Example Predicate Questions to Qualify 3D Scan Data for Use in Judicial Cases and Law Enforcement Investigations
Overview
Here are some example questions you may want to consider when presenting scan data as part of evidence or testimony in a judicial case or a police investigation. The answers to questions like these may help validate the authority, authenticity, and accuracy of any analysis or conclusions based on scan data that may apply to a case.
Scanner
Q. Has the FARO® Laser Scanner been tested in scientific settings and public safety settings?
A. Yes. FARO is the world’s most trusted source for 3D measurement technology. The company develops and markets computer-aided measurement and imaging devices and software. Technology from FARO permits high-precision 3D measurement, imaging and comparison of parts and compound structures within production and quality assurance processes. The devices are used for inspecting components and assemblies, production planning, documenting large volume spaces or structures in 3D, surveying and construction, as well as for investigation and reconstruction of accident sites or crime scenes. There are multiple articles available discussing the testing of FARO laser scanners in public safety.
Q. Is FARO data peer reviewed?
A. Yes. The FARO data and FARO Zone software have been peer reviewed and there are multiple validation studies that have been published. Some of those studies can be found on FARO Assist, under Documents.
Q. Is there a known error or accuracy produced by the FARO 3D Laser Scanner?
A. Each version of the Focus scanner has a known error rate. Please refer here to the Technical Specifications Sheet for your scanner model. Each project has a Registration Report which provides the error rate for those scans, as they relate to one another, in that project.
Q. Is there acceptance within the scientific community?
A. Yes. 3D laser scanning is accepted within the scientific community.
Q. Is this an accurate representation of what you witnessed or saw at the scene in question?
A. 3D laser scanning is much like photography. Once you have scanned, you have digitally preserved that scene. Even if you conduct ‘clean-up’ of your scan, i.e.., remove moving cars or people, they were not a part of your scene. It would be no different than taking a photograph of your scene, realizing there were people standing in the way, and re-taking the photo to remove them.
Case
Q. What examinations were done by you about this case?
A. After processing and registration of scans, did you do further analysis? Conduct measurements? Create a fly-thru video? Forensic analysis or diagramming in FARO Zone software?
Q. What were the results of this examination?
Q. Did you write a report regarding the results of this examination?
A. FARO Zone software creates reports of results when using Power Tools for crash and crime analysis.
Q. What did that examination entail?
A. Photographs, Notes, Video, Measurements
Measurement
Q. How did you obtain measurements?
A. There are two (2) primary ways to obtain measurements in SCENE software. The first is to simply click between two (2) points and complete the measurement. The second is to create points (objects) and measure between those points. The second is better for court as it creates ‘repeatable’ measurements. If you are using Zone software, your measurements can be taken using the point cloud snaps feature.
Q. What instrument was used to obtain these measurements?
A. What was the model of your scanner? Focus S70/150/350? Focus Premium? Freestyle 2?
Q. Is the instrument calibrated to international standards?
A. FARO is certified under ISO 17025:2017 as the in-house work pertains to calibration of devices. FARO Service Centers provide standardized device calibration. NIST traceable calibration certifies that the lab or manufacturer (FARO), is equipped and able to calibrate the equipment to NIST standards and that FARO products match NIST-maintained measurement standards
Q. When was the last time the instrument was calibrated?
A. Refer to the calibration certificate that came with your device. It is recommended to have your device serviced and re-calibrated every year.
Q. Do you maintain calibration certificates?
A. You should always keep record of all calibration certificates. A scene scanned today may not go to court for several years. You will want to be able to product the calibration certificate for the year in which the scene was scanned.
Q. What is the measurement error rate of the instrument?
A. This is dependent on the scanner you used. Please refer here to the FARO Knowledge Base hardware specification sheet for error rates.
Q. What is the measurement standard deviation of this specific project / case?
A. Refer to the project Registration Report from SCENE software. This can be saved as a .pdf.
Q. Have you or are you able to generate a report documenting the standard deviation?
A. Refer to the project Registration Report from SCENE software.
Q. Is the raw data obtained from the instrument maintained?
A. What are your policies and procedures for storing your raw scans files? These are the .fls from the Focus scanner and .sfm from the Freestyle 2.
Q. How is the raw data secured?
A. Where are you storing the raw scan files? Server? Cloud?
Q. What is your data security protocol?
A. See above.
Q. Was a 3D reconstruction generated from the measurement data?
A. Beyond scanning, did you do any further analysis or reconstruction of your scene?
Q. What software was used to generate the reconstruction?
A. FARO Zone is our forensic analysis and diagramming software for producing courtroom deliverables.
Q. What specific measurements were obtained from the raw data that aided your reconstruction of events?
A. This question is specific to the analysis conducted.
Q. Are your results reproducible?
A. Your results are always reproducible. Anyone can take the raw scan data and obtain the same results.
Q. What training do you have relating to this instrument?
A. Did you complete the FARO Laser Scanner Certification course? Additional training in FARO Zone software? Virtual workshops? Internal training?
Q. How many scenes have you used this instrument in?
A. It is important to keep a log of the times you use the scanner in the field. Often, it is the operator that is questioned moreso than the scanner and data.
Q. How many reconstructions have you done using this instrument?
Shooting Incident Reconstruction/Bloodstain Pattern Analysis/Momentum/Crush
Q. Were you able to conduct an analysis utilizing the 3D data?
Q. What software did you use to conduct the analysis?
Q. Are there any validation studies regarding utilizing the software analysis?
A. There are multiple validation studies on various tools within FARO Zone software.
Q. What were the results of that analysis?
Q. Are you able to produce a report specific to the analysis you conducted?
Q. Are the results of the analysis report able to be verified based on the scientific method?
Keywords:
accuracy, testimony, evidence, error range, accreditation, accredited, certification, certified, police investigation, courtroom evidence