labour cost studies. Combining reflectorless total station line-drawing with photogrammetry produces high-quality three-dimensional models of the targets which can subsequently be analysed to derive volumetric data of the employed building materials and the sizes of the individual elements. The case studies compare how different variations and combinations of three-dimensional architectural documentation can be used to create sufficiently accurate models for architectural energetics studies with varying degrees of time and expense in the field and in the post-processing phase of the research. The documentation method has been developed by the first author of this paper and disseminated through annual fieldschools conducted on archaeological sites. The standard documentation procedure is to establish ground control points and an alternative based on inbuilt instrument GPS systems is also discussed.

Automation of data processing processes

The article describes the process of automated data processing. The examples of actual programs that are in demand for geodetic data applicable in the construction industry. In an experimental part of the paper provides a comparison of models reflectorless total station (BET), automating.

Determination of the under water position of objects by reflectorless total stations

When surveying through a water surface, a distortion of several centimetres caused by the refraction and the change in the velocity of the electromagnetic waves can be observed. Therefore, neither the position nor the height of an underwater point (object), which can be seen from above the water surface, is correctly measured. The authors want to point out the magnitude of geometric errors when measuring to points under water as well as the computation of correct under water positions of points from measurement through a water layer. A practical experiment was performed for a water depth of 0.16 m.

Comparison of Different Measurement Techniques as Methodology for Surveying and Monitoring Stainless Steel Chimneys

The measurement of a chimney axis is an engineering geodesy task. These measurements allow to assess the technical condition of chimneys and are usually carried out for reinforced concrete chimneys. When measuring high chimneys, the main problem may be the need to go a long distance to take a measurement. The surface of the chimney can also be problematic because it can absorb so much light from the range finder that total station reflectorless measurement or laser scanning will not be possible or will be affected by significant error. Chimneys made of stainless steel are also used today. They are not as high as reinforced concrete chimneys, but measuring them using reflectorless total stations or laser scanning can also be problematic. Problems arise from the reflective surface of these chimneys. The article presents a comparison of measurement results of a stainless steel chimney fragment obtained from total station measurement and laser scanning. Similarities and differences in the obtained axis of this chimney fragment are presented.

Finite Element Application in Reservoir Deformation analysis (Part 1)

Finite element method (FEM) is a numerical technique for solving engineering problem and mathematical physics, useful problems with complicated geometries, loading, and material properties where analytical solutions may not be obtained. Some of the complicated problems involving load is a cylindrical reservoir structure where crude oil is stored in a tank farm. This paper demonstrates the use of Finite Element Analysis in above surface cylindrical reservoir engineering structure. The reservoir which has sixteen (16) monitoring station was monitored using reflectorless Total station. This paper is a pilot model and it is hoped to be developed further in two more phases to cover the entire reservoir under study. Only two studs in the North East and South East directions were selected to test the FEM forming a triangular shade (Truss) with three elements. The 2-D horizontal displacement was found to be 0.02 mm, while the vertical displacement was found to be -0.03 mm.

Modelling the Surface of Racing Vessel’s Hull by Laser Scanning and Digital Photogrammetry

The knowledge of the hull shape and geometry of a racing vessel is one of the most important factors for predicting boat performance. The Offshore Racing Congress (ORC) rating system specifies the calculation parameters of the hydrodynamic forces of boat lift and drag on the basis of input data as the length of waterline while sailing, displacement, wetted surface and the volume distribution along the hull. It is represented by sophisticated calculations for national as well as international events and races. Measurement using a reflectorless total station in a coordinate system defined by the sailboat hull is the most established method approved by the ORC organisation. The determination of these geometric parameters by new, unconventional technologies, which should provide a quicker and more detailed measurement while preserving the quality and accuracy of results necessary for the handicap calculations was our main objective. Geometrical shapes of a cabin sailboat hull were determined by the technology of terrestrial laser scanning and two methods of digital close-range photogrammetry—convergence case of photogrammetry and Structure-from-Motion (SfM) method. High-Definition Surveying (HDS) targets for laser scanning and coded targets for digital photogrammetry were used throughout all methods in order to transform the resulting data into a single local coordinate system. The resulting models were mutually compared by visual, geometrical and statistical comparison. In conclusion, both technologies were considered suitable, however, with various advantages and disadvantages. Nevertheless, although labour intensive, the SfM photogrammetry can be considered the most suitable method if the correct procedures are followed.

The Impact of Vibration on the Accuracy of Digital Surveying Instruments

A digital surveying instrument has a crucial and effective role in civil engineering. These digital surveying instruments have contributed to providing quick and simplified solutions to solve many surveying problems: particularly accuracy, saving time, and effort .Therefore, the main objective of this research is the study of the vibrations effect on digital devices efficiency during the observation process, which occur frequently especially when the devices occupy the bridges during observation or when the occupation of the device is set nearby the railways, as well as in construction sites with heavy equipment movement. Although most digital surveying instruments contain a compensator device, this research find out through the experimental test that the effect of vibration on the accuracy of observation results and the noticed errors may extend to many centimeters. In case of using the digital level devices (SOKKIA SDL-30) under exposure to vibration (up to 20 KHZ/Sec), the average error of elevation was 36.9 mm in 80 m distance and the maximum standard deviation elevation error was 18.26 mm. But in the case of using the reflector-less total station (SOKKIA SET330RK) under exposure to vibration (from 7.5 to 15 KHZ/Sec), the average error of positioning was 79.95 mm in 85 m distance and the maximum standard deviation positioning error was 43.41 mm.

Measurement point density and measurement methods in determining the geometric imperfections of shell surfaces

Abstract In geodetic measurements of deformations in shell cooling towers, an important factor is to optimize the number of points representing the exterior surface of the shell. The conducted analyses of damage to such structures proved that cooling towers exhibited shell deformation consisting of irregular vertical waves (three concavities and two convexities), as well as seven horizontal waves. On this basis, it is claimed that, in accordance with the Shannon theorem, the correct representation of the generated waves requires the measurement of the cooling tower shell in a minimum of 12 vertical and 14 horizontal sections. Such density of the points may not be sufficient to represent local imperfections of the shell. The article presents the results of test measurements and their analysis, which were conducted to verify the assumptions as to the optimal number of measurement points for the shell of a cooling tower. The evaluation was based on a comparative analysis of the data obtained by the Terrestrial Laser Scanning (TLS) method, creating a very detailed model of geometric imperfections in an actual cooling tower with a height of 100 m. Based on the data obtained by the TLS method, point grids of various density were generated. An additional measurement of the cooling tower shell deformation was performed using a precise electronic total station with reflectorless measurement option. Therefore, it was possible to assess the accuracy of measurements by laser scanning in relation to measurements obtained by reflectorless total stations.

Suitability of structure from motion for rock‐slope assessment

AbstractThis study examines three sites in Alaska with unstable rock slopes that were surveyed using both terrestrial laser scanning (TLS) and structure‐from‐motion (SfM) techniques. The datasets were acquired simultaneously and linked to a rigorous survey control network. An accuracy evaluation of the SfM‐derived surface models was performed using the TLS data and numerous reflectorless total station observations collected across the rock slopes. A quality evaluation was conducted to examine differences in point density, model completeness and distributions of morphological properties between the SfM and TLS datasets. The results indicate that SfM is a viable option for unstable rock‐slope assessment when a sufficient number of images with adequate overlap are acquired and the reconstruction is tied to a survey control network. The best results, in terms of accuracy and completeness, were achieved when combining both unmanned aerial vehicle (UAV) and terrestrial imagery for the SfM reconstruction. However, issues such as over‐smoothing and geometric inconsistencies bring into question the suitability of SfM for the detection of small changes over time.

An investigation into the Accuracy of Distance Measurements to an object with the Pulse (Non-Prism) Total Station

In order to achieve the results that meet the specifications of a given project, like engineering surveys (e. g., Surveying of Buildings) , the knowledge of the reliability and accuracy of the surveying equipment is inevitable. The reflectorless total stations are used nowadays for several applications in civil engineering work due to their highly accurate , easy and fast measurements in an automated measuring process. The present paper investigates the accuracy and limits for prismless instrument Total Station especially in relation to observations with large (horizontal and/or vertical) angle of incidence to the reflecting surface , its colours and types, and beam divergence of the measuring signal. This study has been carried out with various surveying field tests by prism and prismless modes, using the pulse (non-prism) TOPCON GPT-2006 Total Station to evaluate the limitations and accuracy of this instrument in surveying the buildings (distance measurements).
 The current study has confirmed that while observations at right angles to an object ( building) are generally well within manufacturer specifications (σ=±10 mm), observations to surfaces of a building from a position that is not at right angles to the surface of the building ( signal beam) can introduce errors.
 Also , this study suggests that the angle of incidence of the measuring signal to the building points ( external and internal corners and wall surface points) has a large influence on the accuracy of that measurement. It is recommended to use horizontal angle of incidence for measuring the detail survey points between (-36 to + 36) degrees from the normal. Also, in case of measurements to a vertical surface, the maximum measured vertical angles of incidence was about forty degrees when using prismatic observations and fifty degrees for reflector less measurements. Some surveying techniques and recommendations are suggested to overcome these problems. Moreover, a good understanding of the non-prism instrument is required to get the required accuracy of the project. When using other total station equipment, the results of the current study can be used as a general guide only. The results of the current practical field experiments, computations and analysis of these tests using various calculations and least squares theory and computer programs (Excel and AutoCAD 2010) are also presented in digital and/or graphical forms.

A DEM of the 2010 surface topography of Storglaciären, Sweden

ABSTRACTDuring the summer of 2010 the surface elevation of Storglaciären in northern Sweden was measured using high-precision GNSS and reflectorless Total Station surveys. The DEM created from these data contain less noise than those created from orthophotographic methods over snow covered glaciers and is therefore smoother, with fewer erroneous features in the data. The principal, though not sole, intended use for the DEM is in the calculation of surface mass balance, which has influenced decisions on what constitutes a functional part of a glacier, leading to the exclusion of features such as snow aprons and perennial ice above the bergschrund. Other peripheral features have changed since the previous, aerial survey from 1999 leading to a reduction in size of approximately 0.17 km2.