RETIME software for real time data acquisition using LEICA TCA series

Industrial survey is a discipline of engineering surveys that requires the utmost in achievable accuracies and real time data processing. The instrumentation used in conventional industrial survey requires long painstaking procedures with very skilled craftsmen to obtain the required results. Revolution of technology with the introduction of new instruments (such as total station, computer and software) has revolutionized industrial survey. The development of three dimensional (3D) coordinating system and total station interfaced to a microcomputer provides the capabilities for on line data gathering with simultaneous processing in 3D. This research concentrates on the development of software to acquire data from robotic total station (RTS) TCA2003 in real time. This software called RETIME is a short form of REal TIME. RETIME software consisted of the three core module i.e. (i) Data communication with RTS TCA2003, (ii) Calculate the raw data to produce 3D coordinates, and (iii) Convert the data from RETIME format into STAR*NET format. STAR*NET software (third party software) has been used in this research to provide an adjusted data. For verification purpose, RETIME software has been evaluated and the resulted are acceptable for industrial survey environment

Calibration and accuracy assessment of Leica ScanStation C10 terrestrial laser scanner

Requirement of high accuracy data in surveying applications has made calibration procedure a standard routine for all surveying instruments. This is due to the assumption that all observed data are impaired with errors. Thus, this routine is also applicable to terrestrial laser scanner (TLS) to make it available for surveying purposes. There are two calibration approaches: (1) component, and (2) system calibration. With the intention to specifically identify the errors and accuracy of the Leica ScanStation C10 scanner, this study investigates component calibration. Three components of calibration were performed to identify the constant, scale error, accuracy of angular measurement and the effect of angular resolution for distance measurement. The first calibration has been processed using closed least square solutions and has yielded the values of constant (1.2 mm) and scale error (1.000008879). Using variance ratio test (F-Test), angles observation (horizontal and vertical) for Leica C10 scanner and Leica TM5100A theodolite have shown significance difference. This is because the accuracy of both sensors are not similar and these differences are 0.01 and 0.0075º for horizontal and vertical measurements, respectively. Investigation on the resolution setting for Leica C10 scanner has highlighted the drawback of the tilt-and-turn target. Using the highest resolution, Leica Cyclone software only able to recognize the tilt-and-turn target up to 10 m distance compare to 200 m for the black and white target

Investigation of systematic errors for the hybrid and panoramic scanners

The existence of terrestrial laser scanners (TLSs) with capability to provide dense three-dimensional (3D) data in short period of time has made it widely used for the many purposes such as documentation, management and analysis. However, similar to other sensors, data obtained from TLSs also can be impaired by errors coming from different sources. Then, calibration routine is crucial for the TLSs to ensure the quality of the data. Through self-calibration, this study has performed system calibration for hybrid (Leica ScanStation C10) and panoramic (Faro Photon 120) scanner at the laboratory with dimensions 15.5m x 9m x 3m and more than hundred planar targets that were fairly distributed. Four most significant parameters are derived from well-known error sources of geodetic instruments as constant (a0), collimation axis (b0), trunnion axis (b1) and vertical circle index (c0) errors. Data obtained from seven scan-stations were processed, and statistical analysis (e.g. t-test) has shown significant errors for the calibrated scanners

Terrestrial laser scanners pre-processing: registration and georeferencing

Terrestrial laser scanner (TLS) is a non-contact sensor, optics-based instrument that collects three dimensional (3D) data of a defined region of an object surface automatically and in a systematic pattern with a high data collecting rate. This capability has made TLS widely applied for numerous 3D applications. With the ability to provide dense 3D data, TLS has improved the processing phase in constructing complete 3D model, which is much simpler and faster. Pre-processing is one of the phases involved, which consisted of registration and georeferencing procedures. Due to the many error sources occur in TLS measurement, thus, pre-processing can be considered as very crucial phase to identify any existence of errors and outliers. Any presence of errors in this phase can decrease the quality of TLS final product. With intention to discuss about this issue, this study has performed two experiments, which involved with data collection for land slide monitoring and 3D topography. By implementing both direct and indirect pre-processing method, the outcomes have indicated that TLS is suitable for applications which require centimetre level of accuracy

A study about terrestrial laser scanning for reconstruction of precast concrete to support QCLASSIC assessment

Nowadays, terrestrial laser scanning shows the potential to improve construction productivity by measuring the objects changes using real-time applications. This paper presents the process of implementation of an efficient framework for precast concrete using terrestrial laser scanning that enables contractors to acquire accurate data and support Quality Assessment System in Construction (QLASSIC). Leica Scanstation C10, black/white target, Autodesk Revit and Cyclone software were used in this study. The results were compared with the dimensional of based model precast concrete given by the company as a reference with the AutoDesk Revit model from the terrestrial laser scanning data and conventional method (measuring tape). To support QLASSIC, the tolerance dimensions of cast in-situ & precast elements is +10 mm /-5 mm. The results showed that the root mean square error for a Revit model is 2.972 mm while using measuring tape is 13.687 mm. The accuracy showed that terrestrial laser scanning has an advantage in construction jobs to support QLASSIC

Investigation of datum constraints effect in terrestrial laser scanner self-calibration

The ability to provide rapid and dense three-dimensional (3D) data have made many 3D applications easier. However, similar to other optical and electronic instruments, data from TLS can also be impaired with errors. Self-calibration is a method available to investigate those errors in TLS observations which has been adopted from photogrammetry technique. Though, the network configuration applied by both TLS and photogrammetry techniques are quite different. Thus, further investigation is required to verify whether the photogrammetry principal regarding datum constraints selection is applicable to TLS self-calibration. To ensure that the assessment is thoroughly done, the datum constraints analyses were carried out using three variant network configurations: 1) minimum number of scan stations, 2) minimum number of surfaces for targets distribution, and 3) minimum number of point targets. Via graphical and statistical, the analyses of datum constraints selection have indicated that the parameter correlations obtained are significantly similar

Practical accuracy of VRS RTK outside the Malaysian Real Time Kinematic Network (MyRTKnet)

Real Time Kinematic become a popular high precision technique in Malaysia. However, limitation of the distance for base station to rover station, this technique still difficult to implement. Virtual Reference Station (VRS) is a new concept developed by Trimble Terrasat is efficient method to overcome the limitation of classical RTK. The Malaysian Real-Time Kinematic Network (MyRTKnet) has been developed to facilitate RTK positioning in Malaysia. MyRTKnet consists 78 reference stations located at Peninsular Malaysia, Sabah and Sarawak. The most Northern reference station in Peninsular Malaysia located at Arau, Perlis. The gap distance from the Arau station to the Malaysia - Thailand border is around 35 km. This paper will discuss the practical accuracy of the RTK positioning using VRS generated by MyRTKnet outside the network. In this study, four points outside the MyRTKnet network were observed continuously in VRS RTK mode. Distances between rover station and the nearest physical reference station are 1 km, 10 km, 20 km and 30 km. It was found that the VRS generated using MyRTKnet can be achieved up to 6 cm in horizontal component and up to 8 m in vertical component even the positions of the rover stations are outside the MyRTKnet

Evaluating mobile laser scanning for landslide monitoring

Landslide is one of the natural disasters that give a huge impact to human life and social-economic development. Landslide needs to be monitored periodically in order to avoid loss of human life and damages of properties. Various methods have been used for monitoring landslide. This aim of the research is to evaluate the potential of mobile laser scanning technique for monitoring of landslide area. The objectives of the research are to acquire three-dimensional surface data of landslide area in different epochs and to analyze the movement of the landslide area using three-dimensional surface deviation and ground surveying techniques. The methodology begins with the GPS survey for the establishment of ground control points for the project area. The total station survey was then carried out to measure the three-dimensional coordinates of twenty well distributed targets located at the project area. The data collection phase was then continuing with the mobile laser scanning survey. The processing of the two epochs data acquired from both techniques was then carried out simultaneously and the methodology concluded with the output comparison analysis for the movement detection of the land slip. The finding shows that the mobile laser scanning provides fast and accurate data acquisition technique of the landslide surface. The surface deviation analysis of the two epochs laser scanning data was capable to detect the movement occurred in the project area. The results were successfully evaluated using the changes of the three-dimensional coordinates of the targets from the two epoch’s ground surveying data

Terrestrial laser scanners datum transformation: insignificant analysis of scale factor

Due to the measurement mechanism employed by terrestrial laser scanners (TLSs), the pre-processing procedure has become crucial procedure to orient all acquired data into global or ground coordinate system. Rather than utilising all seven-transformation parameters, most of TLS practitioners have neglected the scale factor. Taking into consideration the uncertainties in deriving range data, disregarding the scale factor in datum transformation computation could jeopardise the quality of pre-processed results. To rigorously examine this argument, two experiments have been designed by considering the element of multi distances and multi sensors. Utilising phase (i.e. Faro Focus 3D) and pulse-based (i.e. Leica ScanStation C10) scanners, both experiments were carried out with computation of seven (7) transformation parameters and scale factors were extracted for the assessment. With the aid of statistical analysis, the computed scale factors were mathematically differentiate to the ideal value (i.e. 1.000 or no scale effect). Under 95% confidence level, the null hypotheses for both experiments have indicate an agreement that scale factor can be neglected in datum transformation process for both types of terrestrial laser scanners

Pembangunan perisian bagi perolehan data cerapan dari robotic total station (LEICA TCA) secara masa hakiki

Industrial survey is one of a discipline in engineering survey that requires the highest accuracies and real time data processing. Consequently, this research concentrates on the development of a software that can receives data from robotic total station (RTS) TCA2003 in real time. This software is called RETIME (REal TIME) and was developed using Microsoft Visual Basic V6.0. RETIME software consists of the three core modules i.e. data communication with RTS TCA2003, calculation of raw data to produce 3D coordinates, and conversion of data from RETIME format into STAR*NET format. STAR*NET commercial software has been used in this research to provide adjusted data after observation is done. In this research, five comparison analyses were performed. The result from the first analysis shows the capability of RETIME to receive true data from RTS TCA2003 with the standard deviations of horizontal angle (0.753�), zenith (0.816�) and distance (sub mm) smaller than APSWin V1.42. Least square estimation (LSE) analysis was used in the second analysis to evaluate RETIME data observation. The use of standard deviation values, which are 1.5� for angle and 1.1mm for distance, resulted in LSE analysis passing chi square test with five percent (0.05) significance level. Results from calculation comparison with other programming languages in the third analysis shows Microsoft Visual Basic V6.0 is capable of doing calculation for this research. The fourth analysis which used APSWin V1.42 data observation as reference proved the ability of RETIME to identify target movement. For the fifth analysis, observations were done using RTS TCA1102 and TCA1103 which proved the ability of RETIME to receive data from all RTS TCA series. Results from the entire analyses show that RETIME is suitable for industrial survey purpose