3D Impression
Definition
An impression made in a deformable medium: soil, sand, snow, mud, soft asphalt. The sole or tread pushes into the medium and leaves a depth-bearing copy.
- Media
- Soil, sand, snow, mud, soft asphalt
- Mechanism
- Sole or tread pushes in, leaves a depth-bearing copy
- Contrast
- Depth present, unlike a 2D impression
Common questions
What information can a 3D footwear impression provide that a 2D one cannot?+
It preserves depth and profile detail, including three-dimensional tread wear features, that a flat residue print on a hard surface simply cannot record because it has no depth to capture.
Why does the condition of the medium, such as wet versus dry sand, matter for this evidence?+
The medium's consistency affects how sharply tread detail is retained and how well a plaster or dental stone cast will pick up fine features, so examiners note and sometimes stabilise the medium before casting.
Related terms
- 2D Impression
- A two-dimensional print on a hard, flat surface (tiled floor, polished cement, paper). Lifted with electrostatic dust lifter (ESLA), gel lifter, or...
- Class Characteristic
- A feature shared by an entire group of objects (every shoe of one model has the same sole tread; every tire of...
- Individual Characteristic
- A characteristic unique to a specific typewriter unit arising from manufacturing variation or service wear; used to identify or eliminate a specific...
- Dental Stone
- A gypsum-based casting material harder and finer than plaster of Paris. Preferred for forensic 3-D casts because it captures detail at the...
- Drag Factor (μ)
- The effective coefficient of friction between the tyre and the road surface during a braking event. Used in the skid-mark speed formula....
- Gait Pattern
- The geometric and rhythmic signature of a person's walk. Captured as stride length, step length, cadence, foot angle and walking line. Used...
- Latent Impression
- An impression that is invisible or barely visible until developed or lifted. Dust impressions on dark floors and oblique-light-only impressions sit here.
- Patent Impression
- An impression that is visible to the naked eye without enhancement. A bloody shoeprint on white tile is patent.
- TWI
- Treadwear indicator. A small raised ridge moulded across the tread groove of every tire at 1.6 mm depth. When the surrounding tread...
Explained in these topics
- Footwear, Tyre and Footprint Impression Evidence
- Track Marks: Foot, Shoe, Tire, Skid Marks and Gait PatternA three-dimensional impression in a soft medium (mud, sand, soil, snow). Photographed in situ with scale and oblique light, then cast with dental stone.