1,363 research outputs found

    Photogrammetry in Traffic Accident Reconstruction

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    The aim of this research is to utilize PhotoModeler, a closerange photogrammetry software package, in various traffic accident reconstruction applications. More specifically, three distinct studies were conducted: 1.) vehicle crush measurement, 2.) road curve measurement, and 3.) an evaluation of common traffic accident reconstruction measurement methodologies. The first study applied the photogrammetric process to controlled crash information generated by the National Highway Traffic Safety Administration (NHTSA). A statistical procedure known as bootstrapping was utilized to generate distributions from which the variability was examined. The “within” subject analysis showed that 44.8% of the variability is due to the technique itself and the “between” subjects analysis demonstrated that 55.2% of the variability is attributable to vehicle type—roughly half and half. Additionally, a 95% CI for the “within” analysis revealed that the mean difference (between this study and NHTSA) fell between -2.52 mph and +2.74 mph; the “between” analysis showed a mean difference between -3.26 and +2.41 mph. The second study focused on photogrammetry in road curve measurement. More particularly, this study applied photogrammetry to (simulated) road curves in lieu of traditional measurement methods, such as measuring tapes and measuring wheels. In this work, thirty (30) different radii of curvature of various known sizes were deliberately constructed. Then photogrammetry was used to measure each of the constructed curves. A comparison of the known “R’s” (control group) and photogrammetry’s value of “R” (treatment group) was then made. Matched Pairs or Paired Comparisons were then used to examine these two populations. The difference between the photogrammetry “R” and the known “R” range is between 0.001% and 0.874%. Additionally, we are 95% confident that the mean difference of the two techniques is between -0.33 and 0.51 feet. Since this interval contains zero, we can conclude that the two techniques do not differ

    A Method for Automatic Image Rectification and Stitching for Vehicle Yaw Marks Trajectory Estimation

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    The aim of this study has been to propose a new method for automatic rectification and stitching of the images taken on the accident site. The proposed method does not require any measurements to be performed on the accident site and thus it is frsjebalaee of measurement errors. The experimental investigation was performed in order to compare the vehicle trajectory estimation according to the yaw marks in the stitched image and the trajectory, reconstructed using the GPS data. The overall mean error of the trajectory reconstruction, produced by the method proposed in this paper was 0.086 m. It was only 0.18% comparing to the whole trajectory length.</p

    FORENSIC ENGINEERING SURVEYS WITH UAV PHOTOGRAMMETRY AND LASER SCANNING TECHNIQUES

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    This work aims at presenting the use of new technologies in the field of forensic engineering. In particular, the use of UAV photogrammetry and laser scanning is compared with the traditional methods of surveying an accident site. In this framework, surveys must be carried out promptly, executed in a short time and performed so that the greatest possible amount of information is collected with sufficient accuracy to avoid the possibility of neglecting details once that the scene is no longer preserved. The combination of modern surveying techniques such UAV photogrammetry and laser scanning can properly fulfill these requirements. An experimental test has been arranged and instruments, procedures, settings, practical limits and results have been evaluated and compared with respect to the usual way of performing the survey for forensic purposes. In particular, both qualitative and quantitative considerations are given, assessing the completeness of the reconstructed model, the statistical evaluation of the errors and the accuracy achieved

    A new approach to energy calculation of road accidents against fixed small section elements based on close-range Photogrammetry

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    This paper presents a new approach for energetic analyses of traffic accidents against fixed road elements using close-range photogrammetry. The main contributions of the developed approach are related to the quality of the 3D photogrammetric models, which enable objective and accurate energetic analyses through the in-house tool CRASHMAP. As a result, security forces can reconstruct the accident in a simple and comprehensive way without requiring spreadsheets or external tools, and thus avoid the subjectivity and imprecisions of the traditional protocol. The tool has already been validated, and is being used by the Local Police of Salamanca (Salamanca, Spain) for the resolution of numerous accidents. In this paper, a real accident of a car against a fixed metallic pole is analysed, and significant discrepancies are obtained between the new approach and the traditional protocol of data acquisition regarding collision speed and absorbed energ

    Automatic segmentation and reconstruction of traffic accident scenarios from mobile laser scanning data

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    Virtual reconstruction of historic sites, planning of restorations and attachments of new building parts, as well as forest inventory are few examples of fields that benefit from the application of 3D surveying data. Originally using 2D photo based documentation and manual distance measurements, the 3D information obtained from multi camera and laser scanning systems realizes a noticeable improvement regarding the surveying times and the amount of generated 3D information. The 3D data allows a detailed post processing and better visualization of all relevant spatial information. Yet, for the extraction of the required information from the raw scan data and for the generation of useable visual output, time-consuming, complex user-based data processing is still required, using the commercially available 3D software tools. In this context, the automatic object recognition from 3D point cloud and depth data has been discussed in many different works. The developed tools and methods however, usually only focus on a certain kind of object or the detection of learned invariant surface shapes. Although the resulting methods are applicable for certain practices of data segmentation, they are not necessarily suitable for arbitrary tasks due to the varying requirements of the different fields of research. This thesis presents a more widespread solution for automatic scene reconstruction from 3D point clouds, targeting street scenarios, specifically for the task of traffic accident scene analysis and documentation. The data, obtained by sampling the scene using a mobile scanning system is evaluated, segmented, and finally used to generate detailed 3D information of the scanned environment. To realize this aim, this work adapts and validates various existing approaches on laser scan segmentation regarding the application on accident relevant scene information, including road surfaces and markings, vehicles, walls, trees and other salient objects. The approaches are therefore evaluated regarding their suitability and limitations for the given tasks, as well as for possibilities concerning the combined application together with other procedures. The obtained knowledge is used for the development of new algorithms and procedures to allow a satisfying segmentation and reconstruction of the scene, corresponding to the available sampling densities and precisions. Besides the segmentation of the point cloud data, this thesis presents different visualization and reconstruction methods to achieve a wider range of possible applications of the developed system for data export and utilization in different third party software tools

    The determination of pre-impact speeds and accident scene information using PhotoModeler as a measurement tool

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    This thesis investigates the role of PhotoModeler, a photogrammetry technique, in traffic accident reconstruction. More specifically, important elements to the reconstructionist such as vehicle crush and accident scene details are measured with PhotoModeler. The extracted measurements are utilized further to establish pre-impact speeds and vehicle placement in terms of the centerline. To verify that PhotoModeler is a suitable measurement technique, its results are compared against NTSHA controlled crash data and a pre-measured accident scene. The data are convincing. NTSHA\u27s crash tests are performed at 35 mph and this study\u27s results came up with 36.88 mph, which is quite good. In the accident scene diagram, the average measurement deviation was 1.480 inches, which is also a good result. PhotoModeler is accurate as well as convenient for generating measurements when applied to traffic accident reconstruction situations

    Virtual anthropology? Reliability of three-dimensional photogrammetry as a forensic anthropology measurement and documentation technique

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    Establishing the identity of unknown remains is a vital role of forensic anthropology. While establishing identity is generally straightforward due to conventional methods of identification like DNA analysis, sometimes these methods are not applicable in the case of remains that are heavily skeletonized, severely decomposed or severely charred. In such instances, a forensic anthropologist will be called upon. The role of the forensic anthropologist is to aid in the identification of remains when conventional methods such as DNA and fingerprinting are not applicable. They may also be required to collaborate with other experts like forensic odontologists in order to attain a positive identification. A number of methods are available to the anthropologist that can aid in achieving identification: comparative radiography, nonimaged records, craniofacial superimposition, dental comparison and craniofacial reconstruction. All the methods except nonimaged records require imaging, either in two dimensions or three dimensions. Three-dimensional imaging is quickly becoming a vital tool for reconstruction, comparison, and analysis in forensic science. It has found applications in road accident reconstruction, facial reconstruction, comparison of patterned injuries to the injury-inflicting instruments, and anthropometry. The main three-dimensional imaging methods utilized in the forensic field are photogrammetry, laser scanning and radiological scanning (computed tomography (CT) and magnetic resonance imaging (MRI)), with forensic three-dimensional/computer aided design (3D/CAD)-supported photogrammetry being the method that is primarily used due to its low cost, rapid results, does not need expertise to operate, has no radiation risks and, above all, the record is permanent. Regardless of this, CT and MRI are more established methods and are widely used in a variety of industries. The purpose of this paper is to compare and contrast the three-dimensional imaging methods currently employed in forensic science on the basis of reliability, reproducibility, and accuracy; with an ultimate aim of validating photogrammetry as an analytical and documentation method of forensic science

    Automated road extraction from terrestrial based mobile laser scanning system using the GVF snake model

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    Accurate extraction and reconstruction of route corridor features from geospatial data is a prerequisite to effective management of road networks for engineering, safety and environmental applications. High quality road geometry and road side features can now be extracted from dense point cloud LiDAR data, recorded by modern day Mobile Mapping Systems. This valuable route network information is gaining the attention of road safety and maintenance engineers. Road points are needed to be correctly identified, classified and extracted from LiDAR data before reconstructing intrinsic road geometry and road-side infrastructure. In this paper, we present a method to automatically extract the road from terrestrial based mobile laser scanning system using the GVF (Gradient Vector Flow) snake model. A snake is an energy minimizing spline that moves towards the desired feature or object boundary under the influence of internal forces within the curve itself and external GVF forces derived typically from 2D imaging data by minimizing certain energy such as edges or high frequency information. In our novel method, we initialise the snake contours over point cloud data based on the trajectory information produced by the MMS navigation sub-system. The internal energy term provided to the snake contour is based on adjusting the intrinsic properties of the curve, such as elasticity and bending, whilst the GVF energy and constraint energy terms are derived from the LiDAR point cloud attributes. Our method primarily differs from the traditional snake models in initialisation and in deriving the energy terms from the 3D LiDAR data

    Road Infrastructure Safety Management. Proactive Safety Tools to Evaluate Potential Conditions of Risk

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    The identification of highly critical sections in a road network is possible by examining the network operation, with the goal of determining the risk factors and observe the critical issues, in order to better plan possible improvements. Therefore, this study proposes a method to evaluate the coherence of existing road layouts, through the analysis of the geometric characteristics, theoretical speeds and drivers operating speeds, under different environmental and flow conditions. The analysis focuses on the road network managed by ANAS SpA in the Veneto Region, for which the reconstruction of the road axes geometry, the curvature graph and the theoretical design speed profile have been obtained, according to the indications of the Italian Ministerial Decree 05/11/2001. The theoretical design speed profile has then been compared with the information relating to the road users' mobility, in terms of the 85th percentile speeds, obtained from the extraction and analysis of the Floating Car Data (FCD). The data were processed by reconstructing the continuous profile of operating speeds with a specific regression function known as "smoothing cubic spline". The comparison with the theoretical design speeds allows to observe whether the users assume a behavior close to or distant from what is expected, based on the technical and geometrical characteristics of the road layout. The proposed methodology can contribute to the implementation of a proactive road safety check, aimed at recognizing and assessing the potential risk conditions for road traffic, with particular attention to the point of view of the road user

    Imaging in forensic science: Five years on

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    The Journal of Forensic Radiology and Imaging was launched in 2013 with the aim to collate the literature and demonstrate high-quality case studies on image-based modalities across the forensic sciences. Largely, the focus of this journal has been on the transmissive aspect of forensic imaging, and therefore a significant number of high-quality case studies have been published focusing on computed tomography and magnetic resonance imaging. As a result, the ‘and imaging’ aspect is often neglected. Since 2013, technology has fundamentally evolved, and a number of new techniques have become accessible or have been demonstrated as particularly useful within many sub-disciplines of forensic science. These include active and passive surface scanning techniques, and the availability of three-dimensional printing. Therefore, this article discusses non-contact techniques, their applications, advantages, and considerations on the current state of play of imaging in forensic science
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