A new measurement capability was created by combining photogrammetry and metrology techniques to accurately measure one half of the XV-15 Tilt Rotor Research Aircraft at the Smithsonian’s Udvar-Hazy museum. The challenges imposed by the fuselage and surrounding environment at Udvar-Hazy were overcome by careful application of photogrammetry and metrology techniques. Data analyses and processing included the use of multiple reverse engineering programs to accurately generate a complete 3-dimensional water-tight geometry of the aircraft and rotor blade. This paper describes the photogrammetry and metrology measurement systems, technology and hardware set-up, data analysis and processing methods, future work, and lessons learned. In addition, selected measurement results of the fuselage and rotor blade are presented.

Cummings, Haley, Dominguez, Michelle, Solis, Eduardo, Silva, Christopher, Bowman, Belen, Burek, Shirley

Analysis of Dashcam Video for Determination of Vehicle Speed

2020-01-08774/14/2020

Using dashcam video footage to extract reliable vehicle speed data can be challenging when the only available image stream comes from a camera whose optical parameters are unknown. One means of overcoming such difficulties uses visible landmarks and features within the video frame whose dimensions can be independently measured. While good results have been obtained by others using a Total Station or LiDAR to physically measure locations for such purposes, this approach could prove difficult if a site of interest is inaccessible (e.g. on a busy highway that cannot be shut down) or if relevent features of the target location have changed (e.g. due to construction or even restriping of lanes lines). As an alternative to direct scene measurement, it is proposed that measurement of features visible in overhead satellite images be used to dimension relevant features visible in the video. In this work, videos from individual dashcams and phone-based cameras were used to calculate average

Leifer, Jack, Marquez, Alvaro

Geospatial Accuracy of Small Unmanned Airborne System Data in the Coastal Environment

TBMG-343305/1/2019

The purpose of this study was to assess the ability of commonly available COTS software to produce geometrically accurate orthometric mosaics and terrain models from low-altitude UAS imagery.

Geospatial Accuracy of Small Unmanned Airborne System Data in the Coastal Environment

19AERP05_065/1/2019

Determining the performance of image processing software could lead to better data collection strategy. Army Engineer Research and Development Center, Alexandria, Virginia The purpose of this study was to assess the ability of commonly available COTS software to produce geometrically accurate orthometric mosaics and terrain models from low-altitude UAS imagery. The coastal zone is a dynamic environment that requires temporal monitoring from flexible remote sensing tools. Changing weather, winds, and tides introduce difficulties when attempting to use sensors that are constrained by schedule to include satellite overflight or aircraft with hard collection dates and times. However, these collection requirements are well suited for small unmanned airborne system (UAS) platforms that can be deployed and made operational with minimal notice. Additionally, the low collection altitude, combined with short focal length imagers (often integrated into these small UAS platforms) are capable of

The Placement of Digitized Objects in a Point Cloud as a Photogrammetric Technique

09-06-02-00078/8/2018

The frequency of video-capturing collision events from surveillance systems are increasing in reconstruction analyses. The video that has been provided to the investigator may not always include a clear perspective of the relevant area of interest. For example, surveillance video of an incident may have captured a pre- or post-incident perspective that, while failing to capture the precise moment when the pedestrian was struck by a vehicle, still contains valuable information that can be used to assist in reconstructing the incident. When surveillance video is received, a quick and efficient technique to place the subject object or objects into a three-dimensional environment with a known rate of error would add value to the investigation. In addition, once the objects have been placed into the three-dimensional environment, the investigator would then be able to observe the physical evidence and environment from any perspective, including viewing and measuring what cannot be seen in

Harrington, Shawn, Lebak, Gabriel

An Evaluation of Two Methodologies for Lens Distortion Removal when EXIF Data is Unavailable

2017-01-14223/28/2017

Photogrammetry and the accuracy of a photogrammetric solution is reliant on the quality of photographs and the accuracy of pixel location within the photographs. A photograph with lens distortion can create inaccuracies within a photogrammetric solution. Due to the curved nature of a camera’s lens(s), the light coming through the lens and onto the image sensor can have varying degrees of distortion. There are commercially available software titles that rely on a library of known cameras, lenses, and configurations for removing lens distortion. However, to use these software titles the camera manufacturer, model, lens and focal length must be known. This paper presents two methodologies for removing lens distortion when camera and lens specific information is not available. The first methodology uses linear objects within the photograph to determine the amount of lens distortion present. This method will be referred to as the straight-line method. The second methodology utilizes

Terpstra, Toby, Miller, Seth, Hashemian, Alireza

Determining Position and Speed through Pixel Tracking and 2D Coordinate Transformation in a 3D Environment

2016-01-14784/5/2016

This paper presents a methodology for determining the position and speed of objects such as vehicles, pedestrians, or cyclists that are visible in video footage captured with only one camera. Objects are tracked in the video footage based on the change in pixels that represent the object moving. Commercially available programs such as PFTracktm and Adobe After Effectstm contain automated pixel tracking features that record the position of the pixel, over time, two dimensionally using the video’s resolution as a Cartesian coordinate system. The coordinate data of the pixel over time can then be transformed to three dimensional data by ray tracing the pixel coordinates onto three dimensional geometry of the same scene that is visible in the video footage background. This paper explains the automated process of first tracking pixels in the video footage, and then remapping the 2D coordinates onto three dimensional geometry using previously published projection mapping and photogrammetry

Neale, William T., Hessel, David, Koch, Daniel

A Survey of Multi-View Photogrammetry Software for Documenting Vehicle Crush

2016-01-14754/5/2016

Video and photo based photogrammetry software has many applications in the accident reconstruction community including documentation of vehicles and scene evidence. Photogrammetry software has developed in its ease of use, cost, and effectiveness in determining three dimensional data points from two dimensional photographs. Contemporary photogrammetry software packages offer an automated solution capable of generating dense point clouds with millions of 3D data points from multiple images. While alternative modern documentation methods exist, including LiDAR technologies such as 3D scanning, which provide the ability to collect millions of highly accurate points in just a few minutes, the appeal of automated photogrammetry software as a tool for collecting dimensional data is the minimal equipment, equipment costs and ease of use. This paper evaluates the accuracy and capabilities of four automated photogrammetry based software programs to accurately create 3D point clouds, by

Terpstra, Toby, Voitel, Tilo, Hashemian, Alireza

Tensile Test for Polymer Plastics with Extreme Large Elongation Using Quad-Camera Digital Image Correlation

2016-01-04184/5/2016

Polymer plastics are widely used in automotive light weight design. Tensile tests are generally used to obtain material stress-strain curves. Due to the natural of the plastic materials, it could be elongated more than several hundred percent of its original length before breaking. Digital Image Correlation (DIC) Analysis is a precise, full field, optical measurement method. It has been accepted as a practical in-field testing method by the industry. However, with the traditional single-camera or dual-camera DIC system, it is nearly impossible to measure the extreme large strain. This paper introduces a unique experimental procedure for large elongation measurement. By utilization of quad-camera DIC system and data stitch technique, the strain history for plastic material under hundreds percent of elongation can be measured. With a quad-camera DIC system, the correlation was conducted between two adjacent cameras. These four camera DIC system could obtain much wider test range without

Xie, Xin, Zeng, Danielle, Li, Junrui, Dahl, Jeffrey, Zhao, Qiancheng, Yang, Lianxiang

The Accuracy of an Optimized, Practical Close-Range Photogrammetry Method for Vehicular Modeling

2016-01-14624/5/2016

Three targeted vehicles of varying size were measured using an optimized, practical photogrammetry technique and the results were compared to measurements acquired via total station. The photogrammetry method included the use of a field-calibrated DSLR camera equipped with a fixed 20 mm lens, retroreflective targets sized for vehicular modeling, and a CNC-machined scale bar. Eight photographs were taken from proper angles and processed using a commercially available photogrammetry package. This data was merged with the total station data using a cloud-to-cloud registration process for point-to-point comparison of positional data. The average residual between corresponding photogrammetry and total station points was 1.7 mm (N = 258, SD = 0.8 mm) with a 95% confidence limit of 3.1 mm. Considering this low residual, one of the sample vehicles was re-measured using a high accuracy FaroArm for comparison to the photogrammetry technique. The average residual between corresponding

Peck, Louis R., Cheng, Mu-Hua

Evaluation of the Second Transport Rotorcraft Airframe Crash Testbed (TRACT 2) Full Scale Crash Test

F-0071-2015-10138

5/5/2015

ABSTRACT Two Transport Rotorcraft Airframe Crash Testbed (TRACT) full-scale tests were performed at NASA Langley Research Center's Landing and Impact Research Facility in 2013 and 2014. Two CH-46E airframes were impacted at 33-ft/s forward and 25-ft/s vertical combined velocities onto soft soil, which represents a severe, but potentially survivable impact scenario. TRACT 1 provided a baseline set of responses, while TRACT 2 included retrofits with composite subfloors and other crash system improvements based on TRACT 1. For TRACT 2, a total of 18 unique experiments were conducted to evaluate ATD responses, seat and restraint performance, cargo restraint effectiveness, patient litter behavior, and activation of emergency locator transmitters and crash sensors. Combinations of Hybrid II, Hybrid III, and ES-2 Anthropomorphic Test Devices (ATDs) were placed in forward and side facing seats and occupant results were compared against injury criteria. The structural response of the airframe

Annett, Martin, Littell, Justin

Accuracy of SUAS Photogrammetry for Use in Accident Scene Diagramming

2015-01-14264/14/2015

Photogrammetry from images captured by terrestrial cameras and manned aircraft has been used for many years to model objects, create scale diagrams and measure distances for use in traffic accident investigation and reconstruction. Due to increasing capability and availability, Unmanned Aircraft Systems (UAS), including small UAS (SUAS), are becoming a valuable, cost effective tool for collecting aerial images for photogrammetric analysis. The metric accuracy of scale accident scene diagrams created from SUAS imagery has yet to be compared to conventional measurement methods, such as total station and laser measurement systems, which are widely used by public safety officials and private consultants. For this study, two different SUAS were used to collect aerial imagery for photogrammetric processing using PhotoModeler software. A high-resolution consumer grade camera as well as a lower-resolution integrated camera was used as payload to determine the effect of camera resolution on the

Jurkofsky, Drew A.

Improved Math Model for Multiphoto Measurement Systems

TBMG-20582

9/1/2014

The bundle adjustment, or more specifically, the colinearity math model it is based on, is undisputedly the most accurate method to perform 3D scene reconstruction from multiple images. It has been the gold standard since first developed in 1957–1959. The limitations of the method have motivated this investigation into how it could be improved.

Blade Displacement Predictions for the Full-Scale UH-60A Airloads Rotor

F-0070-2014-9446

5/20/2014

An unsteady Reynolds-Averaged Navier-Stokes solver for unstructured grids is loosely coupled to a rotorcraft comprehensive code and used to simulate two different test conditions from a wind-tunnel test of a full-scale UH-60A rotor. Performance data and sectional airloads from the simulation are compared with corresponding tunnel data to assess the level of fidelity of the aerodynamic aspects of the simulation. The focus then turns to a comparison of the blade displacements, both rigid (blade root) and elastic. Comparisons of computed root motions are made with data from three independent measurement systems. Finally, comparisons are made between computed elastic bending and elastic twist, and the corresponding measurements obtained from a photogrammetry system. Overall the correlation between computed and measured displacements was good, especially for the root pitch and lag motions and the elastic bending deformation. The correlation of root lead-lag motion and elastic twist

Biedron, Robert, Lee-Rausch, Elizabeth

Four-Point Planar Homography Algorithm for Rectification Photogrammetry: Development and Applications

2013-01-07804/8/2013

Photogrammetric techniques of analyzing vehicles and scenes for accident reconstruction are well documented and have appeared in various forms and levels of complexity over the years. Plane-to-plane rectification algorithms, frequently used for accident reconstruction, are subsets of a growing field of computer vision algorithms, which are rigorously developed in [1,2,3,4]. While these algorithms are well formulated, they are not well illustrated. It is often not clear how to leverage advancements in computer vision algorithms for the purposes of rectification photogrammetry in the context of accident reconstruction. Perhaps as expected, a second strategy exists in the literature, which describes the use, as opposed to the development, of commercial computer programs for rectification photogrammetry [5,6,7,8]. Commercial software applications provide a robust and wide array of photogrammetric analysis. However, their use does not promote learning or insight into the mathematics of

Hovey, Chad, Toglia, Angelo

Video Projection Mapping Photogrammetry through Video Tracking

2013-01-07884/8/2013

This paper examines a method for generating a scaled three-dimensional computer model of an accident scene from video footage. This method, which combines the previously published methods of video tracking and camera projection, includes automated mapping of physical evidence through rectification of each frame. Video Tracking is a photogrammetric technique for obtaining three-dimensional data from a scene using video and was described in a 2004 publication titled, “A Video Tracking Photogrammetry Technique to Survey Roadways for Accident Reconstruction” (SAE 2004-01-1221). That paper described a method for generating a three-dimensional computer model of a roadway by using video of a drive-through of an accident scene and processing this video footage through available video tracking software.1,2 The benefit of being able to drive through an accident scene to collect data lies in the speed of such a method, but also in safety, as some accident areas are too heavy with traffic

Neale, William T., Marr, James, Hessel, David

The Accuracy of Photo-Based Three-Dimensional Scanning for Collision Reconstruction Using 123D Catch

2013-01-07844/8/2013

An experiment was conducted to examine the validity of freely available photo-based 3D scanning software for generating accurate 3D geometry of a vehicle. Currently, 3D vehicle geometry is routinely captured using total station survey equipment, coordinate measuring machines (CMM), laser scanning, or traditional point-based photogrammetry. While these methods produce sufficiently accurate results for collision reconstruction, they have limitations that can affect practical implementation. For example, manual surveying with a total station, CMM or traditional photogrammetry are all limited to the production of coordinate data at discrete, pre-defined points. In addition, total stations, CMMs and laser scanning devices are also expensive and require a significant amount of time in the field with the vehicle. In contrast, photo-based 3D scanning allows a 3D mesh to be created of a vehicle simply from a series of photographs using a consumer-grade digital camera. In this experiment, a

Erickson, Mark S., Bauer, Jeremy J., Hayes, Wilson C.

Estimating Foreign-Object- Debris Density From Photogrammetry Data

TBMG-161444/1/2013

Within the first few seconds after launch of STS-124, debris traveling vertically near the vehicle was captured on two 16-mm film cameras surrounding the launch pad. One particular piece of debris caught the attention of engineers investigating the release of the flame trench fire bricks. The question to be answered was if the debris was a fire brick, and if it represented the first bricks that were ejected from the flame trench wall, or was the object one of the pieces of debris normally ejected from the vehicle during launch. If it was typical launch debris, such as SRB throat plug foam, why was it traveling vertically and parallel to the vehicle during launch, instead of following its normal trajectory, flying horizontally toward the north perimeter fence?

3D Visualization in Geospatial Analysis

TBMG-147059/1/2012

The past decade has seen an explosion of observations from airborne and satellite-based multiand hyperspectral sensors, as well as from synthetic-aperture radar and LiDAR. Distilling useful information from this wealth of raw data is the domain of geospatial analysis, the collection of analytical, statistical, and heuristic methods for extracting information from georeferenced data. This information is important in serving the needs of a diverse set of industries including environmental conservation, oil and gas exploration, defense and intelligence, agriculture, coastal monitoring, forestry, and mining.

A Close-Range Photogrammetric Solution Working with Zoomed Images from Digital Cameras

2012-01-06124/16/2012

Close-range photogrammetry (CRP) is traditionally based on a network captured with the camera lens at a fixed focal length. A zoom lens is not desirable without solving the intrinsic camera parameters for varying focal length and lens distortion. When using a zoom lens camera, multiple focal lengths can be used if the camera is calibrated for each varying focal length, but most consumer grade lenses are not designed to accurately return to (or stay at) mid-range focal lengths. Similarly, using close-range photogrammetric software systems to accurately recover three-dimensional (XYZ) data from Point and Shoot (PAS) digital cameras has been problematic when the images were not intended for CRP. PAS cameras are automatically refocused and easily zoomed so the focal length and lens distortion are typically unknown for CRP mensuration purposes. In such circumstances, traditional CRP analysis can be both laborious and difficult without the correct camera parameters. Previously a CRP network

DeChant, Lee, Kinney, John R.

Close-Range Photogrammetry with Laser Scan Point Clouds

2012-01-06074/16/2012

Close range photogrammetry involves the determination of spatial information about objects in photographs within 300 meters of the camera's focal plane. The application of close range photogrammetry to vehicular accident reconstruction has grown exponentially in the past two decades because of its obvious advantage: it offers a cost and time effective, nonintrusive means to document the three-dimensional data pertinent to an accident. Using high resolution digital images in conjunction with control points and constraints from three-dimensional survey data has proven to be an effective way to reconstruct vehicle damage and scene evidence when the physical inspections are not viable. Advances in land surveying technology have introduced High Definition Laser Scanning (HDS) - a process that results in vast data sets of millions of points, referred to as point clouds. Individual points can be colored based on a variety of criterion, including surface reflectivity spectrum or a photo

Callahan, Michael Andrew, LeBlanc, Beau, Vreeland, Regan, Bretting, Gerald

Photogrammetric Measurement Error Associated with Lens Distortion

2011-01-02864/12/2011

All camera lenses contain optical aberrations as a result of the design and manufacturing processes. Lens aberrations cause distortion of the resulting image captured on film or a sensor. This distortion is inherent in all lenses because of the shape required to project the image onto film or a sensor, the materials that make up the lens, and the configuration of lenses to achieve varying focal lengths and other photographic effects. The distortion associated with lenses can cause errors to be introduced when photogrammetric techniques are used to analyze photographs of accidents scenes to determine position, scale, length and other characteristics of evidence in a photograph. This paper evaluates how lens distortion can affect images, and how photogrammetrically measuring a distorted image can result in measurement errors. Lens distortion from a variety of cameras is analyzed, and the ultimate effect that this distortion has on the image is evaluated, with a discussion on the overall

Neale, William T., Hessel, David, Terpstra, Toby

Wavefront Correction for Large, Flexible Antenna Reflector

TBMG-79355/1/2010

A wavefront-correction system has been proposed as part of an outer-space radio communication system that would include a large, somewhat flexible main reflector antenna, a smaller subreflector antenna, and a small array feed at the focal plane of these two reflector antennas. Part of the wave-front-correction system would reside in the subreflector, which would be a planar patch-element reflectarray antenna in which the phase shifts of the patch antenna elements would be controlled via microelectromechanical systems (MEMS) radio-frequency (RF) switches. The system would include the following sensing-and-computing subsystems:

Measuring Positions of Objects Using Two or More Cameras

TBMG-28396/1/2008

An improved method of computing positions of objects from digitized images acquired by two or more cameras (see figure) has been developed for use in tracking debris shed by a spacecraft during and shortly after launch. The method is also readily adaptable to such applications as (1) tracking moving and possibly interacting objects in other settings in order to determine causes of accidents and (2) measuring positions of stationary objects, as in surveying. Images acquired by cameras fixed to the ground and/or cameras mounted on tracking telescopes can be used in this method.

Measuring Positions of Objects Using Two or More Cameras

TBMG-TB-0028395/27/2008

This method could determine the causes of accidents. An improved method of computing positions of objects from digitized images acquired by two or more cameras (see figure) has been developed for use in tracking debris shed by a spacecraft during and shortly after launch. The method is also readily adaptable to such applications as (1) tracking moving and possibly interacting objects in other settings in order to determine causes of accidents and (2) measuring positions of stationary objects, as in surveying. Images acquired by cameras fixed to the ground and/or cameras mounted on tracking telescopes can be used in this method.

Creating Geospatial Content with Photogrammetry Software

TBMG-134206/1/2007

Over the last decade, the unprecedented population growth rates throughout much of the world and the subsequent need for information to support and manage that growth has put more pressure than ever before on geographical information system (GIS) and production mapping professionals. Businesses and planners need more up-to-date information than ever before, so much so that photogrammetry production “factories” can work 24/7 and still find it a challenge to keep up with the increasing volume of work.

Generating CAHV and CAHVOR Images With Shadows in ROAMS

TBMG-18829/1/2006

Part of the Rover Analysis, Modeling and Simulation (ROAMS) software that synthesizes images of terrain has been augmented to make the images more realistic. [ROAMS was described in “Simulating Operation of a Planetary Rover” (NPO-30722), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 52. ROAMS simulates the operation of a robotic vehicle (rover) exploring terrain on a remote planet.] The images are needed for modeling responses of rover cameras that provide sensory inputs for machine-vision-based algorithms for controlling the motion of the rover. The augmented image-synthesizing part of the ROAMS software supports terrain geometry and texture specifiable by the user, CAHV and CAHVOR camera models, and more-realistic shadowing (see figure). (The letters in “CAHV” represent vectors in a standard photogrammetric model of a pinhole camera. Letters O and R in “CAHVOR” represent vectors used to model distortions.) A contemplated future version of ROAMS would support the CAHVORE

A Method for Improving the Accuracy of Standard Stereo Photogrammetry When Using Small Subtended Angles

2005-01-07514/11/2005

In stereo photogrammetry, the accuracy of calculating the location of a point in space, decreases as the angle between the two cameras decreases. For vehicle crash testing, the need for accurate 3D data conflicts with the need for flexible positioning of the cameras, to enable unobstructed views of the targets inside the vehicle throughout the impact event. This paper discusses a method for increasing the quantity and quality of film analysis data when small subtended angles are used. The method uses the 3D information developed through triangulation of two cameras as input to a single camera analysis.

Byers, Lynn C., Slon, Christopher M.

Quantitative Assessment of Cosmetic and Structural Quality in Automotive Outer Body Panels Using ARAMIS Stereo Photogrammetry System

2005-01-05884/11/2005

The methodology described enables high accuracy in the measurement of static and dynamic stiffness and dent resistance. Among the parameters being evaluated are: stiffness and dent resistance of the automotive outer body assembled panels – under both static and dynamic loading and the effect of the stiffening features in the panel shape, upon its deformation characteristics under dynamic excitation and dynamic wave propagation following slow projectile impact. This methodology will help part and process designers to correctly position and manufacture outer and inner body features like door handle embossment shape and location, feature lines, lamp and mirror embossments, hemming lines and side bar locations. Measurements are carried out using the stereo photogrammetry system ARAMIS – a fast and cost effective tool with a high accuracy of displacement measurement in both static and dynamic conditions. Measurements were performed in real time related to the phase of elastic wave generated

Sikorski, Andrzej, Grabovskyy, Vitaliy

A Video Tracking Photogrammetry Technique to Survey Roadways for Accident Reconstruction

2004-01-12213/8/2004

When reconstructing vehicle accidents, it is often important to record the accident scene roadway geometry. Survey techniques such as the plane surveying method1 and the coordinate and triangulation method2, have been the most widely used recording methods and are generally accepted in the industry. This paper proposes to introduce video tracking photogrammetry as a new tool in gathering accident scene and roadway data. The video tracking photogrammetry technique makes it possible to use accident scene video to record the accident scene geometry by incorporating photogrammetry principles. This paper will also report on the accuracy of the video tracking photogrammetry technique and discuss its strengths and limitations.

Neale, William T.C., Fenton, Steve, McFadden, Scott, Rose, Nathan A.

Optical Coordinate Measuring Techniques for the Determination and Visualization of 3D Displacements in Crash Investigations

2003-01-08913/3/2003

The measurement of 3D coordinates using optical techniques is well known for more than 50 years. Today, modern photogrammetric systems are based on handheld digital cameras and are used to identify the location of any circular marker or feature on the object's surface. The ease of use and the accurate and automated derivation of 3D coordinates from 2D digital images helped to establish a powerful tool for position control, assembly checks and reverse engineering. A new application is the analysis of real vehicle crashes. The location of hundreds of markers on the damaged vehicle can easily be determined in vehicle body position. These coordinates are being compared to the undeformed geometry and provide herby 3D information on any displacement. Using reverse engineering techniques, surfaces are created from the 3D points and thus a 3D model of the crashed vehicle is available for an easy visualization of the deformation.

Behring, Dirk, Thesing, Jan, Becker, Holger, Zobel, Robert

System for Measuring Three Tilts and Distance of an Object

TBMG-2963011/1/2001

An optoelectronic system discussed herein measures the state of alignment (SOA) of an object under test in four of its six degrees of freedom (DOFs). This system was originally intended for use in determining the SOA of an optical bench in a vacuum chamber. The basic design and mode of operation of this system are also applicable to similar measurement problems that arise in a variety of endeavors, including general alignment of optics, alignment of structures, studies of deformations of structures, geodetic surveying, photogrammetry, and construction. Heretofore, in order to obtain the alignment information provided by this system, it would have been necessary to use at least two expensive theodolites or else multiple expensive low-distortion camera heads aimed along different lines of sight. The present system contains simpler, less-expensive optics, and its basic design is amenable to tradeoffs among range, sensitivity, and configuration.

Human Cervical Motion Segment Flexibility and Facet Capsular Ligament Strain Under Combined Posterior Shear, Extension and Axial Compression

2000-01-SC1211/1/2000

The cervical facet capsular ligaments are thought to be an important anatomical site of whiplash injury, although the mechanism by which these structures may be injured during whiplash remains unclear. The purpose of this study was to quantify the intervertebral flexibility and maximum principal strain in the facet capsular ligament under combined shear, bending and compressive loads similar to those which occur during whiplash loading. Two motion segments (C3-4 and C5-6) from seven female donors (50 ± P 10 years) were exposed to quasi-static posterior shear loads of 135 N applied to the superior vertebra on four occasions while under compressive axial preloads of 0 N, 45 N, 197 N and 325 N. Vertebral body motions and the full Lagrangian strain field in the right facet capsular ligament were measured using stereophotogrammetry. After flexibility testing, the right facet joint of each motion segment was isolated and failed in posterior shear. Differences in the kinematic response of the

Siegmund, Gunter, Myers, Barry S.

An Evaluation of Rectified Bitmap 2D Photogrammetry with PC-Rect

9709522/24/1997

Without good-quality measurements taken at the time of an accident the analyst is faced with the need to extract measurement data from incident scene photographs. This paper discusses the history and development of the mathematical model for two-dimensional (2D) single exposure analytical photogrammetry, presents the software PC-Rect, and compares the analytical results obtained with PC-Rect to survey results. The sensitivity of the analytical results to the variation in such parameters as subject distance, camera height, digital photograph resolution, and bitmap density is discussed. The concept of using the directly rectified scanned photograph in the reconstruction task is introduced, and the utility of performing the dynamic simulation directly on the rectified photograph is discussed.

Cliff, William E., Maclnnis, Duane D., Switzer, David A.

Band Information Reconstruction from a Single Photo - A Superimposed Method

9608932/1/1996

To interpret the information on a 2-D image of a 3-D world in order to determine the displacement of the 3-D objects portrayed in the image, this study superimposes the 2-D image with another photo which is taken from the same site and includes some additional objects with well defined dimensions. In this synthetic image, those added objects serve as a datum; mathematical functions are then used to evaluate the true size of any object in the image. In the computerized photogrammetry method proposed in this study, other than the need for an additional photo with known-dimension poles in it and the required adjustment on the direction and distance of this photo to suit for the target one, there is no extra field measurement necessary, nor is any adjustment introduced in the computational process.

Wang, Ying-Wei, Ting, Kuo-Liang, Kuo, Yo-Chung

Digital Rectification of Reconstruction Photographs

9610492/1/1996

Computerized photogrammetry as it relates to accident reconstruction is well known and has been documented by a number of researchers. Planar photogrammetry algorithms have been demonstrated to be adequate for a large number of situations involved in reconstruction. These algorithms all transform individual points in the photographic image plane to a plane associated with the objects of interest. The points are then presented in either tabular and/or line drawing form. This paper presents a planar method of rectifying an entire photographic image to the horizontal plane, so that the resulting rectified image can be viewed from directly overhead or from any other perspective. The method has specific advantages in analyzing accident scene photos containing skid marks, gouges, and other evidence, without the inconvenience of perspective distortion. The method also dramatically increases the volume of data which can be conveniently analyzed. The stages of the process are discussed and

Pepe, Michael D., Grayson, Eric, McClary, Andrew

The Use of Photogrammetry and Video Films in the Evaluation of Passenger Compartment Measurement and Occupant-Vehicle Contacts

9502392/1/1995

The evaluation of new safety systems in cars is based not only of the accident severity and type, but also on the behaviour of the interior of the vehicle in terms of intrusion and other interior deformations. It is also essential that contact points can be found explaining injuries to occupants and also showing possible restraint use. It is however complicated to measure interior deformations, especially in three dimensions and with non-specialists going out to the crashed car. It is also complicated to find contact points for non-specialists not always knowing the injuries of the occupants at the time of the interior inspection of a crashed car. In this paper, methods for distant evaluation of crashed car interiors with photogrammetrical and video cameras allowing three dimensional measurements and the possibility to judge interior contacts. With such methods, data collection can be performed by non-specialists with a high quality of the analysis. The methods are presented with

Kullgren, A., Lie, A.

Photogrammetry and Accident Reconstruction: Experimental Results

9409253/1/1994

A controlled experiment involving road marks was conducted to compare various photogrammetry practices currently in use in the accident investigation community. The experimental controls and results are discussed for three variations of one 2-D scheme and for six 3-D photogrammetric schemes applied to a similar set of road marks and points. For measurements related to the most frequent issues in traffic accidents, all of the methods are capable of providing usable data. The experimental photographs and corresponding data represent a reference set for developing skills and for comparison with other photogrammetry schemes.

Tumbas, Nicholas S., Kinney, J. Rolly, Smith, Gregory C.

Adapting Three-Dimensional Animation Software for Photo grammetry Calculations

9309043/1/1993

A new method for computer-based photogrammetry in accident reconstruction is presented. CAD software is used to produce three-dimensional models of the site, vehicles, and other objects important in the incident. Objects of known configuration are incorporated into the scene model, and a perspective view is created that corresponds to the photograph. Then the objects of unknown position are added, and these are translated and rotated until they match the photograph. The result is a three-dimensional computer model of the site geometry, from which positional information may be extracted by examining the top, front, and side orthographic views.

Campbell, A. T., Friedrich, Richard L.

Accuracy of Three-Dimensional Photogrammetry as Established by Controlled Field Tests

9306623/1/1993

Photogrammetry is the science of obtaining spatial information from photographs given a set of key reference points. Vehicular accident reconstruction frequently requires using the photogrammetric process to obtain dimensions of such items as skid mark length, vehicle rest positions, or depth of vehicle crush. This paper briefly describes the generalized three-dimensional photogrammetric process. Findings are then presented which show the accuracy of this process when applied to simulated reconstruction situations involving skid marks and vehicle crush. Specifically, three sets of photographs of simulated skid marks and one of vehicle crush were analyzed photogrammetrically. The results were then compared to a blind set of survey data which was revealed only after the photogrammetry calculations had been completed. The comparison between the survey data and photogrammetry calculations are presented in graphical form.

Pepe, Michael D., Sobek, James S., Zimmerman, D. Allen

A Development of Statistical Human Back Contour Model for Backrest Comfort Evaluation

9301143/1/1993

First, this paper describes a measurement of the human back-backrest interface contours and a reduction procedure of the measured contours to reconstruct the statistical back contours of American 50 and 95-percentile male. Second, the paper illustrates the difference of the back contour between the statistical male drivers and SAE 3-D Manikin. Finally, the advantage of using the back contour model in experiment is given. The AM 50 back contour model was used as a loader to obtain the backrest pressure distribution and proved an excellent tool for backrest comfort evaluation.

Nakaya, Hirosuke, Okiyama, Hiroshi

Determination of Vehicle Crush from Two Photographs and the Use of 3D Displacement Vectors in Accident Reconstruction

910118

2/1/1991

Given two or more photos of an accident vehicle (non-stereo pairs such as police photos) an estimate of the deformation (crush) of the vehicle may be obtained by application of camera reverse-projection, using two or more cameras and an exemplar vehicle. A single camera technique familiar to accident scene investigators is modified for this application. The methodology is described within the context of an experiment comparing results obtained by camera reverse projection to actual measured crush. A method of displaying crush results known as “displacement vectors” is presented and examples are illustrated. The technique has been found useful for measurement of 3-dimensional crush. This paper describes the two-image camera reverse-projection method, for determining automotive, accident-caused crush; procedures for applying this method including insights from the authors practical experiences; and a case-study example where results obtained from this method were compared to actual crush

Woolley, Ronald L., White, Karen A., Asay, Alan F., Bready, Jon E.

Computer-Aided 3-D Surface Reconstruction During High Speed Crush Events

910320

2/1/1991

A system which can remotely measure detailed deformations of vehicle structures during crush events was developed. The system uses ordinary video or 16 mm high speed movie to capture the crush event. This information is digitized and analyzed using personal computers to perform photogrammetric manipulations which yield accurate surface geometries. The output is useful for comparison to computer simulations. This paper presents preliminary results regarding the accuracy of this system.

Karvelis, Albert V., Rogers, Michael W., Anderson, Carl E., Liubinskas, Aldis

A Case Comparison of Single-Image Photogrammetry Methods

8907372/1/1989

Analytical reverse projection is introduced and is shown to offer an improvement in applicability and accuracy over other techniques of single-image photogrammetry, including plane-to-plane transformation and camera reverse-projection methods. A comparison of the methods is made on the basis of a single case of reconstructing missing tire tracks on a roadway intersection. Advantages and disadvantages of each method are discussed. THIS PAPER REVIEWS non-graphical techniques used to make measurements of features imaged in a single photograph. Two formulations of the plane-to-plane transformation method are re viewed, the camera reverse-projection technique is presented, and a third technique, called the analytical reverse-projection method, is introduced. Following a review of the various methods, including an indication of their advantages and disadvantages, each method is applied to the problem of relocating a set of tire tracks in an intersection. The results of each method are

Smith, Gregory C., Allsop, Douglas “L”

Field Application of Photogrammetric Analysis Techniques: Applications of the FOTOGRAM Program

861418

11/1/1986

This paper describes how a photogrammetric analysis computer program entitled FOTOGRAM™ is used with a personal computer. The FOTOGRAM program was described in a paper entitled “Photogrammetric Analysis Using the Personal Computer” by Brelin, Cichowski, and Holcomo.(1)* The technique described herein utilizes field examples to show how skid mark data are extracted from photographs using manual as well as electronic digitization methods. The digitized photographic data are then converted with the FOTOGRAM computer program into ‘real-world’ data points that may be plotted on a collision scene schematic. Thus, the actual path of the vehicle during skidding and/or tire marking can be determined for use in reconstructing the accident.

Grimes, Wesley D., Culley, Charles H., Cromack, J. Robert

Photogrammetric Analysis Using the Personal Computer

86141610/1/1986

“FotoGram” is a two dimensional photogrammetry software package developed by General Motors Corporation. It generates a transformation matrix from the input reference data which best represents a given surface and “transforms” the selected points into a plan view. The general usage of the “FotoGram” software in accident reconstruction is presented along with various methods of reference point measurement and placement.

Brelin, Janet M., Cichowski, William G., Holcomb, Michael P.

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