A comparative study of photogrammetric methods using panoramic photography in a forensic context

Area of Science:

• Forensic Science
• Measurement Science

Background:

• Accurate crime scene measurement is crucial for documentation.
• Global standards for measurement accuracy vary, with no UK standard and a US standard of 0.25 inch.
• International Organisation for Standardisation (ISO) 17020 accreditation requires competency testing and calibrated measuring devices with defined accuracy limits.

Purpose of the Study:

• To compare the measurement accuracy and precision of tape measures versus 360° camera photogrammetry software.
• To evaluate the reproducibility and practical application of each measurement method in a crime scene context.

Main Methods:

• Participants measured ten fixed and non-fixed items using both a tape measure and a 360° camera with photogrammetry software.
• Control measurements were taken using a laser distance measure.
• Statistical analysis, including a Wilcoxon Signed Rank test, was used to compare the methods.

Main Results:

• Statistically significant differences were found between tape, software, and control measurements, though most differences were negligible (millimetres).
• Tape measures demonstrated higher accuracy, while the photogrammetry software offered greater precision and reproducibility.
• Measurement errors were linked to human error with the software and transcription errors with the tape measure.

Conclusions:

• The tape measure was more accurate, but the photogrammetry software provided superior reproducibility and flexibility for crime scene documentation.
• Training is recommended for users of photogrammetry software to mitigate human error.
• Despite minor differences, both methods have implications for forensic measurement standards and practices.