Determination of Vehicle Speed from Recorded Video Using Reverse Projection Photogrammetry and File Metadata

The prevalence of security and in‐car video has increased the number of motor vehicle accidents captured on digital video. However, inconsistencies in how to accurately determine time and distance for vehicle speed has led to examinations with varying results. A potential solution for calculating time intervals is to use frame timing contained within many digital video file's metadata, recorded with 0.000001 sec precision. This paper examines a fatal motor vehicle accident where frame timing information was used with distance measurements from reverse projection photogrammetry to calculate vehicle speed. A margin of error was then calculated based on the accuracy in performing reverse projection photogrammetry distance measurements. The resulting speed calculation was then compared to event data recorder data and found to be within an average of ±1.43538 MPH. Using specific time intervals may lead investigators to more accurate speed calculations, specifically those involving variable frame rate video.     

道路交通事故法医检验技术的研究进展

近年来,经济快速发展和机动车数量急剧增多,道路交通事故频发和伤亡人数不断上升已经成为备受关注的全球性问题。法医检验作为交通事故处理中重要的证据,其鉴定意见直接影响着当事方的权益和事故处理。不容置疑,法医检验技术的运用对鉴定意见有十分重要的影响作用。本文对国内外法医检验技术的最新研究进展和应用进行综述,供同行实践工作中参考。     

Determination of average vehicle speed utilizing reverse projection

Reverse projection photogrammetry has long been used to estimate the height of an individual in forensic video examinations. A natural extrapolation would be to apply the same technique on a video to estimate the speed of an object by determining the distance traveled between two points over a set amount of time. To test this theory, five digital video recorders (DVRs) were connected to a single fixed camera to record a vehicle traveling down a track. The vehicle's speed was measured through Doppler radar by a trained operator and the speedometer of the vehicle was also recorded with a video camera. The recorded video was examined and the frames that best depict the beginning and end of the vehicles course were selected. Two reverse projection photogrammetric examinations were performed on the selected frames to establish the position of the vehicle. The distance between the two points was measured, and the time elapsed between the two points was examined. The outcome provided an accurate speed result with a standard degree of uncertainty. This study proves the feasibility of using video data and reverse projection photogrammetry to determine the speed of a vehicle with a limited set of variables. Further research is needed to determine how additional variables would impact the standard degree of uncertainty.     

稳态条件下EDR车速的可信度分析

目的分析稳态条件(例如,无制动)下国内车辆EDR碰前车速的可信度,为EDR碰前车速的应用提供参考。方法在国外研究结论的基础上,选取国内1起既有EDR数据又有监控视频的实际案例,利用监控视频计算所得车速为参考值,分析事故车辆稳态行驶时EDR车速的可信度,并结合EDR车速的来源对其进一步分析。结果根据国外文献研究结果可知,车辆稳态行驶时EDR车速的相对误差在±4%以内。通过国内1起实例的分析,显示稳态行驶车速为120 km/h,EDR记录的碰前车速相对误差为3.886%。结论结合EDR车速来源的分析表明,稳态条件下,国内车辆EDR记录的碰前车速同样具有很好的可信度,可有效应用到相关的车速重建中。     

Explosion Scene Forensic Image Interpretation

Image interpretation is an important aspect in the field of forensic science; however, it is seldom reported how to use these techniques in explosion scene forensic investigations. On 12 August 2015, a series of explosions killed 165 people and injured hundreds more at a container storage station at the Port of Tianjin. In this study, we applied image interpretation methods to determine the seat of the explosion by analyzing low‐quality video clips of the event. The interpretation fits well with recently published standard operating procedures, including the hypothesis, evaluation, inference, and confirmation. Image processing was adopted to enhance the images while the explosion scene was reconstructed with the same images. Some important features were extracted and utilized to distinguish whether the flashes were caused by reflection or a real blast. We reveal the real explosion location, which guides the overall investigation. The results indicate that image interpretation is a powerful tool for forensic investigators to analyze low‐quality images in complicated explosions or fire accidents.     

Simulation-based reconstruction of traffic incidents from moving vehicle mono-camera

Video recordings from digital cameras implemented in road vehicles present a valuable source of data concerning various dangerous traffic situations, i.e., road accidents or near-miss incidents. This data is readily available and numerous methods for forensic reconstruction of traffic situations from vehicle video were presented in the past. New alternative method for reconstruction of traffic situations from vehicle video is presented in this article. The method is based on the fusion of kinetic vehicle trajectory simulation within 3D laser scanner point cloud, projective geometry, and processing of video footage from moving vehicle camera. The method offers accurate reconstruction of general vehicle motion within relevant time domain whereby in-depth technical information about traffic incident can be quantitatively extracted from video footage. The result is physics-based 3D projection of simulated vehicle motion on the motion of real vehicle recorded by moving monocular camera. The method was validated within performed experimental test runs with respect to vehicle speed, distance travelled, acceleration/deceleration and directional quantities (yaw rate, yaw angle). The method was further applied in the reconstruction of real-world traffic events.     

道路交通事故中涉案者交通行为方式的法医学鉴定

目的回顾道路交通事故中需要进行涉案者交通方式鉴定的案例。探讨此类案例鉴定的思路和技术方法。方法收集28例近年本单位进行的道路交通事故涉案者交通行为方式鉴定案例,统计涉案者一般情况、损伤程度与交通行为方式的关系,交通事故发生的时间和地点、交通事故中车辆碰撞类型、采用的技术方法等,进行统计学处理。结果本组资料共28起道路交通事故案件,涉案人员共57人,男性50人．女性7人。交通事故发生时间夜间为19例（67．86％）,白天为9例（32．14％）。道路类型中,城市市区道路10例（35．7％）,城市郊区道路1例（3．6％）,省级道路10例（35．7％）,高速公路7例（25％）。酒后驾车9例（32．1％）。交通事故类型中,电动自行车与机动车事故5例（17．8％）,机动车与自行车事故1例（3．6％）,机动车单方事故7例（25．0％）;机动车与机动车事故11例（39．3％）,机动车与行人事故4例（14．3％）。涉案人员死亡27人,损伤29人,无明显伤害1人。损伤存活者中轻微伤10例（34．5％）,轻伤8例（27．6％）,重伤1l例（37．9％）。涉案者交通行为方式鉴定种类中,汽车驾驶人和乘车人认定16例（57．1％）,摩托车驾驶人和乘车人认定1例（3．6％）,电动自行车驾驶人和乘车人认定5例（17．8％）,自行车推行和骑行状态认定1例（3．6％）,摩托车推行和骑行状态认定1例（3．6％）,行人横过公路方向4例（14.3％）。涉案者交通行为方式鉴定采用的技术手段和方法．包括法医学活体损伤检验、法医学尸表检验、涉案肇事车车辆痕迹检验、DNA检验鉴定、现场人体模拟实验等。结论根据人体（活体或尸体）的体表损伤形态特征、痕迹分布,分析其致伤物和致伤方式,结合车辆痕迹检验结果,得出确认符合某种交通行为方式或者不符合某种交通行为方式的判断,结合案件的相关情况分析重建交通事故过程．是进行涉案者交通行为方式鉴定的基本思路。     

Evaluation of Computed Tomography as a Screening Test for Death Inquest

Abstract: The Japanese method of inquest, which depends mostly on external examinations, may misdiagnose a considerable number of accidental deaths and suicides as death by disease. We conducted computed tomography (CT) scans of 80 cases for which police concluded death by disease or natural causes based on police investigations into the circumstances and results from external examinations. The cause of death was clearly determined by CT scan in 17 of 80 cases. Ten cases underwent autopsy after the police suspected criminality based on results of the CT examinations. The results suggest CT scan may be a tool for preventing a number of overlooked crimes and accidents in Japan. However, it cannot be a perfect tool for discerning between death by disease and other causes of death without cooperation from the investigative agencies and subsequent forensic examinations such as autopsy and toxicological tests.     

计算机辅助法医教学系统

本研究综合应用多媒体计算机技术，结合法医学实际，研制出法医学尸体解剖教学的计算机软件．结果表明符合形象教学的要求．具有较强的交互能力，能按学习不同层次选择有关步骤和内容．     

车外人员撞击伤特点分析

目的以真实案例为基础,研究汽车碰撞事故中,不同机动车车型、不同交通方式等因素造成车外人员撞击伤的特征。方法选取上海地区发生的汽车与车外人员碰撞事故案例200例,通过对事故中的人、车等检验对比,分析车外人员撞击伤的特点。结果车外人员撞击伤主要出现在下肢,其次为胸部和头部;行人（含推车人）撞击伤出现频次与骑车人（含自行车或摩托车后座乘员）无明显差异;小轿车和小客车事故中撞击伤多见于下肢,大客车多见于胸部;车外人员被撞击后发生抛甩频率随车速的加大而增高,且通过车体痕迹检验,人体与车辆挡风玻璃发生（二次）撞击伤匹配程度最高。结论分析汽车与车外人员碰撞事故人体撞击伤特点,对于交通伤法医学鉴定及深化交通伤机制研究具有参考价值。     

多层螺旋CT在交通事故损伤生物力学分析中的应用

目的探讨多层螺旋CT(multi-slice computed tomography,MSCT)及三维重建技术在交通事故损伤生物力学分析方面的应用价值。方法以真实案例为基础,通过MSCT扫描获得尸体断层影像,进行三维图像重建,结合尸体解剖、车辆勘验等结果综合分析交通事故撞击、碾压和挤压等行为方式中的生物力学过程,并与尸体解剖结果进行对比。结果 MSCT和三维重建获得了不同受力部位骨折的位置、骨折线走向以及骨内碎裂状况等原位特征,其对于骨折的精细还原优于尸体解剖。结论 MSCT和三维重建技术在原位特征的再现、图像的易操作性以及证据的保全等方面凸显优势,可对道路交通事故损伤生物力学分析起补充和引导作用。     

基于视频的车速鉴定方法

视频监控设备的广泛应用为各类案件的侦破及取证提供了重要线索。利用高质量视频图像进行近景摄影测量、运动物体识别及跟踪的方法和技术已经较为成熟,但利用广角、低像素的视频监控录像定量描述车辆行驶速度的技术研究尚未开展。针对交通事故技术鉴定的实际需求,根据速度的一般计算方法和计算机视觉的基本原理,提出可以应用目前广泛使用的公共视频监控设备所拍摄的录像进行车辆速度计算的方法。     

老年人交通事故精神伤残鉴定的临床特征分析

目的探讨老年人交通事故受伤后精神伤残鉴定临床特征。方法对109例老年人发生交通事故受伤后精神伤残司法鉴定资料进行回顾性分析,并与非老年组进行对照研究。结果老年人多为被动性损伤、受伤后颅内血肿发生率高、致残的原因88．07％是智能及精神障碍所致,损伤程度及伤残等级以中、重度多见。结论最佳评残时机为脑外伤一年后为宜,应结合老年人的心理、生理特点,提高交通安全防范意识。     

CT‐Guided,Minimally Invasive,Postmortem Needle Biopsy Using the B‐Rob II Needle‐Positioning Robot

CT‐guided, minimally invasive needle biopsy techniques can be used to retrieve tissue or body fluid samples for histologic tissue diagnoses in forensic investigations. The purpose of this study was an evaluation of CT‐guided needle‐positioning robot B‐Rob II. To operate under CT guidance, we adopted the B‐Rob II robotic needle placement system and its workflow. The accuracy and speed of the procedure were tested on a gelatin phantom in a series of 21 biopsies. We achieved an average needle placement accuracy of 1.8 mm (±1.1 mm) using robotic assistance. The procedure required an average of 2 min 21 s. The needle placement accuracy for minimally invasive needle biopsies using the B‐Rob II biopsy robot is sufficiently accurate and fast for forensic postmortem examinations of focal organ changes. Further tests will be performed to test the feasibility of the robot for performing biopsies of focal organ changes in human bodies.     

基于3D激光扫描、多刚体重建和遗传算法优化的车-人碰撞事故再现模拟与损伤分析

目的利用3D激光扫描技术,结合多刚体动力学和遗传算法优化对一起汽车与自行车及其骑车人碰撞的交通事故进行再现模拟与损伤分析,为法医学死因鉴定提供生物力学依据。方法利用3D激光扫描技术对肇事汽车进行测量,根据测量数据建立人-自行车-汽车多刚体模型,并设置优化变量的取值范围,利用多目标遗传算法,带精英策略的快速非支配排序遗传算法求最优近似解,并与事故现场附近监控视频记录进行比较。结果事故车辆激光扫描重建结果良好,通过遗传算法优化收敛所获得的最优近似解中的假人、自行车、汽车的动力学行为与监控视频中所记录的三者动力学行为相符合,假人的损伤参数也与事故中骑车人的损伤情况及部位相一致。结论利用3D激光扫描技术,结合多刚体动力学和遗传算法优化可以对人-自行车-汽车碰撞前的运动状态、碰撞致伤过程进行重建,并对受害者的损伤进行力学分析,在交通事故受害人致伤方式鉴定及死因分析中具有应用价值。     

有限元方法在法医损伤鉴定中的应用

有限元方法（finite element method,FEM）是一种与现代计算机技术相联系的计算应力分析方法,已逐渐成为生物力学领域仿真人体结构力学功能研究的一个重要实验手段,可以有效地分析人体结构的物理性质,如受外力作用时人体组织的外部冲击响应及内部应力分布等,在法医损伤学研究及实践鉴定过程中具有较高的应用价值。文章综述了利用有限元方法分析高坠、交通及火器事故中颅脑损伤、脊柱损伤、骨盆损伤等的成伤机制、损伤生物力学等研究领域的成果,探讨其在法医损伤学研究以及法医检案中的应用价值。     

上海市城市轨道交通事故死亡案例分析

目的分析城市轨道交通事故死亡案例特点,为今后此类事故的法医学鉴定以及预防提供参考。方法收集上海市2005--2008年间城市轨道交通事故死亡案例18例,从案件的性质、损伤机制及特征等方面,总结此类案件的法医学特点。结果18例城市轨道交通事故死者,年龄在21～55岁。其中,自杀14例,意外4例;颅脑损伤死亡14例,创伤性休克死亡4例。损伤以撞击、摔跌伤为主,部分存在碾压伤。结论城市轨道交通事故所致损伤具有其特征性,案件性质主要为自杀,部分为偶然的意外事件,具有可防范性。     

交通事故中车辆安全技术状况检验及典型案例车速计算

目的 针对导致交通事故的各种原因就车辆因素进行了较详细的分析.方法 对进行车辆技术状况检验的着手方面、要点做了相关分析并结合相关实例进行举例分析,对造成事故中的关键因素车速的计算及计算方法做了简要讨论.结果 总结了进行整车配置、制动系统、转向系统、汽车灯光与信号系统与轮胎检验时需注意的要点.根据车速计算方法,得出一起追尾事故中某货车在事发时未达到高速公路最低限速的鉴定结论.结论 进行车辆安全技术状况检验时,需注意相关要点,以尽量避免道路交通事故的发生.     

再现技术在道路交通事故鉴定中的应用

事故再现是近年来交通安全领域研究的热点和难点,利用再现技术重建事故发生的碰撞瞬间及人体运动过程,对于法医分析交通伤致伤方式、损伤特点等具有重要价值。本文从我国道路交通事故鉴定的现状入手,通过对再现技术相关碰撞试验、假人模型和碰撞模型等的介绍,探讨事故再现技术在道路交通事故鉴定中的应用前景,进一步为事故责任认定服务。     

Failure of anthropometry as a facial identification technique using high-quality photographs

Anthropometry can be used in certain circumstances to facilitate comparison of a photograph of a suspect with that of the potential offender from surveillance footage. Experimental research was conducted to determine whether anthropometry has a place in forensic practice in confirming the identity of a suspect from a surveillance video. We examined an existing database of photographic lineups, where one video image was compared against 10 photographs, which has previously been used in psychological research. Target (1) and test (10) photos were of high quality, although taken with a different camera. The anthropometric landmarks of right and left ectocanthions, nasion, and stomion were chosen, and proportions and angle values between these landmarks were measured to compare target with test photos. Results indicate that these measurements failed to accurately identify targets. There was also no indication that any of the landmarks made a better comparison than another. It was concluded that, for these landmarks, this method does not generate the consistent results necessary for use as evidence in a court of law.