Description
Convert the pixel length and divide by secondLength for ratio.
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.
Convert the pixel length and divide by secondLength for ratio.
When to use this tool
Use Measurement Scale Photo Ratio when you need an explicit image or physical-measurement term.
How to use the tool and how it works
- Enter photoPixels, scalePixels, suppliedScaleLength, secondLength. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read measuredLength, ratio. Use the output convention below.
Require nonnegative photoPixels and positive scalePixels, suppliedScaleLength and secondLength. Convert the pixel length and divide by secondLength for ratio.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| photoPixels | Photo Pixels | Required. Finite number; minimum 0. |
| scalePixels | Scale Pixels | Required. Finite number; strictly above 0. |
| suppliedScaleLength | Supplied Scale Length | Required. Finite number; strictly above 0. |
| secondLength | Second Length | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| measuredLength | Measured Length | Required. Finite number. |
| ratio | Dimensionless ratio under the numerator/denominator convention above. | Required. Finite number. |
{
"input": {
"photoPixels": 40,
"scalePixels": 20,
"suppliedScaleLength": 5,
"secondLength": 8
},
"output": {
"measuredLength": 10,
"ratio": 1.25
}
}Limitations and assumptions
- Both physical lengths share units; calibration and perspective are assumed. A matching ratio does not establish common origin or identity.
- 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
- Photographed Footwear Scale Length Term
Return reference length per pixel and scaled impression length divided by enlargement.
- Image Ruler Scale Parallax Term
Divide by ruler scale, then multiply by suppliedPlaneFactor.