ISO 8721:2018

Overview

ISO 8721:2018 - "Road vehicles - Measurement techniques in impact tests - Optical instrumentation" specifies performance criteria for optical data channels used in vehicle impact testing. The standard covers how numerical time and space data are obtained from images, and defines minimum quality criteria (performance and accuracy) to help different laboratories compare and reproduce impact-test results. Annexes A–D provide methods for measuring indices and quality parameters using a calibration target, reference distances and analysis systems.

Keywords: ISO 8721:2018, optical instrumentation, impact tests, optical data channel, road vehicles, calibration target, frame rate, synchronization.

Key Topics and Technical Requirements

• Optical data channel definition: one or more image recording devices plus analysis system (image capture, image analysis, and data correction).
• Performance and accuracy: the standard defines a performance value (overall suitability) and accuracy value (relative and absolute measurement error) for the optical data channel.
• Indices and checks: a set of indices assess subprocesses and conditions, such as:
  • Motion blur index (imb) and point motion index (ipm)
  • Target size (its) and target detection index (itd)
  • Focal length index (ifl) and distortion index (id)
  • Control point distribution (icpd) and camera set‑up (ics)
  • Time base (itb), time origin identification (itoi) and synchronism (isy)
  • Scale and plane‑scale indices for 2D analysis; intersection index for 3D
• 2D vs 3D performance: separate evaluation methodologies and performance values for 2D film analysis and 3D film analysis.
• Measurement procedures: defines online and offline procedure types, methods to determine length measurement error (ΔL), reference-distance accuracy, and conformity statements.
• Documentation: requirements for reporting indices, derived quantities and user-defined variables to support reproducibility.

Practical Applications and Users

ISO 8721:2018 is used to ensure reliable optical measurement in:

• Vehicle crash and impact testing facilities
• Automotive safety labs performing high-speed imaging
• Manufacturers and OEMs validating occupant protection and component performance
• Test-equipment vendors (cameras, synchronisation, analysis software)
• Accreditation bodies and inter-laboratory comparison programs

Benefits:

• Improves comparability of kinematic and displacement data derived from images
• Guides camera set-up, calibration target use and time-synchronization practice
• Supports traceable reporting of measurement uncertainty and conformity

Related Standards

• ISO 6487 - Road vehicles - Measurement techniques in impact tests - Instrumentation (normative reference cited by ISO 8721:2018)
• Prepared by ISO/TC 22 (Road vehicles), Subcommittee SC 36 (Safety and impact testing)

For labs and engineers working with high‑speed optical systems in crash testing, ISO 8721:2018 provides a structured, index-based framework to assess and document optical measurement quality, facilitating consistent and comparable impact-test results.