Digital reconstruction of fragmented tooth remains in forensic context

Forensic odontology majorly focuses on the identification of victims through the analyses of oral and para-oral structures.Exposure to high temperatures and trauma can occur in mass disasters and may lead to the fracturing and fragmentation of teeth.These fragments may become very fragile and easily damaged while handling.Conventional methodologies such as the use of transparent nail polish,hair spray,cyanoacrylate or adhesives have been used to stabilise the fragmented pieces.This study introduces a new and innovative digital technique that utilises three-dimensional surface scanning(3DSS)and rapid prototyping techniques to reconstruct fractured portions of the teeth.The results of qualitative congruency analysis suggest that over all variance of morphological error(0.0526±0.05)mm.These results imply that the reconstructed 3D model can be used for various morphometric analyses.     

Latent Fingerprint Visualization using a Scanning Kelvin Probe in Conjunction with Vacuum Metal Deposition

The application of vacuum metal deposition before scanning Kelvin probe visualization of fingerprints is investigated. The potential contrast between fingerprint ridges and furrows is maximized by the use of silver deposition for non‐noble metals and gold–zinc deposition for noble metals. The higher susceptibility of eccrine fingerprints to vacuum metal overdeposition is confirmed. Additionally, fingerprints are best developed individually and by building the metal deposition slowly to protect against overdevelopment and variation in the rate of metal condensation. The progress of the metal deposition can be monitored using the scanning Kelvin probe by reference to the change in potential and continuity of the new potential on the surface. The use of acetic acid solution for the recovery of overVMD‐developed samples is shown not to be useful. Applying the metal deposition has the additional prospect of increasing surface conductivity and homogeneity and both can aid fingerprint visualization using the scanning Kelvin probe.     

Identifying Diagonal Cutter Marks on Thin Wires Using 3D Imaging

We present work on matching 2‐mm‐thick wires using optical 3D imaging methods. Marks on such small surfaces are difficult to match using a comparison microscope as this 2D imaging method does not provide height data about the sample surface. Moreover, these 2D microscopy images may be affected by illumination. Hence, the reference and investigated sample should be present at the same time. We employed scanning white light interferometry and confocal microscopy to provide quantitative 3D profiles for reliable comparison of samples that are unavailable for simultaneous analysis. We show that 3D profiling offers a solution by allowing illumination‐independent sample comparison. We correctly identified 74 of 80 profiles using consecutive matching striae (CMS) criteria, and we were able to match samples based on profiles measured using different 3D imaging devices. The results suggest that the used methods allow matching cutter marks on thin wires, which has been difficult previously.     

体表损伤与瘢痕的三维测量方法应用评估

目的检验结构光三维扫描法和单相机摄影测量法这两种三维测量方法在法医学体表损伤与瘢痕测量中的准确性和可靠性。方法对比分析直尺法、结构光三维扫描法和单相机摄影测量法对86处尸体损伤的测量结果;对比分析结构光三维扫描法、单相机摄影测量法、Photoshop套索像素法、PDF阅读软件法对13处活体模拟块状瘢痕面积的测量结果,并记录所耗时间;以贴纸的已知规格信息作为标准值,比较直尺法、结构光三维扫描法和单相机摄影测量法的测量准确度,计算均方根误差(root mean square error,RMSE);对不同操作者和同一操作者前后3次测量结果的可重复性进行组内相关系数(intraclass correla⁃tion coefficient,ICC)一致性评价。结果两种三维测量方法与直尺法在尸体损伤上测得的结果差异无统计学意义;结构光三维扫描法、单相机摄影测量法、PDF阅读软件法的测量结果和Photoshop套索像素法相比差异无统计学意义,单相机摄影测量法后处理耗时长于其他方法;直尺法测量长距离组(10~40cm)时结果小于标准值,RMSE值结果为结构光三维扫描法<单相机摄影测量法<直尺法;组内和组间的ICC值均大于0.99。结论结构光三维扫描法和单相机摄影测量法均可应用于法医学体表损伤的记录和测量,前者在测量精度及稳定性上表现更优,后者的数据色彩还原度更好,但后处理耗时较长。     

10例青光眼法医临床学鉴定分析

目的探讨青光眼的形成机制、鉴别诊断、鉴定方法等相关问题。方法对10例青光眼的临床法医学鉴定例资料进行回顾性研究。结果10例青光眼中,5例为外伤性青光眼,1例可能为混合型,4例属病理性青光眼;鉴定时间在伤后3-12个月,其中轻微伤2例,轻伤6例,重伤2例。结论外伤性继发性青光眼的认定首先需有明确的眼部外伤史,其次是有能导致青光眼的损伤,而后监测眼压确诊青光眼;与病理性青光眼主要鉴别点为前房深浅、前房角、杯/盘比(C/D)、眼底血管改变等;损伤程度应在明确诊断及进行相关治疗后,主要依据视力及视野损害情况确定。     

Suspect Height Estimation Using the Faro Focus3D Laser Scanner

At present, very little research has been devoted to investigating the ability of laser scanning technology to accurately measure height from surveillance video. The goal of this study was to test the accuracy of one particular laser scanner to estimate suspect height from video footage. The known heights of 10 individuals were measured using an anthropometer. The individuals were then recorded on video walking along a predetermined path in a simulated crime scene environment both with and without headwear. The difference between the known heights and the estimated heights obtained from the laser scanner software were compared using a one-way t-test. The height estimates obtained from the software were not significantly different from the known heights whether individuals were wearing headwear (p = 0.186) or not (p = 0.707). Thus, laser scanning is one technique that could potentially be used by investigators to determine suspect height from video footage.     

Three-Dimensional Integrated Survey for Building Investigations

The study shows the results of a survey aimed to represent a building collapse and the feasibility of the modellation as a support of structure analysis. An integrated survey using topographic, photogrammetric, and terrestrial laser techniques was carried out to obtain a three-dimensional (3D) model of the building, plans and prospects, and the particulars of the collapsed area. Authors acquired, by a photogrammetric survey, information about regular parties of the structure; while using laser scanner data they reconstructed a set of more interesting architectural details and areas with higher surface curvature. Specifically, the process of texture provided a detailed 3D structure of the areas under investigation. The analysis of the data acquired resulted to be very useful both in identifying the causes of the disaster and also in helping the reconstruction of the collapsed corner showing the contribution that the integrated surveys can give in preserving architectural and historic heritage.     

定量转印技术确定圆珠笔字迹的相对书写时间

定量转印技术是将单溶剂提取法与转印技术相结合形成的方法,实验表明该方法在一定条件下可以判定圆珠笔字迹的相对书写时间.     

Use of hand-held laser scanning in the assessment of craniometry

The intra- and inter-examiner reliability was evaluated for hand-held 3D laser scanning technology when it was combined with localization of landmarks for craniometry. The data from the laser surface scanning were compared with those of conventional direct measuring. Using thirty unidentified skulls requested for individual identification, measurements were taken of the line distances from lambda to 26 landmarks, and also for seven breadth parameters. For the laser surface scanning, two examiners performed replicate measurements with an interval of 1 week. In the conventional direct measuring, the first examiner took replicate measurements with a 1-week interval. To assess intra- and inter-examiner reliabilities, the intraclass correlation coefficient was used. Analysis of variance with repeated measures for each parameter was performed to compare the conventional method with the 3D scanning method. Both the 3D scanning and conventional methods showed excellent intra-examiner reliabilities, and the 3D laser scanning method also showed excellent inter-examiner reliability. A statistical difference between the two examiners was found only in nasal breadth in the 3D laser scanning method. There was no significant difference between the two measuring methods, though the 3D laser scanning method tended to give a slightly lower reading. Collectively, the 3D laser scanning method with point localization is a useful method with excellent reliability, and it can replace the conventional direct measuring method in craniometry.