Description
Divide by ruler scale, then multiply by suppliedPlaneFactor.
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.
Divide by ruler scale, then multiply by suppliedPlaneFactor.
When to use this tool
Use Image Ruler Scale Parallax Term when you need an explicit image or physical-measurement term.
How to use the tool and how it works
- Enter pixelLength, rulerPixelsPerUnit, suppliedPlaneFactor. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read nominalLength, planeCorrectedLength. Use the output convention below.
Require nonnegative pixelLength and positive rulerPixelsPerUnit and plane factor. Divide by ruler scale, then multiply by suppliedPlaneFactor.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| pixelLength | Pixel Length | Required. Finite number; minimum 0. |
| rulerPixelsPerUnit | Ruler Pixels Per Unit | Required. Finite number; strictly above 0. |
| suppliedPlaneFactor | Supplied Plane Factor | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| nominalLength | Nominal Length | Required. Finite number. |
| planeCorrectedLength | Plane Corrected Length | Required. Finite number. |
{
"input": {
"pixelLength": 120,
"rulerPixelsPerUnit": 20,
"suppliedPlaneFactor": 0.9
},
"output": {
"nominalLength": 6,
"planeCorrectedLength": 5.4
}
}Limitations and assumptions
- The factor is not derived from geometry. Perspective correction assumptions, image integrity, and forensic source identification are not verified.
- 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
- Evidence Scale Perspective Length Factor
Return ruler-scaled length, then multiply it by objectDepth/rulerDepth.
- Photographed Footwear Scale Length Term
Return reference length per pixel and scaled impression length divided by enlargement.