Scale bar
Definition
A physical ruler or L-shaped measuring device placed in the field of view before a photograph is taken. It provides a known dimension in the image and is required for all forensic archaeological photographs.
- Required in forensic archaeological photographs
- All forensic archaeological photographs must include a scale bar
- Used in
- Site photography, clinical injury documentation, colposcopy imaging
Common questions
Why do forensic photographs need a scale bar?+
A scale bar shows a known measurement in the photo so viewers can judge the true size of evidence or injuries. Without it, you cannot tell if something in the image is large or small, which weakens its value in court.
What makes a good scale bar for forensic photos?+
A physical ruler or L-shaped measuring device placed in the field of view before the photo is taken works best. It must be visible in the frame and have a clear, known dimension so the size of evidence can be determined from the image alone.
Where should the scale bar be positioned in the photo?+
In site photography, the scale bar is placed in the field of view before shooting. In clinical photos of injuries, it is placed adjacent to the finding so both are visible in the same image.
Related terms
- Photographic log
- A written record, kept on site alongside the context records, that logs each photograph with its file name, date, time, photographer, subject...
- Colour checker
- A calibrated chart of known colour patches (typically the Macbeth ColorChecker or equivalent) photographed in the same light as the scene, used...
- Colposcope
- A binocular optical device with bright coaxial illumination and variable magnification (typically 4x-40x), originally designed for cervical examination but widely adopted in...
- Context plan
- A hand-drawn plan at a standard scale (typically 1:10 or 1:20) showing the outline and internal features of one context. Drawn before...
- EXIF metadata
- Exchangeable Image File Format data embedded in a digital image by the camera. Includes date, time, camera model, exposure settings, and GPS...
- Forensic photography
- Photography conducted to evidentiary standards, producing images that can be authenticated as accurate representations of a finding at a specific time, with...
- RAW format
- A camera capture format that records unprocessed sensor data, preserving all original exposure and colour information. RAW files are preferred over JPEG...
- Section drawing
- A vertical cut through the excavated sequence, drawn at 1:10 or 1:20, showing the relative positions, depths, and angles of all contexts...
- Toluidine blue
- A nuclear dye applied to anogenital skin that is taken up by nucleated cells exposed by micro-lacerations. It stains micro-tears dark blue,...
Explained in these topics
- Site Photography and IllustrationA physical ruler or L-shaped measuring device placed in the field of view before a photograph is taken. It provides a known dimension in the image and is requi...
- Forensic Photography and Colposcopy in Clinical SettingsA reference object of known length placed adjacent to an injury in a photograph. Without a scale bar, the size of a finding cannot be determined from the image...