Four-Tier Protocol
Definition
The standard crime-scene photography sequence: overall (establishing), mid-range (relationship), close-up with scale, and close-up without scale. Each tier answers a distinct spatial question.
- Sequence
- Overall, mid-range, close-up with scale, close-up without scale
- Purpose
- Documents spatial relationships at increasing detail
- Field
- Crime-scene photography
- Scale use
- One close-up always taken without a scale first
Common questions
Why is a close-up taken both with and without a scale rather than just with one?+
The scale-free image proves the item and its immediate surroundings were not disturbed or altered by placing the scale, establishing an unaltered record, while the scaled image afterward allows accurate measurement of the item's true size.
What spatial question does the mid-range photograph answer that the overall shot cannot?+
The overall shot establishes the general scene layout, but it cannot show precisely how a specific item relates to fixed reference points nearby. The mid-range shot bridges that gap, showing the item in relation to nearby landmarks like furniture or doorways.
What happens if an item is moved or the scene disturbed before all four tiers are captured?+
Any gap in the sequence, especially skipping the overall or mid-range stage, breaks the documented spatial chain connecting the item to the wider scene, weakening the photographic record's ability to withstand challenge in court.
Related terms
- ABFO No. 2 Scale
- The right-angle L-shaped reference scale with circular targets used in bite mark photography. Its design enables post-capture correction of lens distortion and...
- ENFSI
- European Network of Forensic Science Institutes: the voluntary network of national forensic institutes across Europe and neighbouring regions, focused on method harmonisation,...
- Equirectangular Projection
- A panoramic map projection that preserves angular relationships in all directions; preferred for 360-degree room documentation and virtual reality scene reconstruction.
- EXIF Metadata
- Exchangeable Image File Format data embedded in a digital image by the camera. Includes date, time, camera model, exposure settings, and GPS...
- IAI
- International Association for Identification; includes the Crime Scene Certification programme requiring demonstrated forensic photography competency.
- Light Painting
- A technique where a handheld light source is moved across a scene during a long camera exposure to evenly illuminate large areas;...
- Nodal Point
- The optical centre of a lens from which perspective relationships are computed. Panoramas must rotate around the nodal point to avoid parallax-induced...
- Parallel-Plane Requirement
- The requirement that the camera sensor plane be parallel to the evidence-and-scale plane to eliminate keystoning distortion and allow accurate metric measurement...
- Photo Log
- The contemporaneous record tying each forensic image to its capture time, location, equipment, exposure settings, and subject description. The primary chain-of-custody document...
- SWGIT
- Scientific Working Group for Imaging Technologies (US); publishes multi-section guidelines on crime-scene photography, digital imaging, and specialised photographic techniques for law enforcement.