Description
Return reference length per pixel and scaled impression length divided by enlargement.
Forensic measurement calculations require a known calibration, geometric model and uncertainty convention. A converted length, ratio or residual describes the supplied measurements; it does not establish common origin, identity or evidentiary strength.
Return reference length per pixel and scaled impression length divided by enlargement.
When to use this tool
Use Photographed Footwear Scale Length Term when you need an explicit image or physical-measurement term.
How to use the tool and how it works
- Enter impressionPixels, referencePixels, referenceLength, enlargementFactor. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read imageScale, originalLength. Use the output convention below.
Require nonnegative impression pixels and positive reference pixels, reference length and enlargement factor. Return reference length per pixel and scaled impression length divided by enlargement.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| impressionPixels | Impression Pixels | Required. Finite number; minimum 0. |
| referencePixels | Reference Pixels | Required. Finite number; strictly above 0. |
| referenceLength | Reference Length | Required. Finite number; strictly above 0. |
| enlargementFactor | Enlargement Factor | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| imageScale | Image Scale | Required. Finite number. |
| originalLength | Original Length | Required. Finite number. |
{
"input": {
"impressionPixels": 600,
"referencePixels": 200,
"referenceLength": 100,
"enlargementFactor": 1
},
"output": {
"imageScale": 0.5,
"originalLength": 300
}
}Limitations and assumptions
- Enlargement is a supplied linear factor, not an area factor. Perspective, plane alignment, source attribution and footwear identification are not assessed.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the validated measurement method and original evidence for interpretation. Include calibration, geometry, uncertainty and the full evidentiary context rather than turning a numerical match into an identification.
References
Similar or alternative tools
- Measurement Scale Photo Ratio
Convert the pixel length and divide by secondLength for ratio.
- Evidence Scale Perspective Length Factor
Return ruler-scaled length, then multiply it by objectDepth/rulerDepth.