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Assessing agreement among crime scene measurement methods.
Maria Lawas1,2, Susan Y Williams2,3, Steven Jameson2,3
1Visiting Scientist Program, Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA.
Journal of Forensic Sciences
|March 24, 2022
Summary
Crime scene documentation accuracy varies by method. FARO LiDAR showed high agreement with Total Station, while drones without ground control points (GCPs) had the least accuracy. GCPs are crucial for drone measurements.
Area of Science:
- Forensic Science
- Geomatics Engineering
- Photogrammetry
Background:
- Accurate crime scene reconstruction is vital for legal proceedings.
- Numerous documentation methods exist, but their comparative accuracy is not well-established.
- Understanding measurement accuracy across different distances is crucial for method selection.
Purpose of the Study:
- To evaluate and compare the accuracy of eight crime scene documentation methods.
- To assess the impact of measurement distance on the accuracy of these methods.
- To determine the influence of ground control points (GCPs) on drone-based measurements.
Main Methods:
- Relative accuracy assessment of eight documentation methods against a Total Station (ground truth).
- Measurements were taken between reference ground targets in an outdoor scene.
- Analysis included the effect of measurement distance and the use of GCPs or reference scales.
Main Results:
- Most methods showed small differences (< 0.25 inches) compared to Total Station.
- FARO LiDAR demonstrated the highest agreement; drones without GCPs showed the least.
- GCPs or reference scales were essential for mitigating distance-related imprecision in drone and orthomosaic methods.
- No significant difference was found between 2D and 3D measurement configurations for Total Station.
Conclusions:
- Method selection for crime scene documentation should consider accuracy and the need for ground control points.
- Establishing a known distance range (ground truth) is essential for validating new measurement tools.
- FARO LiDAR and Total Station offer reliable measurements, while drone accuracy is significantly enhanced by GCPs.
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